Archive for the ‘System Administration’ Category

How to start / Stop and Analyze system services and improve Linux system boot time performance

Friday, July 5th, 2019

systemd-components-systemd-utilities-targets-cores-libraries
This post is going to be a very short one and to walk through shortly to System V basic start / stop remove service old way and the new ways introduced over the last 10 years or so with the introduction of systemd on mass base across Linux distributions.
Finally I'll give you few hints on how to check (analyze) the boot time performance on a modern GNU / Linux system that is using systemd enabled services.
 

1. System V and the old days few classic used ways to stop / start / restart services (runlevels and common wrapper scripts)

 

The old fashioned days when Linux was using SystemV / e.g. no SystemD used way was to just go through all the running services with following the run script logic inside the runlevel the system was booting, e.g. to check runlevel and then potimize each and every run script via the respective location of the bash service init scripts:

 

root@noah:/home/hipo# /sbin/runlevel 
N 5

 

Or on some RPM based distros like Fedora / RHEL / SUSE Enterprise Linux to use chkconfig command, e.g. list services:

~]# chkconfig –list

etworkManager  0:off   1:off   2:on    3:on    4:on    5:on    6:off
abrtd           0:off   1:off   2:off   3:on    4:off   5:on    6:off
acpid           0:off   1:off   2:on    3:on    4:on    5:on    6:off
anamon          0:off   1:off   2:off   3:off   4:off   5:off   6:off
atd             0:off   1:off   2:off   3:on    4:on    5:on    6:off
auditd          0:off   1:off   2:on    3:on    4:on    5:on    6:off
avahi-daemon    0:off   1:off   2:off   3:on    4:on    5:on    6:off

And to start stop the service into (default runlevel) or respective runlevel:

 

~]#  chkconfig httpd on

~]# chkconfig –list httpd
httpd            0:off   1:off   2:on    3:on    4:on    5:on    6:off

 

 

~]# chkconfig service_name on –level runlevels

 


Debian / Ubuntu and other .deb based distributions with System V (which executes scripts without single order but one by one) are not having natively chkconfig but instead are famous for update-rc.d init script wrapper, here is few basic use  of it:

update-rc.d <service> defaults
update-rc.d <service> start 20 3 4 5
update-rc.d -f <service>  remove

Here defaults means default set boot runtime for system and numbers are just whether service is started or stopped for respective runlevels. To check what is your default one simply run /sbin/runlevel

Other useful tool to stop / start services and analyze what service is running and which not in real time (but without modifying boot time set for a service) – more universal nowadays is to use the service command.

root@noah:/home/hipo# service –status-all
 [ + ]  acpid
 [ – ]  alsa-utils
 [ – ]  anacron
 [ + ]  apache-htcacheclean
 [ – ]  apache2
 [ + ]  atd
 [ + ]  aumix

root@noah:/home/hipo# service cron restart/usr/sbin/service command is just a simple wrapper bash shell script that takes care about start / stop etc. operations of scripts found under /etc/init.d

For those who don't want to tamper with too much typing and manual configuration there is an all distribution system V compatible ncurses interface text itnerface sysv-rc-conf which could make your life easier on configuring services on non-systemd (old) Linux-es.

To install on Debian distros:

debian:~# apt-get install sysv-rc-conf

debian:~# sysv-rc-conf


SysV RC Conf desktop on GNU Linux using sysv-rc-conf systemV and systemd
 

2. SystemD basic use Start / stop check service and a little bit of information
for the novice

As most Linux kernel based distributions except some like Slackware and few others see the full list of Linux distributions without systemd (and aha yes slackw. users loves rc.local so much – we all do 🙂  migrated and are nowadays using actively SystemD, to start / stop analyze running system runnig services / processes

