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Enable zabbix agent to work with SeLinux enabled on CentOS 7 Linux

Wednesday, October 19th, 2022

If you have the task to install and use zabbix-agent or zabbix-proxy to report to zabbix-server on CentOS 7 with enabled SeLinux services for security reasons and you have no mean to disable the selinux which is a common step to take under this circumstances, you will have to add the zabbix services to be exluded as permissive in selinux. In below article I'll show you how this is done in few easy steps.

zabbix-agent-service-selinux-linux-real-time-operating-sytems

 

1. Check the system sestatus

[root@linux zabbix]# sestatus
SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      28


2. Enable zabbix to be permissive in selinux

To be able to set zabbix to be in permissive mode as well as for further troubleshooting if you have to enable other  linux services inside selinux you have to install below RPM packs.

[root@linux zabbix]# yum install setroubleshoot.x86_64 setools.x86_64 setools-console.x86_64 policycoreutils-python.x86_64

Set the zabbix permissive exclude rule in SeLINUX

[root@linux zabbix]# semanage permissive –add zabbix_t

Re-run the zabbix proxy (if you have a local zabbix-proxy running and the zabbix-agent)

[root@linux zabbix]# systemctl start zabbix-proxy.service

[root@linux zabbix]# systemctl start zabbix-agent.service

[root@linux zabbix]# systemctl status zabbix-agent
● zabbix-agent.service – Zabbix Agent
   Loaded: loaded (/usr/lib/systemd/system/zabbix-agent.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2022-10-18 09:30:16 CEST; 1 day 7h ago
 Main PID: 962952 (zabbix_agentd)
    Tasks: 6 (limit: 100884)
   Memory: 5.1M
   CGroup: /system.slice/zabbix-agent.service
           ├─962952 /usr/sbin/zabbix_agentd -c /etc/zabbix/zabbix_agentd.conf
           ├─962955 /usr/sbin/zabbix_agentd: collector [idle 1 sec]
           ├─962956 /usr/sbin/zabbix_agentd: listener #1 [waiting for connection]
           ├─962957 /usr/sbin/zabbix_agentd: listener #2 [waiting for connection]
           ├─962958 /usr/sbin/zabbix_agentd: listener #3 [waiting for connection]
           └─962959 /usr/sbin/zabbix_agentd: active checks #1 [idle 1 sec]

Oct 18 09:30:16 linux systemd[1]: Starting Zabbix Agent…
Oct 18 09:30:16 linux systemd[1]: Started Zabbix Agent.

3. Check inside audit logs all is OK

To make sure zabbix is really enabled to be omitted by selinux rules check audit.log

[root@linux zabbix]# grep zabbix_proxy /var/log/audit/audit.log

That's all folks, Enjoy ! 🙂

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Posted in Migration, System Administration, Zabbix | No Comments »

How to create multiple haproxy instance separate processes for different configuration listeners with systemd on single Linux server

Tuesday, August 30th, 2022

HAProxy-Multiple-instanes-with-systemd-on-same-host-howto-Load-Balance-Your-Servers

In this aticle will be explained, howto configure multiple haproxy instances with separate haproxy binary wrappers and configs to run on the same Linux server host
by creating and using systemd additional .services.

Usually haproxy as installed and  ran standard on Linux swapns 2 listener processes which are configured to serve any proxy configuration setup inside /etc/haproxy/haproxy.cfg.

Here is example:

[root@haproxy2:~ ]# ps -ef|grep -i haproxy
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 ?        00:49:24 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -S /run/haproxy-master.sock

However what if you need to have a multiple services to be proxied and you need to have multiple configuration files separated under various
/etc/haproxy/ stored files (.e.g /etc/haproxy/haproxy-customer1.cfg /etc/haproxy-customer2.cfg /etc/haproxy-custmXYZ.fg) etc. , what then how this can be done ?

Besides the many down sides of involving systemd into Linux, there is some good sides of it, as on any modern Linux there is a separate service to manage haproxy as of year 2022 on most modern Linuxes Debian / CentOS / Redhat the location where usually systemd service scripts are located is under directory /usr/lib/systemd/system/ the systemd managed service files are with extension .service

[root@haproxy2:/usr/lib/systemd/system ]# ls -al haproxy.service
-rw-r–r– 1 root root 1509 Sep  5  2021 haproxy.service
[root@haproxy2:/usr/lib/systemd/system ]# ls -al cron.service
-rw-r–r– 1 root root 316 Feb 23  2021 cron.service
[root@haproxy2:/usr/lib/systemd/system ]# ls -al networking.service
-rw-r–r– 1 root root 643 Sep 21  2020 networking.service
[root@haproxy2:/usr/lib/systemd/system ]# ls -al systemd-journald.service
-rw-r–r– 1 root root 1812 Jul 13  2021 systemd-journald.service


1. Create new haproxy-custom.service and /etc/haproxy.cfg file copies
 

Adding new services that will be managed by systemd is pretty simple hence, you just need to have the original service file in that case this is haproxy.service and modify it a bit, original haproxy.service file on Red Hat Enterprise Linux release 8.5 (Ootpa) would look like this

Make exact copy of haproxy.service to haproxy-your-custom.service

[root@haproxy2:/usr/lib/systemd/system ]#  cp -vprf haproxy.service haproxy-customname.service
'haproxy.service' -> 'haproxy-customname.service'

[root@haproxy2:/usr/lib/systemd/system]# cp -vrpf /etc/haproxy/haproxy.cfg /etc/haproxy/haproxy_customname_prod.cfg
'/etc/haproxy/haproxy.cfg' -> '/etc/haproxy/haproxy_customname_prod.cfg'


2. Modify the new haproxy-customname.service and haproxy-custoname.cfg

a) Create hardlink copy of /usr/sbin/haproxy binary

It is a good idea to separte the haproxy executable binary for the additional systemd haproxy instance. This can be done either by copying /usr/sbin/haproxy to something like /usr/sbin/haproxy-customname-wrapper or by creating a hard link. As i'm cautious to keep the haproxy-customname-wrapper binary up2date and updated together once the haproxy rpm package / deb package is updated either with yum or apt depending on the Linux distro, hard link  use is always better.
Just for reference hardlink does keep an own copy of the binary data and occupies additional Filesystem inodes, but at the same time the first inode of the binary does point to the original binary, meaning that a package update will make the hardlink be updated up to the latest version of the file and no extra management of the hard linked haproxy-customname-wrapper is necessery.

[root@haproxy2:/usr/sbin ]# ln haproxy haproxy-custname-wrapper

[root@haproxy2:/usr/sbin ]#  ls -al haproxy-custname-wrapper
-rwxr-xr-x 2 root root 2541848 Sep  5  2021 haproxy-custname-wrapper*
root@haproxy2:/usr/sbin# ls -al haproxy
-rwxr-xr-x 2 root root 2541848 Sep  5  2021 haproxy*


b) Modify haproxy-custoname.service systemd instance

The original service file will have content like

[Unit]
Description=HAProxy Load Balancer
After=network-online.target
Wants=network-online.target

[Service]
Environment="CONFIG=/etc/haproxy/haproxy.cfg" "PIDFILE=/run/haproxy.pid"
EnvironmentFile=/etc/sysconfig/haproxy
ExecStartPre=/usr/sbin/haproxy -f $CONFIG -c -q $OPTIONS
ExecStart=/usr/sbin/haproxy -Ws -f $CONFIG -p $PIDFILE $OPTIONS
ExecReload=/usr/sbin/haproxy -f $CONFIG -c -q $OPTIONS
ExecReload=/bin/kill -USR2 $MAINPID
SuccessExitStatus=143
KillMode=mixed
Type=notify

[Install]
WantedBy=multi-user.target

 

The modified one for the customname.service should have content similar to:
 

[Unit]
Description=HAProxy Load Balancer
After=network-online.target
Wants=network-online.target

[Service]
Environment="CONFIG=/etc/haproxy/haproxy_customname_prod.cfg" "PIDFILE=/run/haproxy_customname_prod.pid"
EnvironmentFile=/etc/sysconfig/haproxy
ExecStartPre=/usr/sbin/haproxy_customname -f $CONFIG -c -q $OPTIONS
ExecStart=/usr/sbin/haproxy_customname -Ws -f $CONFIG -p $PIDFILE $OPTIONS
ExecReload=/usr/sbin/haproxy_customname -f $CONFIG -c -q $OPTIONS
ExecReload=/bin/kill -USR2 $MAINPID
SuccessExitStatus=143
KillMode=mixed
Type=notify

[Install]
WantedBy=multi-user.target

c) modify haproxy_customname_prod.cfg

Do the required config and save the file, below is minimal config sample:

