Posts Tagged ‘configure’

How to configure multiple haproxies and frontends to log in separate log files via rsyslog

Monday, September 5th, 2022

log-multiple-haproxy-servers-to-separate-files-log-haproxy-froentend-to-separate-file-haproxy-rsyslog-Logging-diagram
In my last article How to create multiple haproxy instance separate processes for different configuration listeners,  I've shortly explained how to create a multiple instances of haproxies by cloning the systemd default haproxy.service and the haproxy.cfg to haproxyX.cfg.
But what if you need also to configure a separate logging for both haproxy.service and haproxy-customname.service instances how this can be achieved?

The simplest way is to use some system local handler staring from local0 to local6, As local 1,2,3 are usually used by system services a good local handler to start off would be at least 4.
Lets say we already have the 2 running haproxies, e.g.:

[root@haproxy2:/usr/lib/systemd/system ]# ps -ef|grep -i hapro|grep -v grep
root      128464       1  0 Aug11 ?        00:01:19 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -S /run/haproxy-master.sock
haproxy   128466  128464  0 Aug11 ?        00:49:29 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -S /run/haproxy-master.sock

root      346637       1  0 13:15 ?        00:00:00 /usr/sbin/haproxy-customname-wrapper -Ws -f /etc/haproxy/haproxy_customname_prod.cfg -p /run/haproxy_customname_prod.pid -S /run/haproxy-customname-master.sock
haproxy   346639  346637  0 13:15 ?        00:00:00 /usr/sbin/haproxy-customname-wrapper -Ws -f /etc/haproxy/haproxy_customname_prod.cfg -p /run/haproxy_customname_prod.pid -S /run/haproxy-customname-master.sock


1. Configure local messaging handlers to work via /dev/log inside both haproxy instance config files
 

To congigure the separte logging we need to have in /etc/haproxy/haproxy.cfg and in /etc/haproxy/haproxy_customname_prod.cfg the respective handlers.

To log in separate files you should already configured in /etc/haproxy/haproxy.cfg something like:

 

global
        stats socket /var/run/haproxy/haproxy.sock mode 0600 level admin #Creates Unix-Like socket to fetch stats
        log /dev/log    local0
        log /dev/log    local1 notice

#       nbproc 1
#       nbthread 2
#       cpu-map auto:1/1-2 0-1
        nbproc          1
        nbthread 2
        cpu-map         1 0
        cpu-map         2 1
        chroot /var/lib/haproxy
        user haproxy
        group haproxy
        daemon
        maxconn 99999

defaults
        log     global
        mode    tcp


        timeout connect 5000
        timeout connect 30s
        timeout server 10s

    timeout queue 5s
    timeout tunnel 2m
    timeout client-fin 1s
    timeout server-fin 1s

    option forwardfor
        maxconn 3000
    retries                 15

frontend http-in
        mode tcp

        option tcplog
        log global

 

        option logasap
        option forwardfor
        bind 0.0.0.0:80

default_backend webservers_http
backend webservers_http
    fullconn 20000
        balance source
stick match src
    stick-table type ip size 200k expire 30m

        server server-1 192.168.1.50:80 check send-proxy weight 255 backup
        server server-2 192.168.1.54:80 check send-proxy weight 254
        server server-3 192.168.0.219:80 check send-proxy weight 252 backup
        server server-4 192.168.0.210:80 check send-proxy weight 253 backup
        server server-5 192.168.0.5:80 maxconn 3000 check send-proxy weight 251 backup

For the second /etc/haproxy/haproxy_customname_prod.cfg the logging configuration should be similar to:
 

global
        stats socket /var/run/haproxy/haproxycustname.sock mode 0600 level admin #Creates Unix-Like socket to fetch stats
        log /dev/log    local5
        log /dev/log    local5 notice

#       nbproc 1
#       nbthread 2
#       cpu-map auto:1/1-2 0-1
        nbproc          1
        nbthread 2
        cpu-map         1 0
        cpu-map         2 1
        chroot /var/lib/haproxy
        user haproxy
        group haproxy
        daemon
        maxconn 99999

defaults
        log     global
        mode    tcp

 

2. Configure separate haproxy Frontend logging via local5 inside haproxy.cfg
 

As a minimum you need a configuration for frontend like:

 

frontend http-in
        mode tcp

        option tcplog
        log /dev/log    local5 debug
…..
….

..
.

Of course the mode tcp in my case is conditional you might be using mode http etc. 


3. Optionally but (preferrably) make local5 / local6 handlers to work via rsyslogs UDP imudp protocol

 

In this example /dev/log is straightly read by haproxy instead of sending the messages first to rsyslog, this is a good thing in case if you have doubts that rsyslog might stop working and respectively you might end up with no logging, however if you prefer to use instead rsyslog which most of people usually do you will have instead for /etc/haproxy/haproxy.cfg to use config:

global
    log          127.0.0.1 local6 debug

defaults
        log     global
        mode    tcp

And for /etc/haproxy_customname_prod.cfg config like:

global
    log          127.0.0.1 local5 debug

defaults
        log     global
        mode    tcp

If you're about to send the haproxy logs directly via rsyslog, it should have enabled in /etc/rsyslog.conf the imudp module if you're not going to use directly /dev/log

# provides UDP syslog reception
module(load="imudp")
input(type="imudp" port="514")

 

4. Prepare first and second log file and custom frontend output file and set right permissions
 

Assumably you already have /var/log/haproxy.log and this will be the initial haproxy log if you don't want to change it, normally it is installed on haproxy package install time on Linux and should have some permissions like following:

root@haproxy2:/etc/rsyslog.d# ls -al /var/log/haproxy.log
-rw-r–r– 1 haproxy haproxy 6681522  1 сеп 16:05 /var/log/haproxy.log


To create the second config with exact permissions like haproxy.log run:

root@haproxy2:/etc/rsyslog.d# touch /var/log/haproxy_customname.log
root@haproxy2:/etc/rsyslog.d# chown haproxy:haproxy /var/log/haproxy_customname.log

Create the haproxy_custom_frontend.log file that will only log output of exact frontend or match string from the logs
 

root@haproxy2:/etc/rsyslog.d# touch  /var/log/haproxy_custom_frontend.log
root@haproxy2:/etc/rsyslog.d# chown haproxy:haproxy  /var/log/haproxy_custom_frontend.log


5. Create the rsyslog config for haproxy.service to log via local6 to /var/log/haproxy.log
 

root@haproxy2:/etc/rsyslog.d# cat 49-haproxy.conf
# Create an additional socket in haproxy's chroot in order to allow logging via
# /dev/log to chroot'ed HAProxy processes
$AddUnixListenSocket /var/lib/haproxy/dev/log

# Send HAProxy messages to a dedicated logfile
:programname, startswith, "haproxy" {
  /var/log/haproxy.log
  stop
}

 

Above configs will make anything returned with string haproxy (e.g. proccess /usr/sbin/haproxy) to /dev/log to be written inside /var/log/haproxy.log and trigger a stop (by the way the the stop command works exactly as the tilda '~' discard one, except in some newer versions of haproxy the ~ is no now obsolete and you need to use stop instead (bear in mind that ~ even though obsolete proved to be working for me whether stop not ! but come on this is no strange this is linux mess), for example if you run latest debian Linux 11 as of September 2022 haproxy with package 2.2.9-2+deb11u3.
 

6. Create configuration for rsyslog to log from single Frontend outputting local2 to /var/log/haproxy_customname.log
 

root@haproxy2:/etc/rsyslog.d# cat 48-haproxy.conf
# Create an additional socket in haproxy's chroot in order to allow logging via
# /dev/log to chroot'ed HAProxy processes
$AddUnixListenSocket /var/lib/haproxy/dev/log

# Send HAProxy messages to a dedicated logfile
#:programname, startswith, "haproxy" {
#  /var/log/haproxy.log
#  stop
#}
# GGE/DPA 2022/08/02: HAProxy logs to local2, save the messages
local5.*                                                /var/log/haproxy_customname.log
 


You might also explicitly define the binary that will providing the logs inside the 48-haproxy.conf as we have a separate /usr/sbin/haproxy-customname-wrapper in that way you can log the output from the haproxy instance only based
on its binary command and you can omit writting to local5 to log via it something else 🙂

root@haproxy2:/etc/rsyslog.d# cat 48-haproxy.conf
# Create an additional socket in haproxy's chroot in order to allow logging via
# /dev/log to chroot'ed HAProxy processes
$AddUnixListenSocket /var/lib/haproxy/dev/log

# Send HAProxy messages to a dedicated logfile
#:programname, startswith, "haproxy" {
#  /var/log/haproxy.log
#  stop
#}
# GGE/DPA 2022/08/02: HAProxy logs to local2, save the messages

:programname, startswith, "haproxy-customname-wrapper " {
 
/var/log/haproxy_customname.log
  stop
}

 

7. Create the log file to log the custom frontend of your preference e.g. /var/log/haproxy_custom_frontend.log under local5 /prepare rsyslog config for
 

root@haproxy2:/etc/rsyslog.d# cat 47-haproxy-custom-frontend.conf
$ModLoad imudp
$UDPServerAddress 127.0.0.1
$UDPServerRun 514
#2022/02/02: HAProxy logs to local6, save the messages
local4.*                                                /var/log/haproxy_custom_frontend.log
:msg, contains, "https-in" ~

The 'https-in' is my frontend inside /etc/haproxy/haproxy.cfg it returns the name of it every time in /var/log/haproxy.log therefore I will log the frontend to local5 and to prevent double logging inside /var/log/haproxy.log of connections incoming towards the same frontend inside /var/log/haproxy.log, I have the tilda symbol '~' which instructs rsyslog to discard any message coming to rsyslog with "https-in" string in, immediately after the same frontend as configured inside /etc/haproxy/haproxy.cfg will output the frontend operations inside local5.


!!! Note that for rsyslog it is very important to have the right order of configurations, the configuration order is being considered based on the file numbering. !!!
 

Hence notice that my filter file number 47_* preceeds the other 2 configured rsyslog configs.
 

root@haproxy2:/etc/rsyslog.d# ls -1
47-haproxy-custom-frontend.conf
48-haproxy.conf
49-haproxy.conf

This will make 47-haproxy-custom-frontend.conf to be read and processed first 48-haproxy.conf processed second and 49-haproxy.conf processed third.


8. Reload rsyslog and haproxy and test

 

root@haproxy2: ~# systemctl restart rsyslog
root@haproxy2: ~# systemctl restart haproxy
root@haproxy2: ~# systemctl status rsyslog

● rsyslog.service – System Logging Service
     Loaded: loaded (/lib/systemd/system/rsyslog.service; enabled; vendor preset: enabled)
     Active: active (running) since Thu 2022-09-01 17:34:51 EEST; 1s ago
TriggeredBy: ● syslog.socket
       Docs: man:rsyslogd(8)
             man:rsyslog.conf(5)
             https://www.rsyslog.com/doc/
   Main PID: 372726 (rsyslogd)
      Tasks: 6 (limit: 4654)
     Memory: 980.0K
        CPU: 8ms
     CGroup: /system.slice/rsyslog.service
             └─372726 /usr/sbin/rsyslogd -n -iNONE

сеп 01 17:34:51 haproxy2 systemd[1]: Stopped System Logging Service.
сеп 01 17:34:51 haproxy2 rsyslogd[372726]: warning: ~ action is deprecated, consider using the 'stop' statement instead [v8.210>
сеп 01 17:34:51 haproxy2 systemd[1]: Starting System Logging Service…
сеп 01 17:34:51 haproxy2 rsyslogd[372726]: [198B blob data]
сеп 01 17:34:51 haproxy2 systemd[1]: Started System Logging Service.
сеп 01 17:34:51 haproxy2 rsyslogd[372726]: [198B blob data]
сеп 01 17:34:51 haproxy2 rsyslogd[372726]: [198B blob data]
сеп 01 17:34:51 haproxy2 rsyslogd[372726]: [198B blob data]
сеп 01 17:34:51 haproxy2 rsyslogd[372726]: imuxsock: Acquired UNIX socket '/run/systemd/journal/syslog' (fd 3) from systemd.  [>
сеп 01 17:34:51 haproxy2 rsyslogd[372726]: [origin software="rsyslogd" swVersion="8.2102.0" x-pid="372726" x-info="https://www.

Do some testing with some tool like curl / wget / lynx / elinks etc. on each of the configured haproxy listeners and frontends and check whether everything ends up in the correct log files.
That's all folks enjoy ! 🙂
 

How to test RAM Memory for errors in Linux / UNIX OS servers. Find broken memory RAM banks

Friday, December 3rd, 2021

test-ram-memory-for-errors-linux-unix-find-broken-memory-logo

 

1. Testing the memory with motherboard integrated tools
 

Memory testing has been integral part of Computers for the last 50 years. In the dawn of computers those older perhaps remember memory testing was part of the computer initialization boot. And this memory testing was delaying the boot with some seconds and the user could see the memory numbers being counted up to the amount of memory. With the increased memory modern computers started to have and the annoyance to wait for a memory check program to check the computer hardware memory on modern computers this check has been mitigated or completely removed on some hardware.
Thus under some circumstances sysadmins or advanced computer users might need to check the memory, especially if there is some suspicion for memory damages or if for example a home PC starts crashing with Blue screens of Death on Windows without reason or simply the PC or some old arcane Linux / UNIX servers gets restarted every now and then for now apparent reason. When such circumstances occur it is an idea to start debugging the hardware issue with a simple memory check.

There are multiple ways to test installed memory banks on a server laptop or local home PC both integrated and using external programs.
On servers that is usually easily done from ILO or IPMI or IDRAC access (usually web) interface of the vendor, on laptops and home usage from BIOS or UEFI (Unified Extensible Firmware Interface) acces interface on system boot that is possible as well.

memtest-hp
HP BIOS Setup

An old but gold TIP, more younger people might not know is the

 

Prolonged SHIFT key press which once held with the user instructs the machine to initiate a memory test before the computer starts reading what is written in the boot loader.