systemctl – Control the systemd system and service manager

To check whether a service is enabled

systemctl is-active application.service

To check whether a unit is in a failed state

systemctl is-failed application.service

To get a status of running application via systemctl messaging

# systemctl status sshd
● ssh.service – OpenBSD Secure Shell server Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled) Active: active (running) since Sat 2019-07-06 20:01:02 EEST; 2h 3min ago Main PID: 1335 (sshd) Tasks: 1 (limit: 4915) CGroup: /system.slice/ssh.service └─1335 /usr/sbin/sshd -D юли 06 20:01:00 noah systemd[1]: Starting OpenBSD Secure Shell server… юли 06 20:01:02 noah sshd[1335]: Server listening on 0.0.0.0 port 22. юли 06 20:01:02 noah sshd[1335]: Server listening on :: port 22. юли 06 20:01:02 noah systemd[1]: Started OpenBSD Secure Shell server.

To enable / disable application with systemctl systemctl enable application.service

systemctl disable application.service

To stop / start given application systemcl stop sshd

systemctl stop tor

To reload running application

systemctl reload sshd

Some applications does not have the right functionality in systemd script to reload configuration without fully restarting the app if this is the case use systemctl reload-or-restart application.service

systemctl list-unit-files

Then to view the content of a single service unit file:

:~# systemctl cat apache2.service
# /lib/systemd/system/apache2.service
[Unit]
Description=The Apache HTTP Server
After=network.target remote-fs.target nss-lookup.target

[Service]
Type=forking
Environment=APACHE_STARTED_BY_SYSTEMD=true
ExecStart=/usr/sbin/apachectl start
ExecStop=/usr/sbin/apachectl stop
ExecReload=/usr/sbin/apachectl graceful
PrivateTmp=true
Restart=on-abort

[Install]
WantedBy=multi-user.target


converting-traditional-init-scripts-to-systemd-graphical-diagram

systemd's advancement over normal SystemV services it is able to track and show dependencies
of a single run service for proper operation on other services

:~# systemctl list-dependencies sshd.service

 


● ├─system.slice
● └─sysinit.target
●   ├─dev-hugepages.mount
●   ├─dev-mqueue.mount
●   ├─keyboard-setup.service
●   ├─kmod-static-nodes.service
●   ├─proc-sys-fs-binfmt_misc.automount
●   ├─sys-fs-fuse-connections.mount
●   ├─sys-kernel-config.mount
●   ├─sys-kernel-debug.mount
●   ├─systemd-ask-password-console.path
●   ├─systemd-binfmt.service
….

.

 

You can also mask / unmask service e.g. make it temporary unavailable via systemd with

sudo systemctl mask nginx.service

it will then appear as masked if you do list-unit-files

If you want to change something on a systemd unit file this is done with

systemctl edit –full nginx.service

In case if some modificatgion was done to systemd service files e.g. lets say to
/etc/systemd/system/apache2.service or even you've made a Linux system Upgrade recently
that added extra systemd service config files it will be necessery to reload all files
present in /etc/systemd/system/* with:

systemctl daemon-reload


Systemd has a target states which are pretty similar to the runlevel concept (e.g. runlevel 5 means graphical etc.), for example to check the default target for a system:

One very helpful feature is to restart systemd but it seems this is not well documented as of now and though this might work after some system package upgrade roll-outs it is always better to reboot the system, but you can give it a try if restart can't be done due to application criticallity.

To restart systemd and its spawned subprocesses do:
 

systemctl daemon-reexec

 

root@noah:/home/hipo# systemctl get-default
graphical.target


 to check all targets possible targets

root@noah:/home/hipo# systemctl list-unit-files –type=target
UNIT FILE                 STATE   
basic.target              static  
bluetooth.target          static  
busnames.target           static  
cryptsetup-pre.target     static  
cryptsetup.target         static  
ctrl-alt-del.target       disabled
default.target            static  
emergency.target          static  
exit.target               disabled
final.target              static  
getty.target              static  
graphical.target          static  

you can put the system in Single user mode if you like without running the good old well known command:

/sbin/init 1 

command with

systemctl rescue

You can even shutdown / poweroff / reboot system via systemctl (though I never did that and I don't recommend) 🙂
To do so use:

systemctl halt
systemctl poweroff
systemctl reboot


For the lazy ones that don't want to type all the time like crazy to configure and manage simple systemctl set services take a look at chkservice – an ncurses text based menu systemctl management interface

As chkservice is relatively new it is still not present in stable Stretch Debian repositories but it is in current testing Debian unstable Buster / Sid – Testing / Unstable distribution and has installable package for Ubuntu / Arch Linux and Fedora

chkservice-Linux-systemctl-ncurses-text-menu-service-management-interface-start-chkservice
Picture Source Tecmint.com

chkservice linux help screen


3. Analyzing and fix performance boot slowness issues due to a service taking long to boot


The first very useful thing is to know how long exactly all daemons / services got booted
on your GNU / Linux OS.

linux-server:~# systemd-analyze 
Startup finished in 4.135s (kernel) + 3min 47.863s (userspace) = 3min 51.998s

As you can see it reports both the kernel boot time and userspace (surrounding services
that had to boot for the system to be considered fully booted).


Once you have the system properly booted you have a console or / ssh access

root@pcfreak:/home/hipo# systemd-analyze blame
    2min 14.172s tor@default.service
    1min 40.455s docker.service
     1min 3.649s fail2ban.service
         58.806s nmbd.service
         53.992s rc-local.service
         51.458s systemd-tmpfiles-setup.service
         50.495s mariadb.service
         46.348s snort.service
         34.910s ModemManager.service
         33.748s squid.service
         32.226s ejabberd.service
         28.207s certbot.service
         28.104s networking.service
         23.639s munin-node.service
         20.917s smbd.service
         20.261s tinyproxy.service
         19.981s accounts-daemon.service
         18.501s loadcpufreq.service
         16.756s stunnel4.service
         15.575s oidentd.service
         15.376s dev-sda1.device
         15.368s courier-authdaemon.service
         15.301s sysstat.service
         15.154s gpm.service
         13.276s systemd-logind.service
         13.251s rsyslog.service
         13.240s lpd.service
         13.237s pppd-dns.service
         12.904s NetworkManager-wait-online.service
         12.540s lm-sensors.service
         12.525s watchdog.service
         12.515s inetd.service


As you can see you get a list of services time took to boot in secs and you can
further debug each of it to find out why it boots so slow (netwok / DNS / configuration isssue whatever).

On a servers it is useful to look up for some processes slowing it down like gdm.service etc.

 

Close up words rant on SystemD vs SysemV

init-and-systemd-comparison-commands-linux-booting-1

A lot could be ranted on what is better systemd or systemV. I personally hated systemd since day since I saw it being introduced first in Fedora / CentOS linuxes and a bit later in my beloved desktop used Debian Linux.
I still remember the bugs and headaches with systemd's intruduction as it is with all new the early adoption of technology makes a lot of pain in the ass.
Eventually systemd has become a standard and with my employment as a contractor through Itelligence GmBH for SAP AG I now am forced to work with systemd daily on SLES 12 based Linuces and I was forced to get used to it. 
But still there is my personal preference to SystemV even though the critics of slow boot etc.but for managing a multitude of Linux preinstalled servers like Virtual Machines and trying to standardize a Data Center with Tens of Thousands of Linuxes running on different Hypervisors VMWare / OpenXen + physical hosts etc. systemd brings a bit of more standardization that makes it a winner.

Check the count and monitor of established / time_wait TCP, UDP connections on Linux and Windows with netstat command

Wednesday, February 6th, 2019

netstat-windows-linux-commands-to-better-understand-your-server-type-of-networrk-tcp-udp-connections

For me as a GNU / Linux sysadmin it is intuitive to check on a server the number of established connections / connections in time_wait state and so on .