[root@haproxy2:/etc/haproxy ]#  vim /etc/haproxy/haproxy_customname_prod.cfg
 

#———————————————————————
# Global settings
#———————————————————————
global
    log          127.0.0.1 local6 debug
    chroot       /var/lib/haproxy
    pidfile      /run/haproxy.pid
    stats socket /var/lib/haproxy/haproxy.sock mode 0600 level admin
    maxconn      4000
    user         haproxy
    group        haproxy
    daemon
    #debug
    #quiet

#———————————————————————
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#———————————————————————
defaults
    mode        tcp
    log         global
#    option      dontlognull
#    option      httpclose
#    option      httplog
#    option      forwardfor
    option      redispatch
    option      log-health-checks
    timeout connect 10000 # default 10 second time out if a backend is not found
    timeout client 300000
    timeout server 300000
    maxconn     60000
    retries     3
 

#———————————————————————
# round robin balancing between the various backends
#———————————————————————

frontend Frotnend_customname1
        bind 10.10.10.1:15000
        mode tcp
        option tcplog
        #log global
        log-format [%t]\ %ci:%cp\ %bi:%bp\ %b/%s:%sp\ %Tw/%Tc/%Tt\ %B\ %ts\ %ac/%fc/%bc/%sc/%rc\ %sq/%bq

       default_backend Frontend_customname1

backend Frontend_customname1
        balance roundrobin
        timeout client 350000
        timeout server 350000
        timeout connect 35000
        server backend-server1 10.10.10.50:15000 weight 1 check port 15000
        server backend-server2 10.10.10.51:15000 weight 2  check port 15000

 

3. Reload systemd to make haproxy-customname.service known to systemctl, restart the freshly created service
and check its status
 

a) Execute daemon-reload to refresh known .service files in systemd

[root@haproxy2:/etc/haproxy ]# systemctl daemon-reload
[root@haproxy2:/etc/haproxy ]#


b) Restart haproxy-customname

[root@haproxy2:/usr/lib/systemd/system ]# systemctl restart haproxy-customname
[root@haproxy2:/usr/lib/systemd/system ]#

c) Check status is active running and process is properly forked

[root@haproxy2:/usr/lib/systemd/system ]# systemctl status haproxy-customname
● haproxy-customname.service – HAProxy Load Balancer
     Loaded: loaded (/lib/systemd/system/haproxy-customname.service; disabled; vendor preset: enabled)
     Active: active (running) since Tue 2022-08-30 13:15:35 EEST; 16s ago
       Docs: man:haproxy(1)
             file:/usr/share/doc/haproxy/configuration.txt.gz
    Process: 346635 ExecStartPre=/usr/sbin/haproxy-customname-wrapper -f $CONFIG -c -q $EXTRAOPTS (code=exited, status=0/SUCCES>
   Main PID: 346637 (haproxy-customn)
      Tasks: 3 (limit: 4654)
     Memory: 14.5M
        CPU: 68ms
     CGroup: /system.slice/haproxy-customname.service
             ├─346637 /usr/sbin/haproxy-customname-wrapper -Ws -f /etc/haproxy/haproxy_customname_prod.cfg -p /run/haproxy_cust>
             └─346639 /usr/sbin/haproxy-customname-wrapper -Ws -f /etc/haproxy/haproxy_customname_prod.cfg -p /run/haproxy_cust>

Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]:    | timeouts are set to a non-zero value: 'client', 'connect', 's>
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: [NOTICE] 241/131535 (346637) : New worker #1 (346639) forked
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy webservers_http started.
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy webservers_http started.
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy https-in started.
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy https-in started.
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy webservers-https started.
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy webservers-https started.
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy stats started.
Aug 30 13:15:35 haproxy2 haproxy-customname-wrapper[346637]: Proxy stats started.

The new haproxy-customname.service processes will be visible in process list together with the normal haproxy.service spawned processes:

[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
 

Following the same steps you can create as many separate haproxy instances as you like, but you have to be cautious not to intermix the listener ports for frontends. There is always risk when you copy from the original /etc/haproxy/haproxy.cfg to /etc/haproxy/haproxy-whatever.cfg to forget to change the listen port addresses in new config. 
Also note, that you might have problems, if you exceeed the usual maximum number of ports  65535 by using a high port ranges in the listeneres and due to that your additional systemd instances might refuse to start.

If you need to create a multiple bunch of systemd separte instances and haproxy configurations you can write easily a small script in bash that does this steps automatically.
Hope this article helped someone. If so drop me a thanks email or do your appreatiation for my blog by supporting my patreon.

Cheers ! 🙂

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Posted in Hacks, Haproxy, Linux, System Administration | No Comments »

How to disable appArmor automatically installed and loaded after Linux Debian 10 to 11 Upgrade. Disable Apparmour on Deb based Linux

Friday, January 28th, 2022

check-apparmor-status-linux-howto-disable-Apparmor_on-debian-ubuntu-mint-and-other-deb-based-linux-distributions

I've upgraded recently all my machines from Debian Buster Linux 10 to Debian 11 Bullseye (if you wonder what Bullseye is) this is one of the heroes of Disneys Toy Stories which are used for a naming of General Debian Distributions.
After the upgrade most of the things worked expected, expect from some stuff like MariaDB (MySQL) and other weirdly behaving services. After some time of investigation being unable to find out what was causing the random issues observed on the machines. I finally got the strange daemon improper functioning and crashing was caused by AppArmor.

AppArmor ("Application Armor") is a Linux kernel security module that allows the system administrator to restrict programs' capabilities with per-program profiles. Profiles can allow capabilities like network access, raw socket access, and the permission to read, write, or execute files on matching paths. AppArmor supplements the traditional Unix discretionary access control (DAC) model by providing mandatory access control (MAC). It has been partially included in the mainline Linux kernel since version 2.6.36 and its development has been supported by Canonical since 2009.

The general idea of apparmor is wonderful as it could really strengthen system security, however it should be setup on install time and not setup on update time. For one more time I got convinced myself that upgrading from version to version to keep up to date with security is a hard task and often the results are too much unexpected and a better way to upgrade from General version to version any modern Linux / Unix distribution (and their forked mobile equivalents Android etc.) is to just make a copy of the most important configuration, setup the services on a freshly new installed machine be it virtual or a physical Server and rebuild the whole system from scratch, test and then run the system in production, substituting the old server general version with the new machine. 

The rest is leading to so much odd issues like this time with AppArmors causing distractions on the servers hosted applications.

But enough rent if you're unlucky and unwise enough to try to Upgrade Debian / Ubuntu 20, 21 / Mint 18, 19 etc. or whatever Deb distro from older general release to a newer One. Perhaps the best first thing to do onwards is stop and remove AppArmor (those who are hardcore enthusiasts could try to enable the failing services due to apparmor), by disabling the respective apparmor hardening profile but i did not have time to waste on stupid stuff and experiment so I preferred to completely stop it. 

To identify the upgrade oddities has to deal with apparmors service enabled security protections you should be able to find respective records inside /var/log/messages as well as in /var/log/audit/audit.log

 

# dmesg

[   64.210463] audit: type=1400 audit(1548120161.662:21): apparmor="DENIED" operation="sendmsg" info="Failed name lookup – disconnected path" error=-13 profile="/usr/sbin/mysqld" name="run/systemd/notify" pid=2527 comm="mysqld" requested_mask="w" denied_mask="w" fsuid=113 ouid=0
[  144.364055] audit: type=1400 audit(1548120241.595:22): apparmor="DENIED" operation="sendmsg" info="Failed name lookup – disconnected path" error=-13 profile="/usr/sbin/mysqld" name="run/systemd/notify" pid=2527 comm="mysqld" requested_mask="w" denied_mask="w" fsuid=113 ouid=0
[  144.465883] audit: type=1400 audit(1548120241.699:23): apparmor="DENIED" operation="sendmsg" info="Failed name lookup – disconnected path" error=-13 profile="/usr/sbin/mysqld" name="run/systemd/notify" pid=2527 comm="mysqld" requested_mask="w" denied_mask="w" fsuid=113 ouid=0
[  144.566363] audit: type=1400 audit(1548120241.799:24): apparmor="DENIED" operation="sendmsg" info="Failed name lookup – disconnected path" error=-13 profile="/usr/sbin/mysqld" name="run/systemd/notify" pid=2527 comm="mysqld" requested_mask="w" denied_mask="w" fsuid=113 ouid=0
[  144.666722] audit: type=1400 audit(1548120241.899:25): apparmor="DENIED" operation="sendmsg" info="Failed name lookup – disconnected path" error=-13 profile="/usr/sbin/mysqld" name="run/systemd/notify" pid=2527 comm="mysqld" requested_mask="w" denied_mask="w" fsuid=113 ouid=0
[  144.767069] audit: type=1400 audit(1548120241.999:26): apparmor="DENIED" operation="sendmsg" info="Failed name lookup – disconnected path" error=-13 profile="/usr/sbin/mysqld" name="run/systemd/notify" pid=2527 comm="mysqld" requested_mask="w" denied_mask="w" fsuid=113 ouid=0
[  144.867432] audit: type=1400 audit(1548120242.099:27): apparmor="DENIED" operation="sendmsg" info="Failed name lookup – disconnected path" error=-13 profile="/usr/sbin/mysqld" name="run/systemd/notify" pid=2527 comm="mysqld" requested_mask="w" denied_mask="w" fsuid=113 ouid=0