So before anything else from below article it might be a good idea to just try HOLD SHIFT for 15-20 seconds after a complete Shut and ON from the POWER button.

If this test does not triggered or it is triggered and you end up with some corrupted memory but you're not sure which exact Memory bank is really crashing and want to know more on what memory Bank and segments are breaking up you might want to do a more thorough testing. In below article I'll try to explain shortly how this can be done.


2. Test the memory using a boot USB Flash Drive / DVD / CD 
 

Say hello to memtest86+. It is a Linux GRUB boot loader bootable utility that tests physical memory by writing various patterns to it and reading them back. Since memtest86+ runs directly off the hardware it does not require any operating system support for execution. Perhaps it is important to mention that memtest86 (is PassMark memtest86)and memtest86+ (An Advanced Memory diagnostic tool) are different tools, the first is freeware and second one is FOSS software.

To use it all you'll need is some version of Linux. If you don't already have some burned in somewhere at your closet, you might want to burn one.
For Linux / Mac users this is as downloading a Linux distribution ISO file and burning it with

# dd if=/path/to/iso of=/dev/sdbX bs=80M status=progress


Windows users can burn a Live USB with whatever Linux distro or download and burn the latest versionof memtest86+ from https://www.memtest.org/  on Windows Desktop with some proggie like lets say UnetBootIn.
 

2.1. Run memtest86+ on Ubuntu

Many Linux distributions such as Ubuntu 20.0 comes together with memtest86+, which can be easily invoked from GRUB / GRUB2 Kernel boot loader.
Ubuntu has a separate menu pointer for a Memtest.

ubuntu-grub-2-04-boot-loader-memtest86-menu-screenshot

Other distributions RPM based distributions such as CentOS, Fedora Linux, Redhat things differ.

2.2. memtest86+ on Fedora


Fedora used to have the memtest86+ menu at the GRUB boot selection prompt, but for some reason removed it and in newest Fedora releases as of time such as Fedora 35 memtest86+ is preinstalled and available but not visible, to start on  already and to start a memtest memory test tool:

  •   Boot a Fedora installation or Rescue CD / USB. At the prompt, type "memtest86".

boot: memtest86

2.3 memtest86+ on RHEL Linux

The memtest86+tool is available as an RPM package from Red Hat Network (RHN) as well as a boot option from the Red Hat Enterprise Linux rescue disk.
And nowadays Red Hat Enterprise Linux ships by default with the tool.

Prior redhat (now legacy) releases such as on RHEL 5.0 it has to be installed and configure it with below 3 commands.

[root@rhel ~]# yum install memtest86+
[root@rhel ~]# memtest-setup
[root@rhel ~]# grub2-mkconfig -o /boot/grub2/grub.cfg


    Again as with CentOS to boot memtest86+ from the rescue disk, you will need to boot your system from CD 1 of the Red Hat Enterprise Linux installation media, and type the following at the boot prompt (before the Linux kernel is started):

boot: memtest86

memtestx86-8gigabytes-of-memory-boot-screenshot
memtest86+ testing 5 memory slots

As you see all on above screenshot the Memory banks are listed as Slots. There are a number of Tests to be completed until
it can be said for sure memory does not have any faulty cells. 
The

Pass: 0
Errors: 0 

Indicates no errors, so in the end if memtest86 does not find anything this values should stay at zero.
memtest86+ is also usable to detecting issues with temperature of CPU. Just recently I've tested a PC thinking that some memory has defects but it turned out the issue on the Computer was at the CPU's temperature which was topping up at 80 – 82 Celsius.

If you're unfortunate and happen to get some corrupted memory segments you will get some red fields with the memory addresses found to have corrupted on Read / Write test operations:

memtest86-returning-memory-address-errors-screenshot


2.4. Install and use memtest and memtest86+ on Debian / Mint Linux

You can install either memtest86+ or just for the fun put both of them and play around with both of them as they have a .deb package provided out of debian non-free /etc/apt/sources.list repositories.


root@jeremiah:/home/hipo# apt-cache show memtest86 memtest86+
Package: memtest86
Version: 4.3.7-3
Installed-Size: 302
Maintainer: Yann Dirson <dirson@debian.org>
Architecture: amd64
Depends: debconf (>= 0.5) | debconf-2.0
Recommends: memtest86+
Suggests: hwtools, memtester, kernel-patch-badram, grub2 (>= 1.96+20090523-1) | grub (>= 0.95+cvs20040624), mtools
Description-en: thorough real-mode memory tester
 Memtest86 scans your RAM for errors.
 .
 This tester runs independently of any OS – it is run at computer
 boot-up, so that it can test *all* of your memory.  You may want to
 look at `memtester', which allows testing your memory within Linux,
 but this one won't be able to test your whole RAM.
 .
 It can output a list of bad RAM regions usable by the BadRAM kernel
 patch, so that you can still use you old RAM with one or two bad bits.
 .
 This is the last DFSG-compliant version of this software, upstream
 has opted for a proprietary development model starting with 5.0.  You
 may want to consider using memtest86+, which has been forked from an
 earlier version of memtest86, and provides a different set of
 features.  It is available in the memtest86+ package.
 .
 A convenience script is also provided to make a grub-legacy-based
 floppy or image.

Description-md5: 0ad381a54d59a7d7f012972f613d7759
Homepage: http://www.memtest86.com/
Section: misc
Priority: optional
Filename: pool/main/m/memtest86/memtest86_4.3.7-3_amd64.deb
Size: 45470
MD5sum: 8dd2a4c52910498d711fbf6b5753bca9
SHA256: 09178eca21f8fd562806ccaa759d0261a2d3bb23190aaebc8cd99071d431aeb6

Package: memtest86+
Version: 5.01-3
Installed-Size: 2391
Maintainer: Yann Dirson <dirson@debian.org>
Architecture: amd64
Depends: debconf (>= 0.5) | debconf-2.0
Suggests: hwtools, memtester, kernel-patch-badram, memtest86, grub-pc | grub-legacy, mtools
Description-en: thorough real-mode memory tester
 Memtest86+ scans your RAM for errors.
 .
 This tester runs independently of any OS – it is run at computer
 boot-up, so that it can test *all* of your memory.  You may want to
 look at `memtester', which allows to test your memory within Linux,
 but this one won't be able to test your whole RAM.
 .
 It can output a list of bad RAM regions usable by the BadRAM kernel
 patch, so that you can still use your old RAM with one or two bad bits.
 .
 Memtest86+ is based on memtest86 3.0, and adds support for recent
 hardware, as well as a number of general-purpose improvements,
 including many patches to memtest86 available from various sources.
 .
 Both memtest86 and memtest86+ are being worked on in parallel.
Description-md5: aa685f84801773ef97fdaba8eb26436a
Homepage: http://www.memtest.org/

Tag: admin::benchmarking, admin::boot, hardware::storage:floppy,
 interface::text-mode, role::program, scope::utility, use::checking
Section: misc
Priority: optional
Filename: pool/main/m/memtest86+/memtest86+_5.01-3_amd64.deb
Size: 75142
MD5sum: 4f06523532ddfca0222ba6c55a80c433
SHA256: ad42816e0b17e882713cc6f699b988e73e580e38876cebe975891f5904828005
 

 

root@jeremiah:/home/hipo# apt-get install –yes memtest86+

root@jeremiah:/home/hipo# apt-get install –yes memtest86

Reading package lists… Done
Building dependency tree       
Reading state information… Done
Suggested packages:
  hwtools kernel-patch-badram grub2 | grub
The following NEW packages will be installed:
  memtest86
0 upgraded, 1 newly installed, 0 to remove and 21 not upgraded.
Need to get 45.5 kB of archives.
After this operation, 309 kB of additional disk space will be used.
Get:1 http://ftp.de.debian.org/debian buster/main amd64 memtest86 amd64 4.3.7-3 [45.5 kB]
Fetched 45.5 kB in 0s (181 kB/s)     
Preconfiguring packages …
Selecting previously unselected package memtest86.
(Reading database … 519985 files and directories currently installed.)
Preparing to unpack …/memtest86_4.3.7-3_amd64.deb …
Unpacking memtest86 (4.3.7-3) …
Setting up memtest86 (4.3.7-3) …
Generating grub configuration file …
Found background image: saint-John-of-Rila-grub.jpg
Found linux image: /boot/vmlinuz-4.19.0-18-amd64
Found initrd image: /boot/initrd.img-4.19.0-18-amd64
Found linux image: /boot/vmlinuz-4.19.0-17-amd64
Found initrd image: /boot/initrd.img-4.19.0-17-amd64
Found linux image: /boot/vmlinuz-4.19.0-8-amd64
Found initrd image: /boot/initrd.img-4.19.0-8-amd64
Found linux image: /boot/vmlinuz-4.19.0-6-amd64
Found initrd image: /boot/initrd.img-4.19.0-6-amd64
Found linux image: /boot/vmlinuz-4.19.0-5-amd64
Found initrd image: /boot/initrd.img-4.19.0-5-amd64
Found linux image: /boot/vmlinuz-4.9.0-8-amd64
Found initrd image: /boot/initrd.img-4.9.0-8-amd64
Found memtest86 image: /boot/memtest86.bin
Found memtest86+ image: /boot/memtest86+.bin
Found memtest86+ multiboot image: /boot/memtest86+_multiboot.bin
File descriptor 3 (pipe:[66049]) leaked on lvs invocation. Parent PID 22581: /bin/sh
done
Processing triggers for man-db (2.8.5-2) …

 

After this both memory testers memtest86+ and memtest86 will appear next to the option of booting a different version kernels and the Advanced recovery kernels, that you usually get in the GRUB boot prompt.

2.5. Use memtest embedded tool on any Linux by adding a kernel variable

Edit-Grub-Parameters-add-memtest-4-to-kernel-boot

2.4.1. Reboot your computer

# reboot

2.4.2. At the GRUB boot screen (with UEFI, press Esc).

2.4.3 For 4 passes add temporarily the memtest=4 kernel parameter.
 

memtest=        [KNL,X86,ARM,PPC,RISCV] Enable memtest
                Format: <integer>
                default : 0 <disable>
                Specifies the number of memtest passes to be
                performed. Each pass selects another test
                pattern from a given set of patterns. Memtest
                fills the memory with this pattern, validates
                memory contents and reserves bad memory
                regions that are detected.


3. Install and use memtester Linux tool
 

At some condition, memory is the one of the suspcious part, or you just want have a quick test. memtester  is an effective userspace tester for stress-testing the memory subsystem.  It is very effective at finding intermittent and non-deterministic faults.

The advantage of memtester "live system check tool is", you can check your system for errors while it's still running. No need for a restart, just run that application, the downside is that some segments of memory cannot be thoroughfully tested as you already have much preloaded data in it to have the Operating Sytstem running, thus always when possible try to stick to rule to test the memory using memtest86+  from OS Boot Loader, after a clean Machine restart in order to clean up whole memory heap.

Anyhow for a general memory test on a Critical Legacy Server  (if you lets say don't have access to Remote Console Board, or don't trust the ILO / IPMI Hardware reported integrity statistics), running memtester from already booted is still a good idea.


3.1. Install memtester on any Linux distribution from source

wget http://pyropus.ca/software/memtester/old-versions/memtester-4.2.2.tar.gz
# tar zxvf memtester-4.2.2.tar.gz
# cd memtester-4.2.2
# make && make install

3.2 Install on RPM based distros

 

On Fedora memtester is available from repositories however on many other RPM based distros it is not so you have to install it from source.

[root@fedora ]# yum install -y memtester

 

3.3. Install memtester on Deb based Linux distributions from source
 

To install it on Debian / Ubuntu / Mint etc. , open a terminal and type:
 

root@linux:/ #  apt install –yes memtester

The general run syntax is:

memtester [-p PHYSADDR] [ITERATIONS]


You can hence use it like so:

hipo@linux:/ $ sudo memtester 1024 5

This should allocate 1024MB of memory, and repeat the test 5 times. The more repeats you run the better, but as a memtester run places a great overall load on the system you either don't increment the runs too much or at least run it with  lowered process importance e.g. by nicing the PID:

hipo@linux:/ $ nice -n 15 sudo memtester 1024 5

 

  • If you have more RAM like 4GB or 8GB, it is upto you how much memory you want to allocate for testing.
  • As your operating system, current running process might take some amount of RAM, Please check available Free RAM and assign that too memtester.
  • If you are using a 32 Bit System, you cant test more than 4 GB even though you have more RAM( 32 bit systems doesnt support more than 3.5 GB RAM as you all know).
  • If your system is very busy and you still assigned higher than available amount of RAM, then the test might get your system into a deadlock, leads to system to halt, be aware of this.
  • Run the memtester as root user, so that memtester process can malloc the memory, once its gets hold on that memory it will try to apply lock. if specified memory is not available, it will try to reduce required RAM automatically and try to lock it with mlock.
  • if you run it as a regular user, it cant auto reduce the required amount of RAM, so it cant lock it, so it tries to get hold on that specified memory and starts exhausting all system resources.


If you have 8 Gigas of RAM plugged into the PC motherboard you have to multiple 1024*8 this is easily done with bc (An arbitrary precision calculator language) tool:

root@linux:/ # bc -l
bc 1.07.1
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
8*1024
8192


 for example you should run:

root@linux:/ # memtester 8192 5

memtester version 4.3.0 (64-bit)
Copyright (C) 2001-2012 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).

pagesize is 4096
pagesizemask is 0xfffffffffffff000
want 8192MB (2083520512 bytes)
got  8192MB (2083520512 bytes), trying mlock …Loop 1/1:
  Stuck Address       : ok        
  Random Value        : ok
  Compare XOR         : ok
  Compare SUB         : ok
  Compare MUL         : ok
  Compare DIV         : ok
  Compare OR          : ok
  Compare AND         : ok
  Sequential Increment: ok
  Solid Bits          : ok        
  Block Sequential    : ok        
  Checkerboard        : ok        
  Bit Spread          : ok        
  Bit Flip            : ok        
  Walking Ones        : ok        
  Walking Zeroes      : ok        
  8-bit Writes        : ok
  16-bit Writes       : ok

Done.