1. How to check if AppArmor is running on the system

If you have a system with enabled apparmor you should get some output like:

root@haproxy2:~# apparmor_status 
apparmor module is loaded.
5 profiles are loaded.
5 profiles are in enforce mode.
   /usr/sbin/ntpd
   lsb_release
   nvidia_modprobe
   nvidia_modprobe//kmod
   tcpdump
0 profiles are in complain mode.
1 processes have profiles defined.
1 processes are in enforce mode.
   /usr/sbin/ntpd (387) 
0 processes are in complain mode.
0 processes are unconfined but have a profile defined.


Also if you check the service you will find out that Debian's Major Release upgrade from 10 Buster to 11 BullsEye with.

# apt update -y && apt upgrade -y && apt dist-update -y
…

automatically installed apparmor and started the service, e.g.:

# systemctl status apparmor
● apparmor.service – Load AppArmor profiles
     Loaded: loaded (/lib/systemd/system/apparmor.service; enabled; vendor pres>
     Active: active (exited) since Sat 2022-01-22 23:04:58 EET; 5 days ago
       Docs: man:apparmor(7)
             https://gitlab.com/apparmor/apparmor/wikis/home/
    Process: 205 ExecStart=/lib/apparmor/apparmor.systemd reload (code=exited, >
   Main PID: 205 (code=exited, status=0/SUCCESS)
        CPU: 43ms

яну 22 23:04:58 haproxy2 apparmor.systemd[205]: Restarting AppArmor
яну 22 23:04:58 haproxy2 apparmor.systemd[205]: Reloading AppArmor profiles
яну 22 23:04:58 haproxy2 systemd[1]: Starting Load AppArmor profiles…
яну 22 23:04:58 haproxy2 systemd[1]: Finished Load AppArmor profiles.

 

# dpkg -l |grep -i apparmor
ii  apparmor                          2.13.6-10                      amd64        user-space parser utility for AppArmor
ii  libapparmor1:amd64                2.13.6-10                      amd64        changehat AppArmor library
ii  libapparmor-perl:amd64               2.13.6-10


In case AppArmor is disabled, you will get something like:

root@pcfrxenweb:~# aa-status 
apparmor module is loaded.
0 profiles are loaded.
0 profiles are in enforce mode.
0 profiles are in complain mode.
0 processes have profiles defined.
0 processes are in enforce mode.
0 processes are in complain mode.
0 processes are unconfined but have a profile defined.


2. How to disable AppArmor for particular running services processes

In my case after the upgrade of a system running a MySQL Server suddenly out of nothing after reboot the Database couldn't load up properly and if I try to restart it with the usual

root@pcfrxen: /# systemctl restart mariadb

I started getting errors like:

DBI connect failed : Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

To get an idea of what kind of profile definitions, could be enabled disabled on apparmor enabled system do:
 

root@pcfrxen:/var/log# ls -1 /etc/apparmor.d/
abstractions/
force-complain/
local/
lxc/
lxc-containers
samba/
system_tor
tunables/
usr.bin.freshclam
usr.bin.lxc-start
usr.bin.man
usr.bin.tcpdump
usr.lib.telepathy
usr.sbin.clamd
usr.sbin.cups-browsed
usr.sbin.cupsd
usr.sbin.ejabberdctl
usr.sbin.mariadbd
usr.sbin.mysqld
usr.sbin.named
usr.sbin.ntpd
usr.sbin.privoxy
usr.sbin.squid

Lets say you want to disable any protection AppArmor profile for MySQL you can do it with:

root@pcfrxen:/ #  ln -s /etc/apparmor.d/usr.sbin.mysqld /etc/apparmor.d/disable/
root@pcfrxen:/ # apparmor_parser -R /etc/apparmor.d/usr.sbin.mysqld 


To make the system know you have disabled a profile you should restart apparmor service:
 

root@pcfrxen:/ # systemctl restart apparmor.service


3. Disable completely AppArmor to save your time weird system behavior and hang bangs

In my opinion the best thing to do anyways, especially if you don't run Containerized applications, that runs only one single application / service at at time is to completely disable apparmor, otherwise you would have to manually check each of the running applications before the upgrade and make sure that apparmor did not bring havoc to some of it.
Hence my way was to simple get rid of apparmor by disable and remove the related package completely out of the system to do so:

root@pcfrxen:/ # systemctl stop apparmor
root@pcfrxen:/ # systemctl disable apparmor
root@pcfrxen:/ # apt-get remove -y apparmor

Once  disabled to make the system completely load out anything loaded related to apparmor loaded into system memory, you should do machine reboot.

root@pcfrxen:/ # shutdown -r now

Hopefully if you run into same issue after removal of apparmor most of the things should be working fine after the upgrade. Anyways I had to go through each and every app everywhere and make sure it is working as expected. The major release upgrade has also automatically enabled me some of the already disable services, thus if you have upgraded like me I would advice you do a close check on every enabled / running service everywhere:

root@pcfrxen:/# systemctl list-unit-files|grep -i enabled

Beware of AppArmor  !!! 🙂

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Install and enable Sysstats IO / DIsk / CPU / Network monitoring console suite on Redhat 8.3, Few sar useful command examples

Tuesday, September 28th, 2021

linux-sysstat-monitoring-logo

 

Why to monitoring CPU, Memory, Hard Disk, Network usage etc. with sysstats tools?
 

Using system monitoring tools such as Zabbix, Nagios Monit is a good approach, however sometimes due to zabbix server interruptions you might not be able to track certain aspects of system performance on time. Thus it is always a good idea to 
Gain more insights on system peroformance from command line. Of course there is cmd tools such as iostat and top, free, vnstat that provides plenty of useful info on system performance issues or bottlenecks. However from my experience to have a better historical data that is systimized and all the time accessible from console it is a great thing to have sysstat package at place. Since many years mostly on every server I administer, I've been using sysstats to monitor what is going on servers over a short time frames and I'm quite happy with it. In current company we're using Redhats and CentOS-es and I had to install sysstats on Redhat 8.3. I've earlier done it multiple times on Debian / Ubuntu Linux and while I've faced on some .deb distributions complications of making sysstat collect statistics I've come with an article on Howto fix sysstat Cannot open /var/log/sysstat/sa no such file or directory” on Debian / Ubuntu Linux
 

Sysstat contains the following tools related to collecting I/O and CPU statistics:
iostat
Displays an overview of CPU utilization, along with I/O statistics for one or more disk drives.
mpstat
Displays more in-depth CPU statistics.
Sysstat also contains tools that collect system resource utilization data and create daily reports based on that data. These tools are:
sadc
Known as the system activity data collector, sadc collects system resource utilization information and writes it to a file.
sar
Producing reports from the files created by sadc, sar reports can be generated interactively or written to a file for more intensive analysis.

My experience with CentOS 7 and Fedora to install sysstat it was pretty straight forward, I just had to install it via yum install sysstat wait for some time and use sar (System Activity Reporter) tool to report collected system activity info stats over time.
Unfortunately it seems on RedHat 8.3 as well as on CentOS 8.XX instaling sysstats does not work out of the box.

To complete a successful installation of it on RHEL 8.3, I had to:

[root@server ~]# yum install -y sysstat


To make sysstat enabled on the system and make it run, I've enabled it in sysstat

[root@server ~]# systemctl enable sysstat


Running immediately sar command, I've faced the shitty error:


“Cannot open /var/log/sysstat/sa18:
No such file or directory. Please check if data collecting is enabled”
 

Once installed I've waited for about 5 minutes hoping, that somehow automatically sysstat would manage it but it didn't.