 

4. Shell Script to test server memory for corruptions
 

If for some reason the machine you want to run a memory test doesn't have connection to the external network such as the internet and therefore you cannot configure a package repository server and install memtester, the other approach is to use a simple memory test script such as memtestlinux.sh
 

#!/bin/bash
# Downloaded from https://www.srv24x7.com/memtest-linux/
echo "ByteOnSite Memory Test"
cpus=`cat /proc/cpuinfo | grep processor | wc -l`
if [ $cpus -lt 6 ]; then
threads=2
else
threads=$(($cpus / 2))
fi
echo "Detected $cpus CPUs, using $threads threads.."
memory=`free | grep 'Mem:' | awk {'print $2'}`
memoryper=$(($memory / $threads))
echo "Detected ${memory}K of RAM ($memoryper per thread).."
freespace=`df -B1024 . | tail -n1 | awk {'print $4'}`
if [ $freespace -le $memory ]; then
echo You do not have enough free space on the current partition. Minimum: $memory bytes
exit 1
fi
echo "Clearing RAM Cache.."
sync; echo 3 > /proc/sys/vm/drop_cachesfile
echo > dump.memtest.img
echo "Writing to dump file (dump.memtest.img).."
for i in `seq 1 $threads`;
do
# 1044 is used in place of 1024 to ensure full RAM usage (2% over allocation)
dd if=/dev/urandom bs=$memoryper count=1044 >> dump.memtest.img 2>/dev/null &
pids[$i]=$!
echo $i
done
for pid in "${pids[@]}"
do
wait $pid
done

echo "Reading and analyzing dump file…"
echo "Pass 1.."
md51=`md5sum dump.memtest.img | awk {'print $1'}`
echo "Pass 2.."
md52=`md5sum dump.memtest.img | awk {'print $1'}`
echo "Pass 3.."
md53=`md5sum dump.memtest.img | awk {'print $1'}`
if [ “$md51” != “$md52” ]; then
fail=1
elif [ “$md51” != “$md53” ]; then
fail=1
elif [ “$md52” != “$md53” ]; then
fail=1
else
fail=0
fi
if [ $fail -eq 0 ]; then
echo "Memory test PASSED."
else
echo "Memory test FAILED. Bad memory detected."
fi
rm -f dump.memtest.img
exit $fail

Nota Bene !: Again consider the restults might not always be 100% trustable if possible restart the server and test with memtest86+

Consider also its important to make sure prior to script run,  you''ll have enough disk space to produce the dump.memtest.img file – file is created as a test bed for the memory tests and if not scaled properly you might end up with a full ( / ) root directory!

 

4.1 Other memory test script with dd and md5sum checksum

I found this solution on the well known sysadmin site nixCraft cyberciti.biz, I think it makes sense and quicker.

First find out memory site using free command.
 

# free
             total       used       free     shared    buffers     cached
Mem:      32867436   32574160     293276          0      16652   31194340
-/+ buffers/cache:    1363168   31504268
Swap:            0          0          0


It shows that this server has 32GB memory,
 

# dd if=/dev/urandom bs=32867436 count=1050 of=/home/memtest


free reports by k and use 1050 is to make sure file memtest is bigger than physical memory.  To get better performance, use proper bs size, for example 2048 or 4096, depends on your local disk i/o,  the rule is to make bs * count > 32 GB.
run

# md5sum /home/memtest; md5sum /home/memtest; md5sum /home/memtest


If you see md5sum mismatch in different run, you have faulty memory guaranteed.
The theory is simple, the file /home/memtest will cache data in memory by filling up all available memory during read operation. Using md5sum command you are reading same data from memory.


5. Other ways to test memory / do a machine stress test

Other good tools you might want to check for memory testing is mprime – ftp://mersenne.org/gimps/ 
(https://www.mersenne.org/ftp_root/gimps/)

  •  (mprime can also be used to stress test your CPU)

Alternatively, use the package stress-ng to run all kind of stress tests (including memory test) on your machine.
Perhaps there are other interesting tools for a diagnosis of memory if you know other ones I miss, let me know in the comment section.

Install and configure rkhunter for improved security on a PCI DSS Linux / BSD servers with no access to Internet

Wednesday, November 10th, 2021

install-and-configure-rkhunter-with-tightened-security-variables-rkhunter-logo

rkhunter or Rootkit Hunter scans systems for known and unknown rootkits. The tool is not new and most system administrators that has to mantain some good security servers perhaps already use it in their daily sysadmin tasks.

It does this by comparing SHA-1 Hashes of important files with known good ones in online databases, searching for default directories (of rootkits), wrong permissions, hidden files, suspicious strings in kernel modules, commmon backdoors, sniffers and exploits as well as other special tests mostly for Linux and FreeBSD though a ports for other UNIX operating systems like Solaris etc. are perhaps available. rkhunter is notable due to its inclusion in popular mainstream FOSS operating systems (CentOS, Fedora,Debian, Ubuntu etc.).

Even though rkhunter is not rapidly improved over the last 3 years (its last Official version release was on 20th of Febuary 2018), it is a good tool that helps to strengthen even further security and it is often a requirement for Unix servers systems that should follow the PCI DSS Standards (Payment Card Industry Data Security Standards).

Configuring rkhunter is a pretty straight forward if you don't have too much requirements but I decided to write this article for the reason there are fwe interesting options that you might want to adopt in configuration to whitelist any files that are reported as Warnings, as well as how to set a configuration that sets a stricter security checks than the installation defaults. 

1. Install rkhunter .deb / .rpm package depending on the Linux distro or BSD

  • If you have to place it on a Redhat based distro CentOS / Redhat / Fedora

[root@Centos ~]# yum install -y rkhunter

 

  • On Debian distros the package name is equevallent to install there exec usual:

root@debian:~# apt install –yes rkhunter

  • On FreeBSD / NetBSD or other BSD forks you can install it from the BSD "World" ports system or install it from a precompiled binary.

freebsd# pkg install rkhunter

One important note to make here is to have a fully functional Alarming from rkhunter, you will have to have a fully functional configured postfix / exim / qmail whatever mail server to relay via official SMTP so you the Warning Alarm emails be able to reach your preferred Alarm email address. If you haven't installed postfix for example and configure it you might do.

– On Deb based distros 

[root@Centos ~]#yum install postfix


– On RPM based distros

root@debian:~# apt-get install –yes postfix


and as minimum, further on configure some functional Email Relay server within /etc/postfix/main.cf
 

# vi /etc/postfix/main.cf
relayhost = [relay.smtp-server.com]

2. Prepare rkhunter.conf initial configuration


Depending on what kind of files are present on the filesystem it could be for some reasons some standard package binaries has to be excluded for verification, because they possess unusual permissions because of manual sys admin monification this is done with the rkhunter variable PKGMGR_NO_VRFY.

If remote logging is configured on the system via something like rsyslog you will want to specificly tell it to rkhunter so this check as a possible security issue is skipped via ALLOW_SYSLOG_REMOTE_LOGGING=1. 

In case if remote root login via SSH protocol is disabled via /etc/ssh/sshd_config
PermitRootLogin no variable, the variable to include is ALLOW_SSH_ROOT_USER=no

It is useful to also increase the hashing check algorithm for security default one SHA256 you might want to change to SHA512, this is done via rkhunter.conf var HASH_CMD=SHA512

Triggering new email Warnings has to be configured so you receive, new mails at a preconfigured mailbox of your choice via variable
MAIL-ON-WARNING=SetMailAddress

 

# vi /etc/rkhunter.conf

PKGMGR_NO_VRFY=/usr/bin/su

PKGMGR_NO_VRFY=/usr/bin/passwd

ALLOW_SYSLOG_REMOTE_LOGGING=1

# Needed for corosync/pacemaker since update 19.11.2020

ALLOWDEVFILE=/dev/shm/qb-*/qb-*

# enabled ssh root access skip

ALLOW_SSH_ROOT_USER=no

HASH_CMD=SHA512

# Email address to sent alert in case of Warnings

MAIL-ON-WARNING=Your-Customer@Your-Email-Server-Destination-Address.com

MAIL-ON-WARNING=Your-Second-Peronsl-Email-Address@SMTP-Server.com

DISABLE_TESTS=os_specific


Optionally if you're using something specific such as corosync / pacemaker High Availability cluster or some specific software that is creating /dev/ files identified as potential Risks you might want to add more rkhunter.conf options like:
 

# Allow PCS/Pacemaker/Corosync
ALLOWDEVFILE=/dev/shm/qb-attrd-*
ALLOWDEVFILE=/dev/shm/qb-cfg-*
ALLOWDEVFILE=/dev/shm/qb-cib_rw-*
ALLOWDEVFILE=/dev/shm/qb-cib_shm-*
ALLOWDEVFILE=/dev/shm/qb-corosync-*
ALLOWDEVFILE=/dev/shm/qb-cpg-*
ALLOWDEVFILE=/dev/shm/qb-lrmd-*
ALLOWDEVFILE=/dev/shm/qb-pengine-*
ALLOWDEVFILE=/dev/shm/qb-quorum-*
ALLOWDEVFILE=/dev/shm/qb-stonith-*
ALLOWDEVFILE=/dev/shm/pulse-shm-*
ALLOWDEVFILE=/dev/md/md-device-map
# Needed for corosync/pacemaker since update 19.11.2020
ALLOWDEVFILE=/dev/shm/qb-*/qb-*

# tomboy creates this one
ALLOWDEVFILE="/dev/shm/mono.*"
# created by libv4l
ALLOWDEVFILE="/dev/shm/libv4l-*"
# created by spice video
ALLOWDEVFILE="/dev/shm/spice.*"
# created by mdadm
ALLOWDEVFILE="/dev/md/autorebuild.pid"
# 389 Directory Server
ALLOWDEVFILE=/dev/shm/sem.slapd-*.stats
# squid proxy
ALLOWDEVFILE=/dev/shm/squid-cf*
# squid ssl cache
ALLOWDEVFILE=/dev/shm/squid-ssl_session_cache.shm
# Allow podman
ALLOWDEVFILE=/dev/shm/libpod*lock*

 

3. Set the proper mirror database URL location to internal network repository

 

Usually  file /var/lib/rkhunter/db/mirrors.dat does contain Internet server address where latest version of mirrors.dat could be fetched, below is how it looks by default on Debian 10 Linux.

root@debian:/var/lib/rkhunter/db# cat mirrors.dat 
Version:2007060601
mirror=http://rkhunter.sourceforge.net
mirror=http://rkhunter.sourceforge.net

As you can guess a machine that doesn't have access to the Internet neither directly, neither via some kind of secure proxy because it is in a Paranoic Demilitarized Zone (DMZ) Network with many firewalls. What you can do then is setup another Mirror server (Apache / Nginx) within the local PCI secured LAN that gets regularly the database from official database on http://rkhunter.sourceforge.net/ (by installing and running rkhunter –update command on the Mirror WebServer and copying data under some directory structure on the remote local LAN accessible server, to keep the DB uptodate you might want to setup a cron to periodically copy latest available rkhunter database towards the http://mirror-url/path-folder/)

# vi /var/lib/rkhunter/db/mirrors.dat

local=http://rkhunter-url-mirror-server-url.com/rkhunter/1.4/


A mirror copy of entire db files from Debian 10.8 ( Buster ) ready for download are here.

Update entire file property db and check for rkhunter db updates

 

# rkhunter –update && rkhunter –propupdate

[ Rootkit Hunter version 1.4.6 ]

Checking rkhunter data files…
  Checking file mirrors.dat                                  [ Skipped ]
  Checking file programs_bad.dat                             [ No update ]
  Checking file backdoorports.dat                            [ No update ]
  Checking file suspscan.dat                                 [ No update ]
  Checking file i18n/cn                                      [ No update ]
  Checking file i18n/de                                      [ No update ]
  Checking file i18n/en                                      [ No update ]
  Checking file i18n/tr                                      [ No update ]
  Checking file i18n/tr.utf8                                 [ No update ]
  Checking file i18n/zh                                      [ No update ]
  Checking file i18n/zh.utf8                                 [ No update ]
  Checking file i18n/ja                                      [ No update ]

 

rkhunter-update-propupdate-screenshot-centos-linux


4. Initiate a first time check and see whether something is not triggering Warnings

# rkhunter –check

rkhunter-checking-for-rootkits-linux-screenshot

As you might have to run the rkhunter multiple times, there is annoying Press Enter prompt, between checks. The idea of it is that you're able to inspect what went on but since usually, inspecting /var/log/rkhunter/rkhunter.log is much more easier, I prefer to skip this with –skip-keypress option.

# rkhunter –check  –skip-keypress


5. Whitelist additional files and dev triggering false warnings alerts


You have to keep in mind many files which are considered to not be officially PCI compatible and potentially dangerous such as lynx browser curl, telnet etc. might trigger Warning, after checking them thoroughfully with some AntiVirus software such as Clamav and checking the MD5 checksum compared to a clean installed .deb / .rpm package on another RootKit, Virus, Spyware etc. Clean system (be it virtual machine or a Testing / Staging) machine you might want to simply whitelist the files which are incorrectly detected as dangerous for the system security.

Again this can be achieved with

PKGMGR_NO_VRFY=

Some Cluster softwares that are preparing their own /dev/ temporary files such as Pacemaker / Corosync might also trigger alarms, so you might want to suppress this as well with ALLOWDEVFILE

ALLOWDEVFILE=/dev/shm/qb-*/qb-*


If Warnings are found check what is the issue and if necessery white list files due to incorrect permissions in /etc/rkhunter.conf .

rkhunter-warnings-found-screenshot

Re-run the check until all appears clean as in below screenshot.

rkhunter-clean-report-linux-screenshot

Fixing Checking for a system logging configuration file [ Warning ]

If you happen to get some message like, message appears when rkhunter -C is done on legacy CentOS release 6.10 (Final) servers:

[13:45:29] Checking for a system logging configuration file [ Warning ]
[13:45:29] Warning: The 'systemd-journald' daemon is running, but no configuration file can be found.
[13:45:29] Checking if syslog remote logging is allowed [ Allowed ]

To fix it, you will have to disable SYSLOG_CONFIG_FILE at all.
 

SYSLOG_CONFIG_FILE=NONE

How to automate open xen Hypervisor Virtual Machines backups shell script

Tuesday, June 22nd, 2021

openxen-backup-logo As a sysadmin that have my own Open Xen Debian Hypervisor running on a Lenovo ThinkServer few months ago due to a human error I managed to mess up one of my virtual machines and rebuild the Operating System from scratch and restore files service and MySQl data from backup that really pissed me of and this brought the need for having a decent Virtual Machine OpenXen backup solution I can implement on the Debian ( Buster) 10.10 running the free community Open Xen version 4.11.4+107-gef32c7afa2-1. The Hypervisor is a relative small one holding just 7 VM s:

HypervisorHost:~#  xl list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0 11102    24     r—–  214176.4
pcfrxenweb                                  11 12288     4     -b—-  247425.5
pcfrxen                                     12 16384    10     -b—-  1371621.4
windows7                                    20  4096     2     -b—-   97887.2
haproxy2                                    21  4096     2     -b—-   11806.9
jitsi-meet                                  22  2048     2     -b—-   12843.9
zabbix                                      23  2048     2     -b—-   20275.1
centos7                                     24  2040     2     -b—-   10898.2

HypervisorHost:~# xl list|grep -v 'Name ' |grep  -v 'Domain-0'  |wc -l
7


The backup strategy of the script is very simple to shutdown the running VM machine, make a copy with rsync to a backup location the image of each of the Virtual Machines in a bash shell loop for each virtual machine shown in output of xl command and backup to a preset local directory in my case this is /backups/ the backup of each virtual machine is produced within a separate backup directory with a respective timestamp. Backup VM .img files are produced in my case to mounted 2x external attached hard drives each of which is a 4 Terabyte Seagate Plus Backup (Storage). The original version of the script was made to be a slightly different by Zhiqiang Ma whose script I used for a template to come up with my xen VM backup solution. To prevent the Hypervisor's load the script is made to do it with a nice of (nice -n 10) this might be not required or you might want to modify it to better suit your needs. Below is the script itself you can fetch a copy of it /usr/sbin/xen_vm_backups.sh :

#!/bin/bash

# Author: Zhiqiang Ma (http://www.ericzma.com/)
# Modified to work with xl and OpenXen by Georgi Georgiev – https://pc-freak.net
# Original creation dateDec. 27, 2010
# Script takes all defined vms under xen_name_list and prepares backup of each
# after shutting down the machine prepares archive and copies archive in externally attached mounted /backup/disk1 HDD
# Latest update: 08.06.2021 G. Georgiev – hipo@pc-freak.net

mark_file=/backups/disk1/tmp/xen-bak-marker
log_file=/var/log/xen/backups/bak-$(date +%Y_%m_%d).log
err_log_file=/var/log/xen/backups/bak_err-$(date +%H_%M_%Y_%m_%d).log
xen_dir=/xen/domains
xen_vmconfig_dir=/etc/xen/
local_bak_dir=/backups/disk1/tmp
#bak_dir=xenbak@backup_host1:/lhome/xenbak
bak_dir=/backups/disk1/xen-backups/xen_images/$(date +%Y_%m_%d)/xen/domains
#xen_name_list="haproxy2 pcfrxenweb jitsi-meet zabbix windows7 centos7 pcfrxenweb pcfrxen"
xen_name_list="windows7 haproxy2 jitsi-meet zabbix centos7"

if [ ! -d /var/log/xen/backups ]; then
echo mkdir -p /var/log/xen/backups
 mkdir -p /var/log/xen/backups
fi

if [ ! -d $bak_dir ]; then
echo mkdir -p $bak_dir
 mkdir -p $bak_dir

fi


# check whether bak runned last week
if [ -e $mark_file ] ; then
        echo  rm -f $mark_file
 rm -f $mark_file
else
        echo  touch $mark_file
 touch $mark_file
  # exit 0
fi

# set std and stderr to log file
        echo mv $log_file $log_file.old
       mv $log_file $log_file.old
        echo mv $err_log_file $err_log_file.old
       mv $err_log_file $err_log_file.old
        echo "exec 2> $err_log_file"
       exec 2> $err_log_file
        echo "exec > $log_file"
       exec > $log_file


# check whether the VM is running
# We only backup running VMs

echo "*** Check alive VMs"

xen_name_list_tmp=""

for i in $xen_name_list
do
        echo "/usr/sbin/xl list > /tmp/tmp-xen-list"
        /usr/sbin/xl list > /tmp/tmp-xen-list
  grepinlist=`grep $i" " /tmp/tmp-xen-list`;
  if [[ “$grepinlist” == “” ]]
  then
    echo $i is not alive.
  else
    echo $i is alive.
    xen_name_list_tmp=$xen_name_list_tmp" "$i
  fi
done

xen_name_list=$xen_name_list_tmp

echo "Alive VM list:"

for i in $xen_name_list
do
   echo $i
done

echo "End alive VM list."

###############################
date
echo "*** Backup starts"

###############################
date
echo "*** Copy VMs to local disk"

for i in $xen_name_list
do
  date
  echo "Shutdown $i"
        echo  /usr/sbin/xl shutdown $i
        /usr/sbin/xl shutdown $i
        if [ $? != ‘0’ ]; then
                echo 'Not Xen Disk image destroying …';
                /usr/sbin/xl destroy $i
        fi
  sleep 30

  echo "Copy $i"
  echo "Copy to local_bak_dir: $local_bak_dir"
      echo /usr/bin/rsync -avhW –no-compress –progress $xen_dir/$i/{disk.img,swap.img} $local_bak_dir/$i/
     time /usr/bin/rsync -avhW –no-compress –progress $xen_dir/$i/{disk.img,swap.img} $local_bak_dir/$i/
      echo /usr/bin/rsync -avhW –no-compress –progress $xen_vmconfig_dir/$i.cfg $local_bak_dir/$i.cfg
     time /usr/bin/rsync -avhW –no-compress –progress $xen_vmconfig_dir/$i.cfg $local_bak_dir/$i.cfg
  date
  echo "Create $i"
  # with vmmem=1024"
  # /usr/sbin/xm create $xen_dir/vm.run vmid=$i vmmem=1024
          echo /usr/sbin/xl create $xen_vmconfig_dir/$i.cfg
          /usr/sbin/xl create $xen_vmconfig_dir/$i.cfg
## Uncomment if you need to copy with scp somewhere
###       echo scp $log_file $bak_dir/xen-bak-111.log
###      echo  /usr/bin/rsync -avhW –no-compress –progress $log_file $local_bak_dir/xen-bak-111.log
done

####################
date
echo "*** Compress local bak vmdisks"

for i in $xen_name_list
do
  date
  echo "Compress $i"
      echo tar -z -cfv $bak_dir/$i-$(date +%Y_%m_%d).tar.gz $local_bak_dir/$i-$(date +%Y_%m_%d) $local_bak_dir/$i.cfg
     time nice -n 10 tar -z -cvf $bak_dir/$i-$(date +%Y_%m_%d).tar.gz $local_bak_dir/$i/ $local_bak_dir/$i.cfg
    echo rm -vf $local_bak_dir/$i/ $local_bak_dir/$i.cfg
    rm -vrf $local_bak_dir/$i/{disk.img,swap.img}  $local_bak_dir/$i.cfg
done

####################
date
echo "*** Copy local bak vmdisks to remote machines"

copy_remote () {
for i in $xen_name_list
do
  date
  echo "Copy to remote: vm$i"
        echo  scp $local_bak_dir/vmdisk0-$i.tar.gz $bak_dir/vmdisk0-$i.tar.gz
done

#####################
date
echo "Backup finishes"
        echo scp $log_file $bak_dir/bak-111.log

}

date
echo "Backup finished"

 

Things to configure before start using using the script to prepare backups for you is the xen_name_list variable

#  directory skele where to store already prepared backups
bak_dir=/backups/disk1/xen-backups/xen_images/$(date +%Y_%m_%d)/xen/domains

# The configurations of the running Xen Virtual Machines
xen_vmconfig_dir=/etc/xen/
# a local directory that will be used for backup creation ( I prefer this directory to be on the backup storage location )
local_bak_dir=/backups/disk1/tmp
#bak_dir=xenbak@backup_host1:/lhome/xenbak
# the structure on the backup location where daily .img backups with be produced with rsync and tar archived with bzip2
bak_dir=/backups/disk1/xen-backups/xen_images/$(date +%Y_%m_%d)/xen/domains

# list here all the Virtual Machines you want the script to create backups of
xen_name_list="windows7 haproxy2 jitsi-meet zabbix centos7"

If you need the script to copy the backup of Virtual Machine images to external Backup server via Local Lan or to a remote Internet located encrypted connection with a passwordless ssh authentication (once you have prepared the Machines to automatically login without pass over ssh with specific user), you can uncomment the script commented section to adapt it to copy to remote host.

Once you have placed at place /usr/sbin/xen_vm_backups.sh use a cronjob to prepare backups on a regular basis, for example I use the following cron to produce a working copy of the Virtual Machine backups everyday.
 

# crontab -u root -l 

# create windows7 haproxy2 jitsi-meet centos7 zabbix VMs backup once a month
00 06 1,2,3,4,5,6,7,8,9,10,11,12 * * /usr/sbin/xen_vm_backups.sh 2>&1 >/dev/null


I do clean up virtual machines Images that are older than 95 days with another cron job

# crontab -u root -l

# Delete xen image files older than 95 days to clear up space from backup HDD
45 06 17 * * find /backups/disk1/xen-backups/xen_images* -type f -mtime +95 -exec rm {} \; 2>&1 >/dev/null

#### Delete xen config backups older than 1 year+3 days (368 days)
45 06 17 * * find /backups/disk1/xen-backups/xen_config* -type f -mtime +368 -exec rm {} \; 2>&1 >/dev/null

 

# Delete xen image files older than 95 days to clear up space from backup HDD
45 06 17 * * find /backups/disk1/xen-backups/xen_images* -type f -mtime +95 -exec rm {} \; 2>&1 >/dev/null

#### Delete xen config backups older than 1 year+3 days (368 days)
45 06 17 * * find /backups/disk1/xen-backups/xen_config* -type f -mtime +368 -exec rm {} \; 2>&1 >/dev/null

How to configure bond0 bonding and network bridging for KVM Virtual machines on Redhat / CentOS / Fedora Linux

Tuesday, February 16th, 2021

configure-bond0-bonding-channel-with-bridges-on-hypervisor-host-for-guest-KVM-virtual-machines-howto-sample-Hypervisor-Virtual-machines-pic
 1. Intro to Redhat RPM based distro /etc/sysconfig/network-scripts/* config vars shortly explained

On RPM based Linux distributions configuring network has a very specific structure. As a sysadmin just recently I had a task to configure Networking on 2 Machines to be used as Hypervisors so the servers could communicate normally to other Networks via some different intelligent switches that are connected to each of the interfaces of the server. The idea is the 2 redhat 8.3 machines to be used as  Hypervisor (HV) and each of the 2 HVs to each be hosting 2 Virtual guest Machines with preinstalled another set of Redhat 8.3 Ootpa. I've recently blogged on how to automate a bit installing the KVM Virtual machines with using predefined kickstart.cfg file.

The next step after install was setting up the network. Redhat has a very specific network configuration well known under /etc/sysconfig/network-scripts/ifcfg-eno*# or if you have configured the Redhats to fix the changing LAN card naming ens, eno, em1 to legacy eth0, eth1, eth2 on CentOS Linux – e.g. to be named as /etc/sysconfig/network-scripts/{ifcfg-eth0,1,2,3}.

The first step to configure the network from that point is to come up with some network infrastrcture that will be ready on the HV nodes server-node1 server-node2 for the Virtual Machines to be used by server-vm1, server-vm2.

Thus for the sake of myself and some others I decide to give here the most important recognized variables that can be placed inside each of the ifcfg-eth0,ifcfg-eth1,ifcfg-eth2 …

A standard ifcfg-eth0 confing would look something this:
 

[root@redhat1 :~ ]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
TYPE=Ethernet
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV4_FAILURE_FATAL=no
NAME=eth0
UUID=…
ONBOOT=yes
HWADDR=0e:a4:1a:b6:fc:86
IPADDR0=10.31.24.10
PREFIX0=23
GATEWAY0=10.31.24.1
DNS1=192.168.50.3
DNS2=10.215.105.3
DOMAIN=example.com
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes


Lets say few words to each of the variables to make it more clear to people who never configured Newtork on redhat without the help of some of the console ncurses graphical like tools such as nmtui or want to completely stop the Network-Manager to manage the network and thus cannot take the advantage of using nmcli (a command-line tool for controlling NetworkManager).

Here is a short description of each of above configuration parameters:

TYPE=device_type: The type of network interface device
BOOTPROTO=protocol: Where protocol is one of the following:

  • none: No boot-time protocol is used.
  • bootp: Use BOOTP (bootstrap protocol).
  • dhcp: Use DHCP (Dynamic Host Configuration Protocol).
  • static: if configuring static IP

EFROUTE|IPV6_DEFROUTE=answer

  • yes: This interface is set as the default route for IPv4|IPv6 traffic.
  • no: This interface is not set as the default route.

Usually most people still don't use IPV6 so better to disable that

IPV6INIT=answer: Where answer is one of the following:

  • yes: Enable IPv6 on this interface. If IPV6INIT=yes, the following parameters could also be set in this file:

IPV6ADDR=IPv6 address

IPV6_DEFAULTGW=The default route through the specified gateway

  • no: Disable IPv6 on this interface.