To solve it, I've had to create additionally file /etc/cron.d/sysstat (weirdly RPM's post install instructions does not tell it to automatically create it)

[root@server ~]# vim /etc/cron.d/sysstat

# run system activity accounting tool every 10 minutes
0 * * * * root /usr/lib64/sa/sa1 60 59 &
# generate a daily summary of process accounting at 23:53
53 23 * * * root /usr/lib64/sa/sa2 -A &

 

  • /usr/local/lib/sa1 is a shell script that we can use for scheduling cron which will create daily binary log file.
  • /usr/local/lib/sa2 is a shell script will change binary log file to human-readable form.

 

[root@server ~]# chmod 600 /etc/cron.d/sysstat

[root@server ~]# systemctl restart sysstat


In a while if sysstat is working correctly you should get produced its data history logs inside /var/log/sa

[root@server ~]# ls -al /var/log/sa 


Note that the standard sysstat history files on Debian and other modern .deb based distros such as Debian 10 (in  y.2021) is stored under /var/log/sysstat

Here is few useful uses of sysstat cmds


1. Check with sysstat machine history SWAP and RAM Memory use


To lets say check last 10 minutes SWAP memory use:

[hipo@server yum.repos.d] $ sar -W  |last -n 10
 

Linux 4.18.0-240.el8.x86_64 (server)       09/28/2021      _x86_64_        (8 CPU)

12:00:00 AM  pswpin/s pswpout/s
12:00:01 AM      0.00      0.00
12:01:01 AM      0.00      0.00
12:02:01 AM      0.00      0.00
12:03:01 AM      0.00      0.00
12:04:01 AM      0.00      0.00
12:05:01 AM      0.00      0.00
12:06:01 AM      0.00      0.00

[root@ccnrlb01 ~]# sar -r | tail -n 10
14:00:01        93008   1788832     95.06         0   1357700    725740      9.02    795168    683484        32
14:10:01        78756   1803084     95.81         0   1358780    725740      9.02    827660    652248        16
14:20:01        92844   1788996     95.07         0   1344332    725740      9.02    813912    651620        28
14:30:01        92408   1789432     95.09         0   1344612    725740      9.02    816392    649544        24
14:40:01        91740   1790100     95.12         0   1344876    725740      9.02    816948    649436        36
14:50:01        91688   1790152     95.13         0   1345144    725740      9.02    817136    649448        36
15:00:02        91544   1790296     95.14         0   1345448    725740      9.02    817472    649448        36
15:10:01        91108   1790732     95.16         0   1345724    725740      9.02    817732    649340        36
15:20:01        90844   1790996     95.17         0   1346000    725740      9.02    818016    649332        28
Average:        93473   1788367     95.03         0   1369583    725074      9.02    800965    671266        29

 

2. Check system load? Are my processes waiting too long to run on the CPU?

[root@server ~ ]# sar -q |head -n 10
Linux 4.18.0-240.el8.x86_64 (server)       09/28/2021      _x86_64_        (8 CPU)

12:00:00 AM   runq-sz  plist-sz   ldavg-1   ldavg-5  ldavg-15   blocked
12:00:01 AM         0       272      0.00      0.02      0.00         0
12:01:01 AM         1       271      0.00      0.02      0.00         0
12:02:01 AM         0       268      0.00      0.01      0.00         0
12:03:01 AM         0       268      0.00      0.00      0.00         0
12:04:01 AM         1       271      0.00      0.00      0.00         0
12:05:01 AM         1       271      0.00      0.00      0.00         0
12:06:01 AM         1       265      0.00      0.00      0.00         0


3. Show various CPU statistics per CPU use
 

On a multiprocessor, multi core server sometimes for scripting it is useful to fetch processor per use historic data, 
this can be attained with:

 

[hipo@server ~ ] $ mpstat -P ALL
Linux 4.18.0-240.el8.x86_64 (server)       09/28/2021      _x86_64_        (8 CPU)

06:08:38 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
06:08:38 PM  all    0.17    0.02    0.25    0.00    0.05    0.02    0.00    0.00    0.00   99.49
06:08:38 PM    0    0.22    0.02    0.28    0.00    0.06    0.03    0.00    0.00    0.00   99.39
06:08:38 PM    1    0.28    0.02    0.36    0.00    0.08    0.02    0.00    0.00    0.00   99.23
06:08:38 PM    2    0.27    0.02    0.31    0.00    0.06    0.01    0.00    0.00    0.00   99.33
06:08:38 PM    3    0.15    0.02    0.22    0.00    0.03    0.01    0.00    0.00    0.00   99.57
06:08:38 PM    4    0.13    0.02    0.20    0.01    0.03    0.01    0.00    0.00    0.00   99.60
06:08:38 PM    5    0.14    0.02    0.27    0.00    0.04    0.06    0.01    0.00    0.00   99.47
06:08:38 PM    6    0.10    0.02    0.17    0.00    0.04    0.02    0.00    0.00    0.00   99.65
06:08:38 PM    7    0.09    0.02    0.15    0.00    0.02    0.01    0.00    0.00    0.00   99.70


 

sar-sysstat-cpu-statistics-screenshot

Monitor processes and threads currently being managed by the Linux kernel.

[hipo@server ~ ] $ pidstat

pidstat-various-random-process-statistics

[hipo@server ~ ] $ pidstat -d 2


pidstat-show-processes-with-most-io-activities-linux-screenshot

This report tells us that there is few processes with heave I/O use Filesystem system journalling daemon jbd2, apache, mysqld and supervise, in 3rd column you see their respective PID IDs.

To show threads used inside a process (like if you press SHIFT + H) inside Linux top command:

[hipo@server ~ ] $ pidstat -t -p 10765 1 3

Linux 4.19.0-14-amd64 (server)     28.09.2021     _x86_64_    (10 CPU)

21:41:22      UID      TGID       TID    %usr %system  %guest   %wait    %CPU   CPU  Command
21:41:23      108     10765         –    1,98    0,99    0,00    0,00    2,97     1  mysqld
21:41:23      108         –     10765    0,00    0,00    0,00    0,00    0,00     1  |__mysqld
21:41:23      108         –     10768    0,00    0,00    0,00    0,00    0,00     0  |__mysqld
21:41:23      108         –     10771    0,00    0,00    0,00    0,00    0,00     5  |__mysqld
21:41:23      108         –     10784    0,00    0,00    0,00    0,00    0,00     7  |__mysqld
21:41:23      108         –     10785    0,00    0,00    0,00    0,00    0,00     6  |__mysqld
21:41:23      108         –     10786    0,00    0,00    0,00    0,00    0,00     2  |__mysqld
…

10765 – is the Process ID whose threads you would like to list

With pidstat, you can further monitor processes for memory leaks with:

[hipo@server ~ ] $ pidstat -r 2

 

4. Report paging statistics for some old period

 

[root@server ~ ]# sar -B -f /var/log/sa/sa27 |head -n 10
Linux 4.18.0-240.el8.x86_64 (server)       09/27/2021      _x86_64_        (8 CPU)

15:42:26     LINUX RESTART      (8 CPU)

15:55:30     LINUX RESTART      (8 CPU)

04:00:01 PM  pgpgin/s pgpgout/s   fault/s  majflt/s  pgfree/s pgscank/s pgscand/s pgsteal/s    %vmeff
04:01:01 PM      0.00     14.47    629.17      0.00    502.53      0.00      0.00      0.00      0.00
04:02:01 PM      0.00     13.07    553.75      0.00    419.98      0.00      0.00      0.00      0.00
04:03:01 PM      0.00     11.67    548.13      0.00    411.80      0.00      0.00      0.00      0.00

 

5.  Monitor Received RX and Transmitted TX network traffic perl Network interface real time
 

To print out Received and Send traffic per network interface 4 times in a raw

sar-sysstats-network-traffic-statistics-screenshot
 

[hipo@server ~ ] $ sar -n DEV 1 4


To continusly monitor all network interfaces I/O traffic

[hipo@server ~ ] $ sar -n DEV 1


To only monitor a certain network interface lets say loopback interface (127.0.0.1) received / transmitted bytes

[hipo@server yum.repos.d] $  sar -n DEV 1 2|grep -i lo
06:29:53 PM        lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
06:29:54 PM        lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
Average:           lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00


6. Monitor block devices use
 

To check block devices use 3 times in a raw
 

[hipo@server yum.repos.d] $ sar -d 1 3


sar-sysstats-blockdevice-statistics-screenshot
 

7. Output server monitoring data in CSV database structured format


For preparing a nice graphs with Excel from CSV strucuted file format, you can dump the collected data as so:

 [root@server yum.repos.d]# sadf -d /var/log/sa/sa27 — -n DEV | grep -v lo|head -n 10
server-name-fqdn;-1;2021-09-27 13:42:26 UTC;LINUX-RESTART    (8 CPU)
# hostname;interval;timestamp;IFACE;rxpck/s;txpck/s;rxkB/s;txkB/s;rxcmp/s;txcmp/s;rxmcst/s;%ifutil
server-name-fqdn;-1;2021-09-27 13:55:30 UTC;LINUX-RESTART    (8 CPU)
# hostname;interval;timestamp;IFACE;rxpck/s;txpck/s;rxkB/s;txkB/s;rxcmp/s;txcmp/s;rxmcst/s;%ifutil
server-name-fqdn;60;2021-09-27 14:01:01 UTC;eth1;19.42;16.12;1.94;1.68;0.00;0.00;0.00;0.00
server-name-fqdn;60;2021-09-27 14:01:01 UTC;eth0;7.18;9.65;0.55;0.78;0.00;0.00;0.00;0.00
server-name-fqdn;60;2021-09-27 14:01:01 UTC;eth2;5.65;5.13;0.42;0.39;0.00;0.00;0.00;0.00
server-name-fqdn;60;2021-09-27 14:02:01 UTC;eth1;18.90;15.55;1.89;1.60;0.00;0.00;0.00;0.00
server-name-fqdn;60;2021-09-27 14:02:01 UTC;eth0;7.15;9.63;0.55;0.74;0.00;0.00;0.00;0.00
server-name-fqdn;60;2021-09-27 14:02:01 UTC;eth2;5.67;5.15;0.42;0.39;0.00;0.00;0.00;0.00
…

To graph the output data you can use Excel / LibreOffice's Excel equivalent Calc or if you need to dump a CSV sar output and generate it on the fly from a script  use gnuplot 


What we've learned?


How to install and enable on cron sysstats on Redhat and CentOS 8 Linux ? 
How to continuously monitor CPU / Disk and Network, block devices, paging use and processes and threads used by the kernel per process ?  
As well as how to export previously collected data to CSV to import to database or for later use inrder to generate graphic presentation of data.
Cheers ! 🙂

 

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Linux: How to set KVM Virtual Machine to autostart on system boot

Thursday, July 15th, 2021

linux-kvm-set-vm-to-automatically-boot-on-linux-system-boot

Recently I've written a short article on how to make auto boot OpenVZ container Virtual Machine if system gets rebooted as I had the task to do so in daily job as sysadmin.
Few days ago after some power outage in one of Frankfurt based Data Centers, some Rack tech equipment has been temporary powered of and once the electricity was up again, some Linux servers  running Kernel Based Virtualization ( KVM ) some of the virtual machines did not managed to automatically start up and we had to manually start them one by one.
To manually start each of the machines that did not start up had to do the trivial:

[root@hypervisor ~]# virsh list
 Id    Name                           State
—————————————————-
 3     VM500                   running

[root@hypervisor ~]# virsh dominfo VM500
Id:             3
Name:           VM500
UUID:           82075903-a4ce-5ec0-a3d8-9ee83d85fc75
OS Type:        hvm
State:          running
CPU(s):         2
CPU time:       247407.9s
Max memory:     2097152 KiB
Used memory:    2097152 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: selinux
Security DOI:   0
Security label: system_u:system_r:svirt_t:s0:c447,c723 (permissive)

[root@hypervisor ~]# virsh start VM_domain_Name

Of course logcally to prevent future issues in case if Linux server gets suddenly rebooted due to whatever reason, we had to configure the machines in questions to automatically boot on OS system boot.

In some rare cases if above start command does not help you might want to check what is the status of libvirtd and investigate the logs in /var/log/libvirt/ i.e. /var/log/libvirt/libvirt.log

An alternative but more complicated way to set virtual machine to automatically start on boot is by using default location for automatic VM start just like OpenXEn has its /etc/xen/auto/ dirtory from where each soft symlinked VM configuration from /etc/xen/VM_name.cfg is started in KVM Hypervisor hosts to auto boot a certain vm you have to link /etc/libvirt/qemu/VM-to-autoboot-name.xml to /etc/libvirt/qemu/autostart/VM-to-autoboot-name.xml. 

[root@hypervisor ~]# systemctl status libvirtd
● libvirtd.service – Virtualization daemon
   Loaded: loaded (/usr/lib/systemd/system/libvirtd.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2021-06-29 10:21:30 CEST; 2 weeks 2 days ago
     Docs: man:libvirtd(8)
           https://libvirt.org
 Main PID: 1809 (libvirtd)
    Tasks: 22 (limit: 32768)
   CGroup: /system.slice/libvirtd.service
           ├─1809 /usr/sbin/libvirtd
           ├─2335 /usr/sbin/dnsmasq –conf-file=/var/lib/libvirt/dnsmasq/default.conf –leasefile-ro –dhcp-script=/us…
           ├─2336 /usr/sbin/dnsmasq –conf-file=/var/lib/libvirt/dnsmasq/default.conf –leasefile-ro –dhcp-script=/us…
           ├─2386 /usr/sbin/dnsmasq –conf-file=/var/lib/libvirt/dnsmasq/Host-Only.conf –leasefile-ro –dhcp-script=/…
           └─2387 /usr/sbin/dnsmasq –conf-file=/var/lib/libvirt/dnsmasq/Host-Only.conf –leasefile-ro –dhcp-script=/…

If for some reason libvirtd is not running or disabled state you will have to enable it with:

[root@hypervisor ~]# systemctl enable libvirtd

If the virtualization is running on some RPM based distribtuion OpenSuse whatever and libvirtd is controlled via chkconfig (redhat runlevel alternative system), you will have to :

[root@hypervisor ~]# chkconfig libvirtd on

Disabling KVM Virtual Machine from auto start on server boot

[root@hypervisor ~]# virsh autostart Debian10 –disable
Domain Debian10 unmarked as autostarted

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Fix Zabbix selinux caused permission issues on CentOS 7 Linux / cannot set resource limit: [13] Permission denied error solution

Tuesday, July 6th, 2021

zabbix-selinux-logo-fix-zabbix-permission-issues-when-running-on-ceontos-linux-change-selinux-to-permissive-howto.

If you have to install Zabbix client that has to communicate towards Zabbix server via a Zabbix Proxy you might be unpleasently surprised that it cannot cannot be start if the selinux mode is set to Enforcing.
Error message like on below screenshot will be displayed when starting proxy client with systemctl.

zabbix-proxy-cannot-be-started-due-to-selinux-permissions

In the zabbix logs you will see error  messages such as:
 

"cannot set resource limit: [13] Permission denied, CentOS 7"

 

29085:20160730:062959.263 Starting Zabbix Agent [Test host]. Zabbix 3.0.4 (revision 61185).
29085:20160730:062959.263 **** Enabled features ****
29085:20160730:062959.263 IPv6 support: YES
29085:20160730:062959.263 TLS support: YES
29085:20160730:062959.263 **************************
29085:20160730:062959.263 using configuration file: /etc/zabbix/zabbix_agentd.conf
29085:20160730:062959.263 cannot set resource limit: [13] Permission denied
29085:20160730:062959.263 cannot disable core dump, exiting…

 

Next step to do is to check whether zabbix is listed in selinux's enabled modules to do so run:
 

[root@centos ~ ]# semodules -l
…
…..
vhostmd    1.1.0
virt    1.5.0
vlock    1.2.0
vmtools    1.0.0
vmware    2.7.0
vnstatd    1.1.0
vpn    1.16.0
w3c    1.1.0
watchdog    1.8.0
wdmd    1.1.0
webadm    1.2.0
webalizer    1.13.0
wine    1.11.0
wireshark    2.4.0
xen    1.13.0
xguest    1.2.0
xserver    3.9.4
zabbix    1.6.0
zarafa    1.2.0
zebra    1.13.0
zoneminder    1.0.0
zosremote    1.2.0
 

[root@centos ~ ]# sestatus
# sestatusSELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      28

To get exact zabbix IDs that needs to be added as permissive for Selinux you can use ps -eZ like so:

[root@centos ~ ]# ps -eZ |grep -i zabbix
system_u:system_r:zabbix_agent_t:s0 1149 ?     00:00:00 zabbix_agentd
system_u:system_r:zabbix_agent_t:s0 1150 ?     00:04:28 zabbix_agentd
system_u:system_r:zabbix_agent_t:s0 1151 ?     00:00:00 zabbix_agentd
system_u:system_r:zabbix_agent_t:s0 1152 ?     00:00:00 zabbix_agentd
system_u:system_r:zabbix_agent_t:s0 1153 ?     00:00:00 zabbix_agentd
system_u:system_r:zabbix_agent_t:s0 1154 ?     02:21:46 zabbix_agentd

As you can see zabbix is enabled and hence selinux enforcing mode is preventing zabbix client / server to operate and communicate normally, hence to make it work we need to change zabbix agent and zabbix proxy to permissive mode.