IPV4_FAILURE_FATAL|IPV6_FAILURE_FATAL=answer: Where answer is one of the following:

  • yes: This interface is disabled if IPv4 or IPv6 configuration fails.
  • no: This interface is not disabled if configuration fails.

ONBOOT=answer: Where answer is one of the following:

  • yes: This interface is activated at boot time.
  • no: This interface is not activated at boot time.

HWADDR=MAC-address: The hardware address of the Ethernet device
IPADDRN=address: The IPv4 address assigned to the interface
PREFIXN=N: Length of the IPv4 netmask value
GATEWAYN=address: The IPv4 gateway address assigned to the interface. Because an interface can be associated with several combinations of IP address, network mask prefix length, and gateway address, these are numbered starting from 0.
DNSN=address: The address of the Domain Name Servers (DNS)
DOMAIN=DNS_search_domain: The DNS search domain (this is the search Domain-name.com you usually find in /etc/resolv.conf)

Other interesting file that affects how routing is handled on a Redhat Linux is

/etc/sysconfig/network

[root@redhat1 :~ ]# cat /etc/sysconfig/network
# Created by anaconda
GATEWAY=10.215.105.

Having this gateway defined does add a default gateway

This file specifies global network settings. For example, you can specify the default gateway, if you want to apply some network settings such as routings, Alias IPs etc, that will be valid for all configured and active configuration red by systemctl start network scripts or the (the network-manager if such is used), just place it in that file.

Other files of intesresting to control how resolving is being handled on the server worthy to check are 

/etc/nsswitch.conf

and

/etc/hosts

If you want to set a preference of /etc/hosts being red before /etc/resolv.conf and DNS resolving for example you need to have inside it, below is default behavior of it.
 

root@redhat1 :~ ]#   grep -i hosts /etc/nsswitch.conf
#     hosts: files dns
#     hosts: files dns  # from user file
# Valid databases are: aliases, ethers, group, gshadow, hosts,
hosts:      files dns myhostname

As you can see the default order is to read first files (meaning /etc/hosts) and then the dns (/etc/resolv.conf)
hosts: files dns

Now with this short intro description on basic values accepted by Redhat's /etc/sysconfig/network-scripts/ifcfg* prepared configurations.


I will give a practical example of configuring a bond0 interface with 2 members which were prepared based on Redhat's Official documentation found in above URLs:

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/configuring_and_managing_networking/configuring-network-bonding_configuring-and-managing-networking
 

# Bonding on RHEL 7 documentation
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/networking_guide/sec-network_bonding_using_the_command_line_interface

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/networking_guide/sec-verifying_network_configuration_bonding_for_redundancy

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/s2-networkscripts-interfaces_network-bridge

# Network Bridge with Bond documentation
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/sec-Configuring_a_VLAN_over_a_Bond

https://docs.fedoraproject.org/en-US/Fedora/24/html/Networking_Guide/sec-Network_Bridge_with_Bond.html


2. Configuring a single bond connection on eth0 / eth2 and setting 3 bridge interfaces bond -> br0, br1 -> eth1, br2 -> eth2

The task on my machines was to set up from 4 lan cards one bonded interface as active-backup type of bond with bonded lines on eth0, eth2 and 3 other 2 eth1, eth2 which will be used for private communication network that is connected via a special dedicated Switches and Separate VLAN 50, 51 over a tagged dedicated gigabit ports.

As said the 2 Servers had each 4 Broadcom Network CARD interfaces each 2 of which are paired (into a single card) and 2 of which are a solid Broadcom NetXtreme Dual Port 10GbE SFP+ and Dell Broadcom 5720 Dual Port 1Gigabit Network​.

2-ports-broadcom-netxtreme-dual-port-10GBe-spf-plus

On each of server-node1 and server-node2 we had 4 Ethernet Adapters properly detected on the Redhat

root@redhat1 :~ ]# lspci |grep -i net
01:00.0 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM5720 2-port Gigabit Ethernet PCIe
01:00.1 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM5720 2-port Gigabit Ethernet PCIe
19:00.0 Ethernet controller: Broadcom Inc. and subsidiaries BCM57412 NetXtreme-E 10Gb RDMA Ethernet Controller (rev 01)
19:00.1 Ethernet controller: Broadcom Inc. and subsidiaries BCM57412 NetXtreme-E 10Gb RDMA Ethernet Controller (rev 01)


I've already configured as prerogative net.ifnames=0 to /etc/grub2/boot.cfg and Network-Manager service disabled on the host (hence to not use Network Manager you'll see in below configuration NM_CONTROLLED="no" is telling the Redhat servers is not to be trying NetworkManager for more on that check my previous article Disable NetworkManager automatic Ethernet Interface Management on Redhat Linux , CentOS 6 / 7 / 8.

3. Types of Network Bonding

mode=0 (balance-rr)

This mode is based on Round-robin policy and it is the default mode. This mode offers fault tolerance and load balancing features. It transmits the packets in Round robin fashion that is from the first available slave through the last.

mode-1 (active-backup)

This mode is based on Active-backup policy. Only one slave is active in this band, and another one will act only when the other fails. The MAC address of this bond is available only on the network adapter part to avoid confusing the switch. This mode also provides fault tolerance.

mode=2 (balance-xor)

This mode sets an XOR (exclusive or) mode that is the source MAC address is XOR’d with destination MAC address for providing load balancing and fault tolerance. Each destination MAC address the same slave is selected.

mode=3 (broadcast)

This method is based on broadcast policy that is it transmitted everything on all slave interfaces. It provides fault tolerance. This can be used only for specific purposes.

mode=4 (802.3ad)

This mode is known as a Dynamic Link Aggregation mode that has it created aggregation groups having same speed. It requires a switch that supports IEEE 802.3ad dynamic link. The slave selection for outgoing traffic is done based on a transmit hashing method. This may be changed from the XOR method via the xmit_hash_policy option.

mode=5 (balance-tlb)

This mode is called Adaptive transmit load balancing. The outgoing traffic is distributed based on the current load on each slave and the incoming traffic is received by the current slave. If the incoming traffic fails, the failed receiving slave is replaced by the MAC address of another slave. This mode does not require any special switch support.

mode=6 (balance-alb)

This mode is called adaptive load balancing. This mode does not require any special switch support.

Lets create the necessery configuration for the bond and bridges

[root@redhat1 :~ ]# cat ifcfg-bond0
DEVICE=bond0
NAME=bond0
TYPE=Bond
BONDING_MASTER=yes
#IPADDR=10.50.21.16
#PREFIX=26
#GATEWAY=10.50.0.1
#DNS1=172.20.88.2
ONBOOT=yes
BOOTPROTO=none
BONDING_OPTS="mode=1 miimon=100 primary=eth0"
NM_CONTROLLED="no"
BRIDGE=br0


[root@redhat1 :~ ]# cat ifcfg-bond0.10
DEVICE=bond0.10
BOOTPROTO=none
ONPARENT=yes
#IPADDR=10.50.21.17
#NETMASK=255.255.255.0
VLAN=yes

[root@redhat1 :~ ]# cat ifcfg-br0
STP=yes
BRIDGING_OPTS=priority=32768
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
#IPV6INIT=yes
#IPV6_AUTOCONF=yes
#IPV6_DEFROUTE=yes
#IPV6_FAILURE_FATAL=no
#IPV6_ADDR_GEN_MODE=stable-privacy
IPV6_AUTOCONF=no
IPV6_DEFROUTE=no
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br0
UUID=4451286d-e40c-4d8c-915f-7fc12a16d595
DEVICE=br0
ONBOOT=yes
IPADDR=10.50.50.16
PREFIX=26
GATEWAY=10.50.0.1
DNS1=172.20.0.2
NM_CONTROLLED=no

[root@redhat1 :~ ]# cat ifcfg-br1
STP=yes
BRIDGING_OPTS=priority=32768
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=no
IPV4_FAILURE_FATAL=no
#IPV6INIT=yes
#IPV6_AUTOCONF=yes
#IPV6_DEFROUTE=yes
#IPV6_FAILURE_FATAL=no
#IPV6_ADDR_GEN_MODE=stable-privacy
IPV6INIT=no
IPV6_AUTOCONF=no
IPV6_DEFROUTE=no
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br1
UUID=40360c3c-47f5-44ac-bbeb-77f203390d29
DEVICE=br1
ONBOOT=yes
##IPADDR=10.50.51.241
PREFIX=28
##GATEWAY=10.50.0.1
##DNS1=172.20.0.2
NM_CONTROLLED=no

[root@redhat1 :~ ]# cat ifcfg-br2
STP=yes
BRIDGING_OPTS=priority=32768
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=no
IPV4_FAILURE_FATAL=no
#IPV6INIT=yes
#IPV6_AUTOCONF=yes
#IPV6_DEFROUTE=yes
#IPV6_FAILURE_FATAL=no
#IPV6_ADDR_GEN_MODE=stable-privacy
IPV6INIT=no
IPV6_AUTOCONF=no
IPV6_DEFROUTE=no
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br2
UUID=fbd5c257-2f66-4f2b-9372-881b783276e0
DEVICE=br2
ONBOOT=yes
##IPADDR=10.50.51.243
PREFIX=28
##GATEWAY=10.50.0.1
##DNS1=172.20.10.1
NM_CONTROLLED=no
NM_CONTROLLED=no
BRIDGE=br0

[root@redhat1 :~ ]# cat ifcfg-eth0
TYPE=Ethernet
NAME=bond0-slaveeth0
BOOTPROTO=none
#UUID=61065574-2a9d-4f16-b16e-00f495e2ee2b
DEVICE=eth0
ONBOOT=yes
MASTER=bond0
SLAVE=yes
NM_CONTROLLED=no

[root@redhat1 :~ ]# cat ifcfg-eth1
TYPE=Ethernet
NAME=eth1
UUID=b4c359ae-7a13-436b-a904-beafb4edee94
DEVICE=eth1
ONBOOT=yes
BRIDGE=br1
NM_CONTROLLED=no

[root@redhat1 :~ ]#  cat ifcfg-eth2
TYPE=Ethernet
NAME=bond0-slaveeth2
BOOTPROTO=none
#UUID=821d711d-47b9-490a-afe7-190811578ef7
DEVICE=eth2
ONBOOT=yes
MASTER=bond0
SLAVE=yes
NM_CONTROLLED=no

[root@redhat1 :~ ]#  cat ifcfg-eth3
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
#BOOTPROTO=dhcp
BOOTPROTO=none
DEFROUTE=no
IPV4_FAILURE_FATAL=no
#IPV6INIT=yes
#IPV6_AUTOCONF=yes
#IPV6_DEFROUTE=yes
#IPV6_FAILURE_FATAL=no
#IPV6_ADDR_GEN_MODE=stable-privacy
IPV6INIT=no
IPV6_AUTOCONF=no
IPV6_DEFROUTE=no
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
BRIDGE=br2
NAME=eth3
UUID=61065574-2a9d-4f16-b16e-00f495e2ee2b
DEVICE=eth3
ONBOOT=yes
NM_CONTROLLED=no

[root@redhat2 :~ ]# cat ifcfg-bond0
DEVICE=bond0
NAME=bond0
TYPE=Bond
BONDING_MASTER=yes
#IPADDR=10.50.21.16
#PREFIX=26
#GATEWAY=10.50.21.1
#DNS1=172.20.88.2
ONBOOT=yes
BOOTPROTO=none
BONDING_OPTS="mode=1 miimon=100 primary=eth0"
NM_CONTROLLED="no"
BRIDGE=br0

# cat ifcfg-bond0.10
DEVICE=bond0.10
BOOTPROTO=none
ONPARENT=yes
#IPADDR=10.50.21.17
#NETMASK=255.255.255.0
VLAN=yes
NM_CONTROLLED=no
BRIDGE=br0

[root@redhat2 :~ ]# cat ifcfg-br0
STP=yes
BRIDGING_OPTS=priority=32768
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
#IPV6INIT=yes
#IPV6_AUTOCONF=yes
#IPV6_DEFROUTE=yes
#IPV6_FAILURE_FATAL=no
#IPV6_ADDR_GEN_MODE=stable-privacy
IPV6_AUTOCONF=no
IPV6_DEFROUTE=no
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br0
#UUID=f87e55a8-0fb4-4197-8ccc-0d8a671f30d0
UUID=4451286d-e40c-4d8c-915f-7fc12a16d595
DEVICE=br0
ONBOOT=yes
IPADDR=10.50.21.17
PREFIX=26
GATEWAY=10.50.21.1
DNS1=172.20.88.2
NM_CONTROLLED=no

[root@redhat2 :~ ]#  cat ifcfg-br1
STP=yes
BRIDGING_OPTS=priority=32768
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=no
IPV4_FAILURE_FATAL=no
#IPV6INIT=no
#IPV6_AUTOCONF=no
#IPV6_DEFROUTE=no
#IPV6_FAILURE_FATAL=no
#IPV6_ADDR_GEN_MODE=stable-privacy
IPV6INIT=no
IPV6_AUTOCONF=no
IPV6_DEFROUTE=no
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br1
UUID=40360c3c-47f5-44ac-bbeb-77f203390d29
DEVICE=br1
ONBOOT=yes
##IPADDR=10.50.21.242
PREFIX=28
##GATEWAY=10.50.21.1
##DNS1=172.20.88.2
NM_CONTROLLED=no

[root@redhat2 :~ ]# cat ifcfg-br2
STP=yes
BRIDGING_OPTS=priority=32768
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=no
IPV4_FAILURE_FATAL=no
#IPV6INIT=no
#IPV6_AUTOCONF=no
#IPV6_DEFROUTE=no
#IPV6_FAILURE_FATAL=no
#IPV6_ADDR_GEN_MODE=stable-privacy
IPV6INIT=no
IPV6_AUTOCONF=no
IPV6_DEFROUTE=no
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br2
UUID=fbd5c257-2f66-4f2b-9372-881b783276e0
DEVICE=br2
ONBOOT=yes
##IPADDR=10.50.21.244
PREFIX=28
##GATEWAY=10.50.21.1
##DNS1=172.20.88.2
NM_CONTROLLED=no

[root@redhat2 :~ ]# cat ifcfg-eth0
TYPE=Ethernet
NAME=bond0-slaveeth0
BOOTPROTO=none
#UUID=ee950c07-7eb2-463b-be6e-f97e7ad9d476
DEVICE=eth0
ONBOOT=yes
MASTER=bond0
SLAVE=yes
NM_CONTROLLED=no

[root@redhat2 :~ ]# cat ifcfg-eth1
TYPE=Ethernet
NAME=eth1
UUID=ffec8039-58f0-494a-b335-7a423207c7e6
DEVICE=eth1
ONBOOT=yes
BRIDGE=br1
NM_CONTROLLED=no

[root@redhat2 :~ ]# cat ifcfg-eth2
TYPE=Ethernet
NAME=bond0-slaveeth2
BOOTPROTO=none
#UUID=2c097475-4bef-47c3-b241-f5e7f02b3395
DEVICE=eth2
ONBOOT=yes
MASTER=bond0
SLAVE=yes
NM_CONTROLLED=no


Notice that the bond0 configuration does not have an IP assigned this is done on purpose as we're using the interface channel bonding together with attached bridge for the VM. Usual bonding on a normal physical hardware hosts where no virtualization use is planned is perhaps a better choice. If you however try to set up an IP address in that specific configuration shown here and you try to reboot the machine, you will end up with inacessible machine over the network like I did and you will need to resolve configuration via some kind of ILO / IDRAC interface.

4. Generating UUID for ethernet devices bridges and bonds

One thing to note is the command uuidgen you might need that to generate UID identificators to fit in the new network config files.

Example:
 

[root@redhat2 :~ ]#uuidgen br2
e7995e15-7f23-4ea2-80d6-411add78d703
[root@redhat2 :~ ]# uuidgen br1
05e0c339-5998-414b-b720-7adf91a90103
[root@redhat2 :~ ]# uuidgen br0
e6d7ff74-4c15-4d93-a150-ff01b7ced5fb


5. How to make KVM Virtual Machines see configured Network bridges (modify VM XML)

To make the Virtual machines installed see the bridges I had to

[root@redhat1 :~ ]#virsh edit VM_name1
[root@redhat1 :~ ]#virsh edit VM_name2

[root@redhat2 :~ ]#virsh edit VM_name1
[root@redhat2 :~ ]#virsh edit VM_name2

Find the interface network configuration and change it to something like:

    <interface type='bridge'>
      <mac address='22:53:00:56:5d:ac'/>
      <source bridge='br0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
    </interface>
    <interface type='bridge'>
      <mac address='22:53:00:2a:5f:01'/>
      <source bridge='br1'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
    </interface>
    <interface type='bridge'>
      <mac address='22:34:00:4a:1b:6c'/>
      <source bridge='br2'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x08' slot='0x00' function='0x0'/>
    </interface>


6. Testing the bond  is up and works fine

# ip addr show bond0
The result is the following:

 

4: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 52:54:00:cb:25:82 brd ff:ff:ff:ff:ff:ff


The bond should be visible in the normal network interfaces with ip address show or /sbin/ifconfig

 

# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)

Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: eth0
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0

Slave Interface: eth2
MII Status: up
Speed: 10000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:0c:29:ab:2a:fa
Slave queue ID: 0

 

According to the output eth0 is the active slave.

The active slaves device files (eth0 in this case) is found in virtual file system /sys/

# find /sys -name *eth0
/sys/devices/pci0000:00/0000:00:15.0/0000:03:00.0/net/eth0
/sys/devices/virtual/net/bond0/lower_eth0
/sys/class/net/eth0


You can remove a bond member say eth0 by 

 

 cd to the pci* directory
Example: /sys/devices/pci000:00/000:00:15.0

 

# echo 1 > remove


At this point the eth0 device directory structure that was previously located under /sys/devices/pci000:00/000:00:15.0 is no longer there.  It was removed and the device no longer exists as seen by the OS.

You can verify this is the case with a simple ifconfig which will no longer list the eth0 device.
You can also repeat the cat /proc/net/bonding/bond0 command from Step 1 to see that eth0 is no longer listed as active or available.
You can also see the change in the messages file.  It might look something like this:

2021-02-12T14:13:23.363414-06:00 redhat1  device eth0: device has been deleted
2021-02-12T14:13:23.368745-06:00 redhat1 kernel: [81594.846099] bonding: bond0: releasing active interface eth0
2021-02-12T14:13:23.368763-06:00 redhat1 kernel: [81594.846105] bonding: bond0: Warning: the permanent HWaddr of eth0 – 00:0c:29:ab:2a:f0 – is still in use by bond0. Set the HWaddr of eth0 to a different address to avoid conflicts.
2021-02-12T14:13:23.368765-06:00 redhat1 kernel: [81594.846132] bonding: bond0: making interface eth1 the new active one.

 

Another way to test the bonding is correctly switching between LAN cards on case of ethernet hardware failure is to bring down one of the 2 or more bonded interfaces, lets say you want to switch from active-backup from eth1 to eth2, do:
 

# ip link set dev eth0 down


That concludes the test for fail over on active slave failure.

7. Bringing bond updown (rescan) bond with no need for server reboot

You know bonding is a tedious stuff that sometimes breaks up badly so only way to fix the broken bond seems to be a init 6 (reboot) cmd but no actually that is not so.

You can also get the deleted device back with a simple pci rescan command:

# echo 1 > /sys/bus/pci/rescan


The eth0 interface should now be back
You can see that it is back with an ifconfig command, and you can verify that the bond sees it with this command:

# cat /proc/net/bonding/bond0


That concludes the test of the bond code seeing the device when it comes back again.

The same steps can be repeated only this time using the eth1 device and file structure to fail the active slave in the bond back over to eth0.

8. Testing the bond with ifenslave command (ifenslave command examples)

Below is a set of useful information to test the bonding works as expected with ifenslave command  comes from "iputils-20071127" package

– To show information of all the inerfaces

                  # ifenslave -a
                  # ifenslave –all-interfaces 

 

– To change the active slave

                  # ifenslave -c bond0 eth1
                  # ifenslave –change-active bond0 eth1 

 

– To remove the slave interface from the bonding device

                  # ifenslave -d eth1
                  # ifenslave –detach bond0 eth1 

 

– To show master interface info

                  # ifenslave bond0 

 

– To set the bond device down and automatically release all the slaves

                  # ifenslave bond1 down 

– To get the usage info

                  # ifenslave -u
                  # ifenslave –usage 

– To set to verbose mode

                  # ifenslave -v
                  # ifenslave –verbose 

9. Testing the bridge works fine

Historically over the years all kind of bridges are being handled with the brctl part of bridge-utils .deb / .rpm installable package.

The classical way to check a bridge is working is to do

# brctl show
# brctl show br0; brctl show br1; brctl show br2

# brctl showmacs br0
 

etc.

Unfortunately with redhat 8 this command is no longer available so to get information about configured bridges you need to use instead:

 

# bridge link show
3:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state forwarding priority 32 cost 100
4:eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state listening priority 32 cost 100


10. Troubleshooting network connectivity issues on bond bridges and LAN cards

Testing the bond connection and bridges can route proper traffic sometimes is a real hassle so here comes at help the good old tcpdump

If you end up with issues with some of the ethernet interfaces between HV1 and HV2 to be unable to talk to each other and you have some suspiciousness that some colleague from the network team has messed up a copper (UTP) cable or there is a connectivity fiber optics issues. To check the VLAN tagged traffic headers on the switch you can listen to each and every bond0 and br0, br1, br2 eth0, eth1, eth2, eth3 configured on the server like so:

# tcpdump -i bond0 -nn -e vlan


Some further investigation on where does a normal ICMP traffic flows once everything is setup is a normal thing to do, hence just try to route a normal ping via the different server interfaces:

# ping -I bond0 DSTADDR

# ping -i eth0 DSTADDR

# ping -i eth1 DSTADDR

# ping -i eth2 DSTADDR


After conducting the ping do the normal for network testing big ICMP packages (64k) ping to make sure there are no packet losses etc., e.g:

# ping -I eth3 -s 64536  DSTADDR


If for 10 – 20 seconds the ping does not return package losses then you should be good.

How to configure static DNS and Search domain for Redhat / CentOS and Redhat Linux

Wednesday, February 3rd, 2021

Fedora-Red-Hat-and-CentOS-fix-DNS-resolv-conf-automatically-deleted-records
In latest Redhat based OS-es Fedora / CentOS / Redhat etc. just like on many other Linux distributions, we have /etc/resolv.conf being overwritten by NetworkManager and / or systemd configurations setup which since some time has been introduced to be a "more sophisticated" (default)  so the file is being written by Network Manager / dhcp or systemd config. Though the idea is good, having other programs modify /etc/resolv.conf is a real pain in the ass especially as you end up with an empty file because some service has overwritten what you have placed in the file and the DNS records and Search Domain is deleted forever. If you're not aware of this "new cool" linux feature you might first think that it was a bug that has ovewritten /etc/resolv.conf but ok guys as Bill Gates loved to say "this is not a bug it is a feature", so any attemps you make to manually change /etc/resolv.conf will be soon gone 🙂

This is pretty annoying for old school sysadmins which like to just set the necessery Domain name server resolving

search Subdomain.SearchDomain.Com
nameserver xxx.xxx.xxx.xxx
nameserver yyy.yyy.yyy.yyy


However as said Nowdays if you just place the desired config with in /etc/resolv.conf on next Server reboot or Network restart (or next fetch of DHCP if the ethernet interface IPs are being obtained via DHCP protocol) you will end up in a situation with an empty /etc/resolv.conf  with one commented line reading:

[root@redhat ~]# cat /etc/resolv.conf
# Generated by NetworkManager

To make the DNS and Search Domain be always presented on any network restart or reboot on the server hence you will need to define  DNS1 DNS2 DNS3 etc. and SEARCH variable inside the network configuration files for Bridge or Network interfaces located in /etc/sysconfig/network-scripts/ifcfg-br0 /etc/sysconfig/network-scripts/ifcfg-eno1np0 etc.  that will automatically append above search / nameserver fields in /etc/resolv.conf on any NetworkManager or system restart.
Below is example with the variables added to a Network bridge configuration on Redhat 8.3 (Ootpa):

[root@redhat ~]# cat /etc/sysconfig/network-scripts/ifcfg-br0
STP=yes
BRIDGING_OPTS=priority=32768
TYPE=Bridge
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=br0
UUID=f87e54a8-0fc4-4197-8ccc-0d8a671f30d0
DEVICE=br0
ONBOOT=yes
IPADDR=10.10.51.16
PREFIX=26
GATEWAY=10.10.51.1

DNS1="172.80.11.2"
DNS2="172.80.11.3"
DNS3="172.80.11.4"
SEARCH="sub.search-domain.com"


To test the configuration does append proper records into /etc/resolv.conf on Network restart  or /sbin/reboot reload the network.

[root@redhat ~]# systemctl restart NetworkManager


The result is you should have a good looking resolv.conf as so

[root@redhat ~]#  cat /etc/resolv.conf
# Generated by NetworkManager
search sub.search-domain.com
nameserver 172.20.88.2
nameserver 172.20.88.3
nameserver 172.20.88.4

 

Install certbot on Debian, Ubuntu, CentOS, Fedora Linux 10 / Generate and use Apache / Nginx SSL Letsencrypt certificates

Monday, December 21st, 2020

letsencrypt certbot install on any linux distribution with apache or nginx webserver howto</a><p> Let's Encrypt is a free, automated, and open certificate authority brought to you by the nonprofit <a data-cke-saved-href=
Internet Security Research Group (ISRG). ISRG group gave initiative with the goal to "encrypt the internet", i.e. offer free alternative to the overpriced domani registrer sold certificates with the goal to make more people offer SSL / TSL Free secured connection line on their websites. 
ISRG group supported Letsencrypt non-profit certificate authority actrively by Internet industry standard giants such as Mozilla, Cisco, EFF (Electronic Frontier Foundation),  Facebook, Google Chrome, Amazon AWS, OVH Cloud, Redhat, VMWare, Github and many many of the leading companies in IT.

Letsencrpyt is aimed at automating the process designed to overcome manual creation, validation, signing, installation, and renewal of certificates for secure websites. I.e. you don't have to manually write on console complicated openssl command lines with passing on Certificate CSR /  KEY / PEM files etc and generate Self-Signed Untrusted Authority Certificates (noted in my previous article How to generate Self-Signed SSL Certificates with openssl or use similar process to pay money generate secret key and submit the key to third party authority through a their website webadmin  interface in order to Generate SSL brought by Godaddy or Other Certificate Authority.

But of course as you can guess there are downsides as you submit your private key automatically via letsencrypt set of SSL certificate automation domain scripts to a third party Certificate Authority which is at Letsencrypt.org. A security intrusion in their private key store servers might mean a catastrophy for your data as malicious stealer might be able to decrypt your data with some additional effort and see in plain text what is talking to your Apache / Nginx or Mail Server nevertheless the cert. Hence for a high standards such as PCI environments Letsencrypt as well as for the paranoid security freak admins,  who don't trust the mainstream letsencrypt is definitely not a choice. Anyways for most small and midsized businesses who doesn't hold too much of a top secret data and want a moderate level of security Letsencrypt is a great opportunity to try. But enough talk, lets get down to business.

How to install and use certbot on Debian GNU / Linux 10 Buster?
Certbot is not available from the Debian software repositories by default, but it’s possible to configure the buster-backports repository in your /etc/apt/sources.list file to allow you to install a backport of the Certbot software with APT tool.
 