Setting selinux for zabbix agent and zabbix proxy to permissive mode

If you don't have them installed you might neet the setroubleshoot setools, setools-console and policycoreutils-python rpms packs (if you have them installed skip this step).

[root@centos ~ ]# yum install setroubleshoot.x86_64 setools.x86_64 setools-console.x86_64 policycoreutils-python.x86_64

Then to add zabbix service to become permissive either run

[root@centos ~ ]# semanage permissive –add zabbix_t

[root@centos ~ ]# semanage permissive -a zabbix_agent_t


In some cases you might also need in case if just adding the permissive for zabbix_agent_t try also :

setsebool -P zabbix_can_network=1

Next try to start zabbox-proxy and zabbix-agent systemd services 

[root@centos ~ ]# systemctl start zabbix-proxy.service
…

[root@centos ~ ]# systemctl start zabbix-agent.service
…

Hopefully all should report fine with the service checking the status should show you something like:

[root@centos ~ ]# systemctl status zabbix-agent
● zabbix-agent.service – Zabbix Agent
   Loaded: loaded (/usr/lib/systemd/system/zabbix-agent.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2021-06-24 07:47:42 CEST; 1 weeks 5 days ago
 Main PID: 1149 (zabbix_agentd)
   CGroup: /system.slice/zabbix-agent.service
           ├─1149 /usr/sbin/zabbix_agentd -c /etc/zabbix/zabbix_agentd.conf
           ├─1150 /usr/sbin/zabbix_agentd: collector [idle 1 sec]
           ├─1151 /usr/sbin/zabbix_agentd: listener #1 [waiting for connection]
           ├─1152 /usr/sbin/zabbix_agentd: listener #2 [waiting for connection]
           ├─1153 /usr/sbin/zabbix_agentd: listener #3 [waiting for connection]
           └─1154 /usr/sbin/zabbix_agentd: active checks #1 [idle 1 sec]

Check the Logs finally to make sure all is fine with zabbix being allowed by selinux.

[root@centos ~ ]# grep zabbix_proxy /var/log/audit/audit.log
…

[root@centos ~ ]# tail -n 100 /var/log/zabbix/zabbix_agentd.log


If no errors are in and you receive and you can visualize the usual zabbix collected CPU / Memory / Disk etc. values you're good, Enjoy ! 🙂

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How to install / add new root certificates on Debian, Ubuntu, Mint Linux

Saturday, October 21st, 2017

add-install-new-root-ca-certificates-to-debian-ubuntu-linux-howto

How to add / Installing a root/CA Certificate on Debian, Ubuntu, Mint Linux

 


 Because of various auditing failures and other security issues, the CAcert root certificate set is slowly disappearing from the Ubuntu and Debian ‘ca-certificates’ package.

That's really tricky because if you're a system administrator or have a bunch of programmers whose needs is to install a new set of root certificates for their freshly develped Application or you have to make a corporate certificates added to debian rootca, then the good news is it is quite easy to install new certificates to deb based distributions.

 

Given a CA certificate file foo.crt, follow these steps to install it on Debian / Ubuntu:

    Create a directory for extra CA certificates in /usr/share/ca-certificates:
 

 

    debian:~# mkdir /usr/share/ca-certificates/extra-certificates

 

    Copy the CA .crt file to this directory:
 

 

    debian:~# cp foo.crt /usr/share/ca-certificates/extra-certificates/foo.crt

 

    Let Debian / Ubuntu add the .crt file's path relative to /usr/share/ca-certificates to /etc/ca-certificates.conf (the file lists certificates that you wish to use or to ignore to be installed in /etc/ssl/certs)
 

 

    debian:~# dpkg-reconfigure ca-certificates

 

In case you want to include a .pem file to the list of trustable certificates on Debian / Ubuntu, it must first be converted to a .crt file first, you can do that with:
 

 

    debian:~# openssl x509 -in foo.pem -inform PEM -out foo.crt

 


Lets say you want to add some custom Root certificate for exapmle cacert.org

 

 

 

   debian:~# mkdir /usr/local/share/ca-certificates/cacert.org
   debian:~# cd /usr/local/share/ca-certificates/cacert.org
   debian:~# mkdir /usr/local/share/ca-certificates/cacert.org
   debian:~# wget -P /usr/local/share/ca-certificates/cacert.org http://www.cacert.org/certs/root.crt http://www.cacert.org/certs/class3.crt

 

 

 

Then once again update the ca certificates bundle

   debian:~# update-ca-certificates

 

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How to Increase virtualbox Linux install machine VM .VDI hard disk size to free space on root partition – Move /usr to a new partition

Tuesday, October 10th, 2017

extend-vdi-virtual-machine-partition-with-virtualbox-howto-virtualbox-logo
 

How to Increse Hard Disk size of VirtualBox Virtual Machine .VDI file to Free Space on root Partition or Howto move /usr large partition to separate new partition?


I just wondered how to increase hard disk size of Virtualbox Virtual Machine image .VDI, because for some stupid reason I've created my initial hard disk size for Linux partition to be the default 10 Gigabytes.

The problem is the packages I need to have installed on the Virtual Machine which will be a testbed for future tests of a production website applications are taking up too much space, once installed so I'm left with no space
in /var/lib/mysql for the database import. So what can I do in that case is to simply free up disk space or Merge ROOT partition with another partition.

Since merging the partition is not a trivial job and would require me to have installable CD with the Linux distro (in my case that's Debian Linux) or have a bootable USB flash drive, I preferred second approach to problem e.g. to free up disk space on ROOT partition by creating a second partition and move the /usr folder to reside there.

Before that it is of course necessery to  have extended the .VDI file using VirtualBox, so more space than the default 10GB preconfigured are available, this is easily done on Windows OS as, VBox is provided with GUI clickable option to do it, but for who knows what reason that is not the case with Linux, so Linux users only option to increase VDI file is to manually run command part of the virtualbox package, that is not a hard task really but it requires some typing and basic knowledge on how to run commands in terminal.


To .VDI resize (extend), we first go to default location where VirtualBox stores its image .VDI files (by default as of moment of writting this article – this is ~/"VrtualBox VMs"  (or home directory of logged in user dir VirtualBox VMs), the command to use is VBoxManage

 

root@jericho:/home/hipo# cd VirtualBox VMs/
root@jericho:/home/hipo/VirtualBox VMs# ls
Debian 6  Debian 9  Windows 10
root@jericho:/home/hipo/VirtualBox VMs# cd Debian 6/
root@jericho:/home/hipo/VirtualBox VMs/Debian 6# ls
Debian 6.vbox  Debian 6.vbox-prev  Debian 6.vdi  Logs  NewVirtualDisk1.vdi  Snapshots
root@jericho:/home/hipo/VirtualBox VMs/Debian 6# VBoxManage modifyhd Debian 6.vdi –resize 20000
0%…10%…20%…30%…40%…50%…60%…70%…80%…90%…100%
root@jericho:/home/hipo/VirtualBox VMs/Debian 6#


 

Above command does resize the 10GB default created partition for Linux, where I have installed Linux which was 99% full of data, because of the many packages I installed to 20GB size, to make it bigger just use the respective size, be it 30000 (for 30GB) or 100000 (for 100GB) etc.

Even though in this example VBoxManage virtual partition resize command was done for GNU / Linux Operating System, it can be done for any other Operating as well to resize the size of the Virtual .VDI file (Virtual Machine) partition, be it Windows 7 / 8 / 10 or the rest of Free Operating systems FreeBSD / OpenBSD / BSD that are installed in a VM etc.

Next Launch the Virtual Machine with VBox Server client Program and install there Gparted (GNU Parted), as we'll need it to create a new Hard Disk Partition:

 

$ VirtualBox

 


Inside virtualmachine's in gnome-terminal / xterm etc. depending on the graphical environment used do install with apt-get:

 

debian:# apt-get install –yes gparted
…

 

debian~:# gparted


Notice that gparted has to be ran as a root superuser.

 

Run GParted and create new EXT3 filesystem that is 10GB (the size of the new created partition).

If you have installed Debian to place all partitions under / (root directory /dev/sda1) then the fresh new partition to create should be
/dev/sda3, anyways just look closely in EXT3 and in your case if the partiition is named differently create according to proper partition /dev/ naming.