1. Install certbot on Debian / Ubuntu Linux

 

root@webserver:/etc/apt# tail -n 1 /etc/apt/sources.list
deb http://ftp.debian.org/debian buster-backports main


If not there append the repositories to file:

 

  • Install certbot-nginx certbot-apache deb packages

root@webserver:/ # echo 'deb http://ftp.debian.org/debian buster-backports main' >> /etc/apt/sources.list

 

  • Install certbot-nginx certbot-apache deb packages

root@webserver:/ # apt update
root@webserver:/ # apt install certbot python-certbot-nginx python3-certbot-apache python-certbot-nginx-doc


This will install the /usr/bin/certbot python executable script which is used to register / renew / revoke / delete your domains certificates.
 

2. Install letsencrypt certbot client on CentOS / RHEL / Fedora and other Linux Distributions

 


For RPM based distributions and other Linux distributions you will have to install snap package (if not already installed) and use snap command :

 

 

[root@centos ~ :] # yum install snapd
systemctl enable –now snapd.socket

To enable classic snap support, enter the following to create a symbolic link between

[root@centos ~ :] # ln -s /var/lib/snapd/snap /snap

snap command lets you install, configure, refresh and remove snaps.  Snaps are packages that work across many different Linux distributions, enabling secure delivery and operation of the latest apps and utilities.

[root@centos ~ :] # snap install core; sudo snap refresh core

Logout from console or Xsession to make the snap update its $PATH definitions.

Then use snap universal distro certbot classic package

 [root@centos ~ :] # snap install –classic certbot
[root@centos ~ :] # ln -s /snap/bin/certbot /usr/bin/certbot
 

 

If you're having an XOrg server access on the RHEL / CentOS via Xming or other type of Xemulator you might check out also the snap-store as it contains a multitude of packages installable which are not usually available in RPM distros.

 [root@centos ~ :] # snap install snap-store


how-to-install-snap-applications-on-centos-rhel-linux-snap-store

snap-store is a powerful and via it you can install many non easily installable stuff on Linux such as eclipse famous development IDE, notepad++ , Discord, the so favourite for the Quality Assurance guy Protocol tester Postman etc.

  • Installing certbot to any distribution via acme.sh script

Another often preferred solution to Universally deploy  and upgrade an existing LetsEncrypt program to any Linux distribution (e.g. RHEL / CentOS / Fedora etc.) is the acme.sh script. To install acme you have to clone the repository and run the script with –install

P.S. If you don't have git installed yet do

root@webserver:/ # apt-get install –yes git


and then the usual git clone to fetch it at your side

# cd /root
# git clone https://github.com/acmesh-official/acme.sh
Cloning into 'acme.sh'…
remote: Enumerating objects: 71, done.
remote: Counting objects: 100% (71/71), done.
remote: Compressing objects: 100% (53/53), done.
remote: Total 12475 (delta 39), reused 38 (delta 18), pack-reused 12404
Receiving objects: 100% (12475/12475), 4.79 MiB | 6.66 MiB/s, done.
Resolving deltas: 100% (7444/7444), done.

# sh acme.sh –install


To later upgrade acme.sh to latest you can do

# sh acme.sh –upgrade


In order to renew a concrete existing letsencrypt certificiate

# sh acme.sh –renew domainname.com


To renew all certificates using acme.sh script

# ./acme.sh –renew-all

 

3. Generate Apache or NGINX Free SSL / TLS Certificate with certbot tool

Now lets generate a certificate for a domain running on Apache Webserver with a Website WebRoot directory /home/phpdev/public/www

 

root@webserver:/ # certbot –apache –webroot -w /home/phpdev/public/www/ -d your-domain-name.com -d your-domain-name.com

root@webserver:/ # certbot certonly –webroot -w /home/phpdev/public/www/ -d your-domain-name.com -d other-domain-name.com


As you see all the domains for which you will need to generate are passed on with -d option.

Once certificates are properly generated you can test it in a browser and once you're sure they work as expected usually you can sleep safe for the next 3 months ( 90 days) which is the default for TSL / SSL Letsencrypt certificates the reason behind of course is security.

 

4. Enable freshly generated letsencrypt SSL certificate in Nginx VirtualHost config

Go to your nginx VirtualHost configuration (i.e. /etc/nginx/sites-enabled/phpmyadmin.adzone.pro ) and inside chunk of config add after location { … } – 443 TCP Port SSL listener (as in shown in bolded configuration)
 

server {

….
   location ~ \.php$ {
      include /etc/nginx/fastcgi_params;
##      fastcgi_pass 127.0.0.1:9000;
      fastcgi_pass unix:/run/php/php7.3-fpm.sock;
      fastcgi_index index.php;
      fastcgi_param SCRIPT_FILENAME /usr/share/phpmyadmin$fastcgi_script_name;
   }
 

 

 

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/phpmyadmin.adzone.pro/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/phpmyadmin.adzone.pro/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

 

5. Enable new generated letsencrypt SSL certificate in Apache VirtualHost


In /etc/apache2/{sites-available,sites-enabled}/your-domain.com-ssl.conf you should have as a minimum a configuration setup like below:
 

 

NameVirtualHost *:443 <VirtualHost 123.123.123.12:443>
    ServerAdmin hipo@domain.com
    ServerName www.pc-freak.net
    ServerAlias www.your-domain.com wwww.your-domain.com your-domain.com
 
    HostnameLookups off
    DocumentRoot /var/www
    DirectoryIndex index.html index.htm index.php index.html.var

 

 

CheckSpelling on
SSLEngine on

    <Directory />
        Options FollowSymLinks
        AllowOverride All
        ##Order allow,deny
        ##allow from all
        Require all granted
    </Directory>
    <Directory /var/www>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
##      Order allow,deny
##      allow from all
Require all granted
    </Directory>

Include /etc/letsencrypt/options-ssl-apache.conf
SSLCertificateFile /etc/letsencrypt/live/your-domain.com/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/your-domain.com/privkey.pem
</VirtualHost>

 

6. Simulate a certificate regenerate with –dry-run

Soon before the 90 days period expiry approaches, it is a good idea to test how all installed Nginx webserver certficiates will be renewed and whether any issues are expected this can be done with the –dry-run option.

root@webserver:/ # certbot renew –dry-run

 

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
** DRY RUN: simulating 'certbot renew' close to cert expiry
**          (The test certificates below have not been saved.)

Congratulations, all renewals succeeded. The following certs have been renewed:
  /etc/letsencrypt/live/adzone.pro/fullchain.pem (success)
  /etc/letsencrypt/live/cdn.natsr.pro/fullchain.pem (success)
  /etc/letsencrypt/live/mail.adzone.pro/fullchain.pem (success)
  /etc/letsencrypt/live/natsr.pro-0001/fullchain.pem (success)
  /etc/letsencrypt/live/natsr.pro/fullchain.pem (success)
  /etc/letsencrypt/live/phpmyadmin.adzone.pro/fullchain.pem (success)
  /etc/letsencrypt/live/www.adzone.pro/fullchain.pem (success)
  /etc/letsencrypt/live/www.natsr.pro/fullchain.pem (success)
** DRY RUN: simulating 'certbot renew' close to cert expiry
**          (The test certificates above have not been saved.)
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

 

7. Renew a certificate from a multiple installed certificate list

In some time when you need to renew letsencrypt domain certificates you can list them and choose manually which one you want to renew.

root@webserver:/ # certbot –force-renewal
Saving debug log to /var/log/letsencrypt/letsencrypt.log

How would you like to authenticate and install certificates?
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
1: Apache Web Server plugin (apache)
2: Nginx Web Server plugin (nginx)
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Plugins selected: Authenticator nginx, Installer nginx

Which names would you like to activate HTTPS for?
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
1: adzone.pro
2: mail.adzone.pro
3: phpmyadmin.adzone.pro
4: www.adzone.pro
5: natsr.pro
6: cdn.natsr.pro
7: www.natsr.pro
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Select the appropriate numbers separated by commas and/or spaces, or leave input
blank to select all options shown (Enter 'c' to cancel): 3
Renewing an existing certificate
Deploying Certificate to VirtualHost /etc/nginx/sites-enabled/phpmyadmin.adzone.pro

Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
1: No redirect – Make no further changes to the webserver configuration.
2: Redirect – Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Redirecting all traffic on port 80 to ssl in /etc/nginx/sites-enabled/phpmyadmin.adzone.pro

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Your existing certificate has been successfully renewed, and the new certificate
has been installed.

The new certificate covers the following domains: https://phpmyadmin.adzone.pro

You should test your configuration at:
https://www.ssllabs.com/ssltest/analyze.html?d=phpmyadmin.adzone.pro
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

IMPORTANT NOTES:
 – Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/phpmyadmin.adzone.pro/fullchain.pem

   Your key file has been saved at:
   /etc/letsencrypt/live/phpmyadmin.adzone.pro/privkey.pem
   Your cert will expire on 2021-03-21. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot again
   with the "certonly" option. To non-interactively renew *all* of
   your certificates, run "certbot renew"
 – If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

 

8. Renew all present SSL certificates

root@webserver:/ # certbot renew

Processing /etc/letsencrypt/renewal/www.natsr.pro.conf
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Cert not yet due for renewal

 

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

The following certs are not due for renewal yet:
  /etc/letsencrypt/live/adzone.pro/fullchain.pem expires on 2021-03-01 (skipped)
  /etc/letsencrypt/live/cdn.natsr.pro/fullchain.pem expires on 2021-02-28 (skipped)
  /etc/letsencrypt/live/mail.adzone.pro/fullchain.pem expires on 2021-02-28 (skipped)
  /etc/letsencrypt/live/natsr.pro-0001/fullchain.pem expires on 2021-03-01 (skipped)
  /etc/letsencrypt/live/natsr.pro/fullchain.pem expires on 2021-02-25 (skipped)
  /etc/letsencrypt/live/phpmyadmin.adzone.pro/fullchain.pem expires on 2021-03-21 (skipped)
  /etc/letsencrypt/live/www.adzone.pro/fullchain.pem expires on 2021-02-28 (skipped)
  /etc/letsencrypt/live/www.natsr.pro/fullchain.pem expires on 2021-03-01 (skipped)
No renewals were attempted.
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

 

 

9. Renew all existing server certificates from a cron job


The certbot package will install a script under /etc/cron.d/certbot to be run that will attempt every 12 hours however from my experience
often this script is not going to work, the script looks similar to below:

# Upgrade all existing SSL certbot machine certificates

 

0 */12 * * * root test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e 'sleep int(rand(43200))' && certbot -q renew

Another approach to renew all installed certificates if you want to have a specific options and keep log of what happened is using a tiny shell script like this:

 

10. Auto renew installed SSL / TSL Certbot certificates with a bash loop over all present certificates

#!/bin/sh
# update SSL certificates
# prints from 1 to 104 (according to each certbot generated certificate and triggers rewew and logs what happened to log file
# an ugly hack for certbot certificate renew
for i in $(seq 1 104); do echo "Updating $i SSL Cert" | tee -a /root/certificate-update.log; yes "$i" | certbot –force-renewal | tee -a /root/certificate-update.log 2>&1; sleep 5; done

Note: The seq 1 104 is the range depends on the count of installed SSL certificates you have installed on the machine, that can be seen and set the proper value according to your case when you run one time certbot –force-renewal.
 

Report haproxy node switch script useful for Zabbix or other monitoring

Tuesday, June 9th, 2020

zabbix-monitoring-logo
For those who administer corosync clustered haproxy and needs to build monitoring in case if the main configured Haproxy node in the cluster is changed, I've developed a small script to be integrated with zabbix-agent installed to report to a central zabbix server via a zabbix proxy.
The script  is very simple it assumed DC1 variable is the default used haproxy node and DC2 and DC3 are 2 backup nodes. The script is made to use crm_mon which is not installed by default on each server by default so if you'll be using it you'll have to install it first, but anyways the script can easily be adapted to use pcs cmd instead.

Below is the bash shell script:

UserParameter=active.dc,f=0; for i in $(sudo /usr/sbin/crm_mon -n -1|grep -i 'Node ' |awk '{ print $2 }'); do ((f++)); DC[$f]="$i"; done; \
DC=$(sudo /usr/sbin/crm_mon -n -1 | grep 'Current DC' | awk '{ print $1 " " $2 " " $3}' | awk '{ print $3 }'); \
if [ “$DC” == “${DC[1]}” ]; then echo “1 Default DC Switched to ${DC[1]}”; elif [ “$DC” == “${DC[2]}” ]; then \
echo "2 Default DC Switched to ${DC[2]}”; elif [ “$DC” == “${DC[3]}” ]; then echo “3 Default DC: ${DC[3]}"; fi


To configure it with zabbix monitoring it can be configured via UserParameterScript.

The way I configured  it in Zabbix is as so:


1. Create the userpameter_active_node.conf

Below script is 3 nodes Haproxy cluster

# cat > /etc/zabbix/zabbix_agentd.d/userparameter_active_node.conf

UserParameter=active.dc,f=0; for i in $(sudo /usr/sbin/crm_mon -n -1|grep -i 'Node ' |awk '{ print $2 }'); do ((f++)); DC[$f]="$i"; done; \
DC=$(sudo /usr/sbin/crm_mon -n -1 | grep 'Current DC' | awk '{ print $1 " " $2 " " $3}' | awk '{ print $3 }'); \
if [ “$DC” == “${DC[1]}” ]; then echo “1 Default DC Switched to ${DC[1]}”; elif [ “$DC” == “${DC[2]}” ]; then \
echo "2 Default DC Switched to ${DC[2]}”; elif [ “$DC” == “${DC[3]}” ]; then echo “3 Default DC: ${DC[3]}"; fi

Once pasted to save the file press CTRL + D


The version of the script with 2 nodes slightly improved is like so:
 

UserParameter=active.dc,f=0; for i in $(sudo /usr/sbin/crm_mon -n -1|grep -i 'Node ' |awk '{ print $2 }' | sed -e 's#:##g'); do DC_ARRAY[$f]=”$i”; ((f++)); done; GET_CURR_DC=$(sudo /usr/sbin/crm_mon -n -1 | grep ‘Current DC’ | awk ‘{ print $1 ” ” $2 ” ” $3}’ | awk ‘{ print $3 }’); if [ “$GET_CURR_DC” == “${DC_ARRAY[0]}” ]; then echo “1 Default DC ${DC_ARRAY[0]}”; fi; if [ “$GET_CURR_DC” == “${DC_ARRAY[1]}” ]; then echo “2 Default Current DC Switched to ${DC_ARRAY[1]} Please check “; fi; if [ -z “$GET_CURR_DC” ] || [ -z “$DC_ARRAY[1]” ]; then printf "Error something might be wrong with HAProxy Cluster on  $HOSTNAME "; fi;


The haproxy_active_DC_zabbix.sh script with a bit of more comments as explanations is available here 
2. Configure access for /usr/sbin/crm_mon for zabbix user in sudoers

 

# vim /etc/sudoers

zabbix          ALL=NOPASSWD: /usr/sbin/crm_mon


3. Configure in Zabbix for active.dc key Trigger and Item

active-node-switch1

Fix FTP active connection issues “Cannot create a data connection: No route to host” on ProFTPD Linux dedicated server

Tuesday, October 1st, 2019

proftpd-linux-logo

Earlier I've blogged about an encounter problem that prevented Active mode FTP connections on CentOS
As I'm working for a client building a brand new dedicated server purchased from Contabo Dedi Host provider on a freshly installed Debian 10 GNU / Linux, I've had to configure a new FTP server, since some time I prefer to use Proftpd instead of VSFTPD because in my opinion it is more lightweight and hence better choice for a small UNIX server setups. During this once again I've encounted the same ACTIVE FTP not working from FTP server to FTP client host machine. But before shortly explaining, the fix I find worthy to explain briefly what is ACTIVE / PASSIVE FTP connection.

 

1. What is ACTIVE / PASSIVE FTP connection?
 

Whether in active mode, the client specifies which client-side port the data channel has been opened and the server starts the connection. Or in other words the default FTP client communication for historical reasons is in ACTIVE MODE. E.g.
Client once connected to Server tells the server to open extra port or ports locally via which the overall FTP data transfer will be occuring. In the early days of networking when FTP protocol was developed security was not of such a big concern and usually Networks did not have firewalls at all and the FTP DATA transfer host machine was running just a single FTP-server and nothing more in this, early days when FTP was not even used over the Internet and FTP DATA transfers happened on local networks, this was not a problem at all.

In passive mode, the server decides which server-side port the client should connect to. Then the client starts the connection to the specified port.

But with the ever increasing complexity of Internet / Networks and the ever tightening firewalls due to viruses and worms that are trying to own and exploit networks creating unnecessery bulk loads this has changed …

active-passive-ftp-explained-diagram
 

2. Installing and configure ProFTPD server Public ServerName

I've installed the server with the common cmd:

 

apt –yes install proftpd

 

And the only configuration changed in default configuration file /etc/proftpd/proftpd.conf  was
ServerName          "Debian"

I do this in new FTP setups for the logical reason to prevent the multiple FTP Vulnerability Scan script kiddie Crawlers to know the exact OS version of the server, so this was changed to:

 

ServerName "MyServerHostname"

 

Though this is the bad security through obscurity practice doing so is a good practice.
 

3. Create iptable firewall rules to allow ACTIVE FTP mode


But anyways, next step was to configure the firewall to be allowed to communicate on TCP PORT 21 and 20 to incoming source ports range 1024:65535 (to enable ACTIVE FTP) on firewal level with iptables on INPUT and OUTPUT chain rules, like this:

 

iptables -A INPUT -p tcp –sport 1024:65535 -d 0/0 –dport 21 -m state –state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp -s 0/0 –sport 1024:65535 -d 0/0 –dport 20 -m state –state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp -s 0/0 –sport 21 -d 0/0 –dport 1024:65535 -m state –state ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp -s 0/0 –sport 20 -d 0/0 –dport 1024:65535 -m state –state ESTABLISHED,RELATED -j ACCEPT


Talking about Active and Passive FTP connections perhaps for novice Linux users it might be worthy to say few words on Active and Passive FTP connections

Once firewall has enabled FTP Active / Passive connections is on and FTP server is listening, to test all is properly configured check iptable rules and FTP listener:
 

/sbin/iptables -L INPUT |grep ftp
ACCEPT     tcp  —  anywhere             anywhere             tcp spts:1024:65535 dpt:ftp state NEW,ESTABLISHED
ACCEPT     tcp  —  anywhere             anywhere             tcp spts:1024:65535 dpt:ftp-data state NEW,ESTABLISHED
ACCEPT     tcp  —  anywhere             anywhere             tcp dpt:ftp
ACCEPT     tcp  —  anywhere             anywhere             tcp dpt:ftp-data

netstat -l | grep "ftp"
tcp6       0      0 [::]:ftp                [::]:*                  LISTEN    

 

4. Loading nf_nat_ftp module and net.netfilter.nf_conntrack_helper (for backward compitability)


Next step of course was to add the necessery modules nf_nat_ftp nf_conntrack_sane that makes FTP to properly forward ports with respective Firewall states on any of above source ports which are usually allowed by firewalls, note that the range of ports given 1024:65535 might be too much liberal for paranoid sysadmins and in many cases if ports are not filtered, if you are a security freak you can use some smaller range such as 60000-65535.

 

Here is time to say for sysadmins who haven't recently had a task to configure a new (unecrypted) File Transfer Server as today Secure FTP is almost alltime used for file transfers for the sake of security might be puzzled to find out the old Linux kernel ip_conntrack_ftp which was the standard module used to make FTP Active connections work is substituted nowadays with  nf_nat_ftp and nf_conntrack_sane.

To make the 2 modules permanently loaded on next boot on Debian Linux they have to be added to /etc/modules

Here is how sample /etc/modules that loads the modules on next system boot looks like

cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
softdog
nf_nat_ftp
nf_conntrack_sane


Next to say is that in newer Linux kernels 3.x / 4.x / 5.x the nf_nat_ftp and nf_conntrack-sane behaviour changed so  simply loading the modules would not work and if you do the stupidity to test it with some FTP client (I used gFTP / ncftp from my Linux desktop ) you are about to get FTP No route to host errors like:

 

Cannot create a data connection: No route to host

 

cannot-create-a-data-connection-no-route-to-host-linux-error-howto-fix


Sometimes, instead of No route to host error the error FTP client might return is:

 

227 entering passive mode FTP connect connection timed out error


To make the nf_nat_ftp module on newer Linux kernels hence you have to enable backwards compatibility Kernel variable

 

 

/proc/sys/net/netfilter/nf_conntrack_helper

 

echo 1 > /proc/sys/net/netfilter/nf_conntrack_helper

 

To make it permanent if you have enabled /etc/rc.local legacy one single file boot place as I do on servers – for how to enable rc.local on newer Linuxes check here

or alternatively add it to load via sysctl

sysctl -w net.netfilter.nf_conntrack_helper=1

And to make change permanent (e.g. be loaded on next boot)

echo 'net.netfilter.nf_conntrack_helper=1' >> /etc/sysctl.conf

 

5. Enable PassivePorts in ProFTPD or PassivePortRange in PureFTPD


Last but not least open /etc/proftpd/proftpd.conf find PassivePorts config value (commented by default) and besides it add the following line:

 

PassivePorts 60000 65534

 

Just for information if instead of ProFTPd you experience the error on PureFTPD the configuration value to set in /etc/pure-ftpd.conf is:
 

PassivePortRange 30000 35000


That's all folks, give the ncftp / lftp / filezilla or whatever FTP client you prefer and test it the FTP client should be able to talk as expected to remote server in ACTIVE FTP mode (and the auto passive mode) will be not triggered anymore, nor you will get a strange errors and failure to connect in FTP clients as gftp.

Cheers 🙂

Mount remote Linux SSHFS Filesystem harddisk on Windows Explorer SWISH SSHFS file mounter and a short evaluation on what is available to copy files to SSHFS from Windows PC

Monday, February 22nd, 2016

swish-mount-and-copy-files-from-windows-to-linux-via-sshfs-mount

I'm forced to use Windows on my workbook and I found it really irritating, that I can't easily share files in a DropBox, Google Drive, MS OneDrive, Amazon Storage or other cloud-storage free remote service. etc.
I don't want to use DropBox like non self-hosted Data storage because I want to keep my data private and therefore the only and best option for me was to make possible share my Linux harddisk storage
dir remotely to the Windows notebook.

I didn't wanted to setup some complex environment such as Samba Share Server (which used to be often a common option to share file from Linux server to Windows), neither wanted to bother with  installing FTP service and bother with FTP clients, or configuring some other complex stuff such as WebDav – which BTW is an accepted and heavily used solution across corporate clients to access read / write files on a remote Linux servers.
Hence, I made a quick research what else besides could be used to easily share files and data from Windows PC / notebook to a home brew or professional hosting Linux server.

It turned out, there are few of softwares that gives a similar possibility for a home lan small network Linux / Windows hybrid network users such, here is few of the many:

  • SyncThingSyncthing is an open-source file synchronization client/server application, written in Go, implementing its own, equally free Block Exchange Protocol. The source code's content-management repository is hosted on GitHub

     

     

     

     

     

    syncthing-logo

  • OwnCloud – ownCloud provides universal access to your files via the web, your computer or your mobile devices

     

     

     

     

     

    owncloud-logo

  • Seafile – Seafile is a file hosting software system. Files are stored on a central server and can be synchronized with personal computers and mobile devices via the Seafile client. Files can also be accessed via the server's web interface


seafile-client-in-browser

I've checked all of them and give a quick try of Syncthing which is really easy to start, just download the binary launch it and configure it under https://Localhost:8385 URL from a browser on the Linux server.
Syncthing seemed to be nice and easy to configure solution to be able to Sync files between Server A (Windows) and Server B(Linux) and guess many would enjoy it, if you want to give it a try you can follow this short install syncthing article.
However what I didsliked in both SyncThing and OwnCloud and Seafile and all of the other Sync file solutions was, they only supported synchronization via web and didn't seemed to have a Windows Explorer integration and did required
the server to run more services, posing another security hole in the system as such third party softwares are not easily to update and maintain.

Because of that finally after rethinking about some other ways to copy files to a locally mounted Sync directory from the Linux server, I've decided to give SSHFS a try. Mounting SSHFS between two Linux / UNIX hosts is
quite easy task with SSHFS tool

In Windows however the only way I know to transfer files to Linux via SSHFS was with WinSCP client and other SCP clients as well as the experimental:

As well as few others such as ExpandDrive, Netdrive, Dokan SSHFS (mirrored for download here)
I should say that I first decided to try copying few dozen of Gigabyte movies, text, books etc. using WinSCP direct connection, but after getting a couple of timeouts I was tired of WinSCP and decided to look for better way to copy to remote Linux SSHFS.
However the best solution I found after a bit of extensive turned to be:

SWISH – Easy SFTP for Windows

Swish is very straight forward to configure compared to all of them you download the .exe which as of time of writting is at version 0.8.0 install on the PC and right in My Computer you will get a New Device called Swish next to your local and remote drives C:/ D:/ , USBs etc.

swish-new-device-to-appear-in-my-computer-to-mount-sshfs

As you see in below screenshot two new non-standard buttons will Appear in Windows Explorer that lets you configure SWISH

windows-mount-sshfs-swish-add-sftp-connection-button-screenshot

Next and final step before you have the SSHFS remote Linux filesystem visible on Windows Xp / 7 / 8 / 10 is to fill in remote Linux hostname address (or even better fill in IP to get rid of possible DNS issues), UserName (UserID) and Direcory to mount.

swish-new-fill-in-dialog-to-make-new-linux-sshfs-mount-directory-possible-on-windows

Then you will see the SSHFS moutned:

swish-sshfs-mounted-on-windows

You will be asked to accept the SSH host-key as it used to be unknown so far

swish-mount-sshfs-partition-on-windows-from-remote-linux-accept-key

That's it now you will see straight into Windows Explorer the remote Linux SSHFS mounted:

remote-sshfs-linux-filesystem-mounted-in-windows-explorer-with-swish

Once setupped a Swish connection to copy files directly to it you can use the Send to Embedded Windows dialog, as in below screenshot

swish-send-to-files-windows-screenshot

The only 3 problem with SWISH are:

1. It doesn't support Save password, so on every Windows PC reboot when you want to connect to remote Linux SSHFS, you will have to retype remote login user pass.
Fron security stand point this is not such a bad thing, but it is a bit irritating to everytime type the password without an option to save permanently.
The good thing here is you can use Launch Key Agent
as visible in above screenshot and set in Putty Key Agent your remote host SSH key so the passwordless login will work without any authentication at
all however, this might open a security hole if your Win PC gets infected by virus, which might delete something on remote mounted SSHFS filesystem so I personally prefer to retype password on every boot.

2. it is a bit slow so if you're planning to Transfer large amounts of Data as hundreds of megabytes, expect a very slow transfer rate, even in a Local  10Mbit Network to transfer 20 – 30 GB of data, it took me about 2-3 hours or so.
SWISH is not actively supported and it doesn't have new release since 20th of June 2013, but for the general work I need it is just perfect, as I don't tent to be Synchronizing Dozens of Gigabytes all the time between my notebook PC and the Linux server.

3. If you don't use the established mounted connection for a while or your computer goes to sleep mode after recovering your connection to remote Linux HDD if opened in Windows File Explorer will probably be dead and you will have to re-enable it.

For Mac OS X users who want to mount / attach remote directory from a Linux partitions should look in fuguA Mac OS X SFTP, SCP and SSH Frontend

I'll be glad to hear from people on other good ways to achieve same results as with SWISH but have a better copy speed while using SSHFS.