I'll not run into details on how to create the partition with GParted as the program interface is very self-explanatory, the only thing is to apply the update to create partition and the ext3 filesystem, that's being done
with a green tick:

gparted-create-ext3-partition-howto-linux

Next step is to check with fdisk whether, we have ext3 properly created  filesystem as we've done already with GPARTED:

Once we have the partition created with EXT3 filesystem, we're ready to move /usr temporary to other folder, I use usually /root for the move but you can create anywhere a new folder for that and move to there.

To move to /root directory run again in terminal:

 

debian:~# mv /usr /root
debian:~# mkdir /usr

 

howto-extend-root-filesystem-disk-space-linux-move-usr-folder-to-root-temporary-debian-gnu-linux

 

Note that during the move operations, your Desktop icons will become without (with broken) pictures and the default Debian background picture is to disappear, that's because the GUI environment will soon realize /usr/ libraries that're periodically reloaded in memory are missing and will be unable to reload them as it does in a cycle.

That should take a few minutes, so grab a coffee or if you're a smoker (hope not as smoking kills 🙂 ), in 5 / 10 minutes time depending on your computer / server configuration, it will be over, so we're ready to create new /usr dir and mount the  new partition:

 

debian:~# mount /dev/sda3 /usr

 

howto-extend-root-filesystem-disk-space-linux-move-usr-folder-to-root-temporary-debian-gnu-linux1

 

Now we check with mount command whether mount is fine:

 

check-if-filesystem-is-properly-mounted-linux-debian-screenshot


Now  /dev/sda3 is mounted under /usr  and we have to move back /root/usr directory content back to the newly mounted /usr so we run command:
 

debian:~#  mv /root/usr/* /usr/*


Finally we need to create proper records for the new partition inside /etc/fstab (fstab –FileSystem Tab file – the file which describes instructs the Linux OS what partition to boot where, what)

HOW TO CHECK LINUX UUID FOR A PARTITION??

Before adding anything to /etc/fstab you need to check the UUID of /dev/sda3 (or whatever the partition is called), without proper UUID, the system might fail to boot.
So here is how to check the UUID we'll need for config:
 

hipo@debian:~$ /sbin/blkid /dev/sda3
/dev/sda3: UUID="2273db4b-3069-4f78-90fc-e7483c0305bd" SEC_TYPE="ext2" TYPE="ext3"

hipo@debian:~$ ls -al /dev/disk/by-uuid/
total 0
drwxr-xr-x 2 root root 100 Oct  6 05:16 .
drwxr-xr-x 6 root root 120 Oct  6 05:16 ..
lrwxrwxrwx 1 root root  10 Oct  6 05:16 2273db4b-3069-4f78-90fc-e7483c0305bd -> ../../sda3
lrwxrwxrwx 1 root root  10 Oct  6 05:16 b98d92cd-41aa-4e18-a474-9b8df445dbe5 -> ../../sda1
lrwxrwxrwx 1 root root  10 Oct  6 05:16 f27f7448-f200-4983-b54f-b9e5206f77ac -> ../../sda5

As you can see our /dev/sda3 UUID is 2273db4b-3069-4f78-90fc-e7483c0305bd

Further on lets view and edit /etc/fstab you can also download a copy of my Virtual Machine fstab here

 

debian:~# cat /etc/fstab

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# / was on /dev/sda1 during installation
UUID=b98d92cd-41aa-4e18-a474-9b8df445dbe5 /               ext3    errors=remount-ro 0       1
# swap was on /dev/sda5 during installation
UUID=f27f7448-f200-4983-b54f-b9e5206f77ac none            swap    sw              0       0
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto     0       0
/dev/scd1       /media/cdrom1   udf,iso9660 user,noauto     0       0


We need to add following line to  /etc/fstab:
 

UUID=2273db4b-3069-4f78-90fc-e7483c0305bd    /usr        ext3 error=remount-ro    0    1

 


Open the file with your favourite text editor (gedit / nano / pico / vim / joe) etc.

debian:~# vim /etc/fstab

 

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# / was on /dev/sda1 during installation
UUID=b98d92cd-41aa-4e18-a474-9b8df445dbe5 /               ext3    errors=remount-ro 0       1
# swap was on /dev/sda5 during installation
UUID=f27f7448-f200-4983-b54f-b9e5206f77ac none            swap    sw              0       0
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto     0       0
/dev/scd1       /media/cdrom1   udf,iso9660 user,noauto     0       0
UUID=2273db4b-3069-4f78-90fc-e7483c0305bd     /usr        ext3 error=remount-ro    0    1    

Basicly it should be possible to add (for historic reasons) also instead of UUID=2273db4b-3069-4f78-90fc-e7483c0305bd  /dev/sda3
So it looks like so but, the better practice is to use UUID line given.

Well that's all folks now /usr directory will contain all your heavy root partition (disk filling) libraries and files, so you can happily use /var/lib/mysql or /var/lib/postgresql /var/www to store your web application files and import your databases.

Big thanks to Ubuntu Forums article – How do I increase the hard disk size of the Virtual Machine article for inspiring this post.

Hope that helps anyone and thanks and other comments are always welcome ! 🙂

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Tools to scan a Linux / Unix Web server for Malware and Rootkits / Lynis and ISPProtect – clean Joomla / WordPress and other CMS for malware and malicious scripts and trojan codes

Monday, March 14th, 2016

Linux-BSD-Unix-Rootkit-Malware-XSS-Injection-spammer-scripts-clean-howto-manual

If you have been hacked or have been suspicious that someone has broken up in some of the shared web hosting servers you happent o manage you already probably have tried the server with rkhuter, chroot and unhide tools which gives a general guidance where a server has been compromised

However with the evolution of hacking tools out there and the boom of Web security XSS / CSS / Database injections and PHP scripts vulnerability catching an intruder especially spammers has been becoming more and more hard to achieve.

Just lately a mail server of mine's load avarage increased about 10 times, and the CPU's and HDD I/O load jump over the sky.
I started evaluating the situation to find out what exactly went wrong with the machine, starting with a hardware analysis tools and a physical check up whether all was fine with the hardware Disks / Ram etc. just to find out the machine's hardware was working perfect.
I've also thoroughfully investigated on Logs of Apache, MySQL, TinyProxy and Tor server and bind DNS and DJBDns  which were happily living there for quite some time but didn't found anything strange.

Not on a last place I investigated TOP processes (with top command) and iostat  and realized the CPU high burst lays in exessive Input / Output of Hard Drive. Checking the Qmail Mail server logs and the queue with qmail-qstat was a real surprise for me as on the queue there were about 9800 emails hanging unsent, most of which were obviously a spam, so I realized someone was heavily spamming through the server and started more thoroughfully investigating ending up to a WordPress Blog temp folder (writtable by all system users) which was existing under a Joomla directory infrastructure, so I guess someone got hacked through the Joomla and uploaded the malicious php spammer script to the WordPress blog. I've instantly stopped and first chmod 000 to stop being execuded and after examing deleted view73.php, javascript92.php and index8239.php which were full of PHP values with binary encoded values and one was full of encoded strings which after being decoding were actually the recepient's spammed emails.
BTW, the view*.php javascript*.php and index*.php files were owned by www-data (the user with which Apache was owned), so obviously someone got hacked through some vulnerable joomla or wordpress script (as joomla there was quite obscure version 1.5 – where currently Joomla is at version branch 3.5), hence my guess is the spamming script was uploaded through Joomla XSS vulnerability).

As I was unsure wheteher the scripts were not also mirrored under other subdirectories of Joomla or WP Blog I had to scan further to check whether there are no other scripts infected with malware or trojan spammer codes, webshells, rootkits etc.
And after some investigation, I've actually caught the 3 scripts being mirrored under other webside folders with other numbering on filename view34.php javascript72.php, index8123.php  etc..

I've used 2 tools to scan and catch malware the trojan scripts and make sure no common rootkit is installed on the server.

1. Lynis (to check for rootkits)
2. ISPProtect (Proprietary but superb Website malware scanner with a free trial)

1. Lynis – Universal security auditing tool and rootkit scanner

Lynis is actually the well known rkhunter, I've used earlier to check servers BSD and Linux servers for rootkits.
To have up-to-date version of Lynis, I've installed it from source:
 

cd /tmp
wget https://cisofy.com/files/lynis-2.1.1.tar.gz
tar xvfz lynis-2.1.1.tar.gz
mv lynis /usr/local/
ln -s /usr/local/lynis/lynis /usr/local/bin/lynis

 


Then to scan the server for rootkits, first I had to update its malware definition database with:
 

lynis update info


Then to actually scan the system:
 

lynis audit system


Plenty of things will be scanned but you will be asked on a multiple times whether you would like to conduct different kind fo system services and log files, loadable kernel module rootkits and  common places to check for installed rootkits or server placed backdoors. That's pretty annoying as you will have to press Enter on a multiple times.

lynis-asking-to-scan-for-rootkits-backdoors-and-malware-your-linux-freebsd-netbsd-unix-server

Once scan is over you will get a System Scan Summary like in below screenshot:

lynis-scanned-server-for-rootkit-summer-results-linux-check-for-backdoors-tool

Lynis suggests also a very good things that might be tampered to make the system more secure, so using some of its output when I have time I'll work out on hardening all servers.

To prevent further incidents and keep an eye on servers I've deployed Lynis scan via cron job once a month on all servers, I've placed under a root cronjob on every first dae of month in following command:

 

 

server:~# crontab -u root -e
0 3 1 * * /usr/local/bin/lynis –quick 2>&1 | mail -s "lynis output of my server" admin-mail@my-domain.com)

 

2. ISPProtect – Website malware scanner

ISPProtect is a malware scanner for web servers, I've used it to scan all installed  CMS systems like WordPress, Joomla, Drupal etc.
ISPProtect is great for PHP / Pyhon / Perl and other CMS based frameworks.
ISPProtect contains 3 scanning engines: a signature based malware scanner, a heuristic malware scanner, and a scanner to show the installation directories of outdated CMS systems.
Unfortunately it is not free software, but I personally used the FREE TRIAL option  which can be used without registration to test it or clean an infected system.
I first webserver first locally for the infected site and then globally for all the other shared hosting websites.

As I wanted to check also rest of hosted websites, I've run ISPProtect over the all bunch of installed websites.
Pre-requirement of ISPProtect is to have a working PHP Cli and Clamav Anti-Virus installed on the server thus on RHEL (RPM) based servers make sure you have it installed if not:
 

server:~# yum -y install php

server:~# yum -y install clamav


Debian based Linux servers web hosting  admins that doesn't have php-cli installed should run:
 

server:~# apt-get install php5-cli

server:~# apt-get install clamav


Installing ISPProtect from source is with:

mkdir -p /usr/local/ispprotect
chown -R root:root /usr/local/ispprotect
chmod -R 750 /usr/local/ispprotect
cd /usr/local/ispprotect
wget http://www.ispprotect.com/download/ispp_scan.tar.gz
tar xzf ispp_scan.tar.gz
rm -f ispp_scan.tar.gz
ln -s /usr/local/ispprotect/ispp_scan /usr/local/bin/ispp_scan

 

To initiate scan with ISPProtect just invoke it:
 

server:~# /usr/local/bin/ispp_scan

 

ispprotect-scan-websites-for-malware-and-infected-with-backdoors-or-spamming-software-source-code-files

I've used it as a trial

Please enter scan key:  trial
Please enter path to scan: /var/www

You will be shown the scan progress, be patient because on a multiple shared hosting servers with few hundred of websites.
The tool will take really, really long so you might need to leave it for 1 hr or even more depending on how many source files / CSS / Javascript etc. needs to be scanned.

Once scan is completed scan and infections found logs will be stored under /usr/local/ispprotect, under separate files for different Website Engines and CMSes:

After the scan is completed, you will find the results also in the following files:
 

Malware => /usr/local/ispprotect/found_malware_20161401174626.txt
Wordpress => /usr/local/ispprotect/software_wordpress_20161401174626.txt
Joomla => /usr/local/ispprotect/software_joomla_20161401174626.txt
Drupal => /usr/local/ispprotect/software_drupal_20161401174626.txt
Mediawiki => /usr/local/ispprotect/software_mediawiki_20161401174626.txt
Contao => /usr/local/ispprotect/software_contao_20161401174626.txt
Magentocommerce => /usr/local/ispprotect/software_magentocommerce_20161401174626.txt
Woltlab Burning Board => /usr/local/ispprotect/software_woltlab_burning_board_20161401174626.txt
Cms Made Simple => /usr/local/ispprotect/software_cms_made_simple_20161401174626.txt
Phpmyadmin => /usr/local/ispprotect/software_phpmyadmin_20161401174626.txt
Typo3 => /usr/local/ispprotect/software_typo3_20161401174626.txt
Roundcube => /usr/local/ispprotect/software_roundcube_20161401174626.txt


ISPProtect is really good in results is definitely the best malicious scripts / trojan / trojan / webshell / backdoor / spammer (hacking) scripts tool available so if your company could afford it you better buy a license and settle a periodic cron job scan of all your servers, like lets say:

 

server:~# crontab -u root -e
0 3  1 * *   /usr/local/ispprotect/ispp_scan –update && /usr/local/ispprotect/ispp_scan –path=/var/www –email-results=admin-email@your-domain.com –non-interactive –scan-key=AAA-BBB-CCC-DDD


Unfortunately ispprotect is quite expensive so I guess most small and middle sized shared hosting companies will be unable to afford it.
But even for a one time run this tools worths the try and will save you an hours if not days of system investigations.
I'll be glad to hear from readers if aware of any available free software alternatives to ISPProtect. The only one I am aware is Linux Malware Detect (LMD).
I've used LMD in the past but as of time of writting this article it doesn't seems working any more so I guess the tool is currently unsupported / obsolete.

 

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How to find and Delete Duplicate files in directory on Linux server with find and fdupes command

Monday, March 16th, 2015

search-duplcate-files-linux-command-and-graphical-tools-how-to-find-duplicate-files-on-linux-mac-and-windows-os

Linux / UNIX find command is very helpful to do a lot of tasks to us admins such as Deleting empty directories to free up occupied inodes or finding and printing only empty files within a root file system within all sub-directories
There is too much of uses of find, however one that is probably rarely used known by sysadmins find command use is how to search for duplicate files on a Linux server:
 

find -not -empty -type f -printf “%s\n” | sort -rn | uniq -d | xargs -I{} -n1 find -type f -size {}c -print0 | xargs -0 md5sum | sort | uniq -w32 –all-repeated=separate

If you're curious how does duplicate files finding works, they are found by comparing file sizes and MD5 signatures, followed by a byte-by-byte comparison.

Most common application of below command is when you want to search and get rid of some old obsolete files which you forgot to delete such as old /etc/ configurations, old SQL backups and PHP / Java / Python programming code files etc.

If you have to do a regular duplicate file find on multiple servers Linux servers perhaps you should install and use  fdupes command.
On Debian Linux to install it:

root@pcfreak:/# apt-cache show fdupes|grep -i descr -A 4
Description: identifies duplicate files within given directories
 FDupes uses md5sums and then a byte by byte comparison to find
 duplicate files within a set of directories. It has several useful
 options including recursion.
Homepage: http://code.google.com/p/fdupes/

 

root@www.pc-freak.net:/# apt-get install –yes fdupes

To search for duplicate files with fdupes in lets /etc/ just run fdupes without arguments:

 

root@pcfreak:/# fdupes /etc/
/etc/magic
/etc/magic.mime

/etc/odbc.ini
/etc/.pwd.lock
/etc/environment
/etc/odbcinst.ini

/etc/shadow-
/etc/shadow


If you want to look up for all duplicate files within root directory:
 

root@pcfreak:/# fdupes -r /etc/
Building file list /
…

 

You can also find duplicate files for multiple directories by just passing all directories as arguments to fdupes

 

root@pcfreak:/# fdupes -r /etc/ /usr/ /root /disk /nfs_mount /nas
…


The -r argument (makes a recursive subdirectory search for duplicates), if you want to also see what is the size of duplicate files found add -S option

 

fdupes -r -S /etc/ /usr/ /root /disk /nfs_mount /nas

 


If you want to delete all duplicate files within lets say /etc/

 

root@pcfreak:/# fdupes -d /etc/
…

fdupes is also available and installable also on RPM based Linux distros Fedora / RHEL / CentOS etc., install on CentOS with:
 

[root@centos~ ]# yum -y install fdupes


There is also a port available for those who want to run it on FreeBSD on BSD install it from ports:

 

freebsd# cd /usr/ports/sysutils/fdupes
freebsd# make install clean


If you have a GUI environment installed on the server and you don't want to bother with command line to search for all duplicate files under main filesystem and other lint (junk) files take a look at FSlint

FSlint-2.02-search-for-duplicate-and-lint-files-linux-gui-tool

If you're looking for a GUI cross platform duplicate file finder tool that runs on all major used Operating Systems Mac OS X / Windows / Linux take a look at dupeGuru

 

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Posted in Curious Facts, Linux, Monitoring, System Administration, Various | 1 Comment »

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