I will not explain why this is necessery as every system administrator out there who had a performance or network issues due to server / applications connection overload or have been a target of Denial of Service (DoS)
or Distributed Denial of Service attacks (DDoS)  
is well aware that a number of connections in different states such as SYN_ACK /  TIME_WAIT or ESTABLISHED state could be very nasty thing and could cause a productive application or Infrastructure service to be downed for some time causing from thousands of Euros to even millions to some bussinesses as well as some amount of data loss …

To prevent this therefore sysadmins should always take a look periodically on the Connection states on the adminned server (and in this number I say not only sys admins but DevOps guys who are deploying micro-services for a customer in the Cloud – yes I believe Richard Stallman is right here they're clouding your minds :).

Even though cloud services could provide a very high amount of Hardware (CPU / Memory / Storage) resources, often for custom applications migrating the application in the Cloud does not solve it's design faults or even problems on a purely classical system administration level.

 

1. Get a statistic for FIN_WAIT1, FOREIGN, SYNC_RECV, LAST_ACK, TIME_WAIT, LISTEN and ESTABLISHED  Connections on GNU / Linux

 

On GNU / Linux and other Linux like UNIXes the way to do it is to grep out the TCP / UDP connection type you need via netstat a very useful cmd in that case is:

 

root@pcfreak:~# netstat -nat | awk '{print $6}' | sort | uniq -c | sort -n
      1 established)
      1 FIN_WAIT1
      1 Foreign
      1 SYN_RECV
      3 LAST_ACK
      4 FIN_WAIT2
      8 TIME_WAIT
     45 LISTEN
    147 ESTABLISHED

 

2. Netstat 1 liner to Get only established and time_wait connections state 

 

Other ways to check only TCP ESTABLISHED connections on Linux I use frequently are:

 

root@pcfreak:~# netstat -etna|grep -i establi|wc -l
145

 

netstat-connection-types-statistics-linux-established-time-wait-check-count

Or to get whole list of connections including the ones who are about to be esatablished in FIN_WAIT2, TIME_WAIT, SYN_RECV state:

 

root@pcfreak:~# netstat -tupen |wc -l
164

 

3. Other Linux useful one liner commands to track your connection types
 

netstat -n -p | grep SYN_REC | sort -u

List out the all IP addresses involved instead of just count.

netstat -n -p | grep SYN_REC | awk '{print $5}' | awk -F: '{print $1}'

 

List all the unique IP addresses of the node that are sending SYN_REC connection status.

netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

 

Use netstat command to calculate and count the number of connections each IP address makes to the server.

netstat -anp |grep 'tcp\|udp' | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

 

List count of number of connections the IPs are connected to the server using TCP or UDP protocol.

netstat -ntu | grep ESTAB | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -nr

 

Check on ESTABLISHED connections instead of all connections, and displays the connections count for each IP.

 

netstat -plan|grep :80|awk {'print $5'}|cut -d: -f 1|sort|uniq -c|sort -nk 1

 

Show and list IP address and its connection count that connect to port 80 on the server. Port 80 is used mainly by HTTP web page request.

Examples are taken from this nice blog post

 

4. Check the count of esatblished connections on M$ Windows

 

As I'm forced to optimize a couple of Microsoft Windows DNS servers which are really slow to resolve the
The logical question for me was how the Established and TIME_WAIT state connections then could be checked on Windows OS, after a quick investigation online I've come up with this:

 

C:\Users\admin> netstat -nao | find /i "estab" /c
78

 

netstat-check-number-of-established-ports-connections-windows
 

 

C:\Users\admin> netsatt -nao | find /i "time_wait" /c
333

 

 

If you're used to Linux watch command, then to do same on Windows OS (e.g. check the output of netstat) command every second
and print output use:

 

netstat –an 1 | find “3334”

 

Below commands will show stats for services listening on TCP port 3334

To find out which process on system sends packets to remote destination:

 

netstat –ano 1 | find “Dest_IP_Addr”

 

The -o parameter outputs the process ID (PID) responsible for the connection.
then if you need further you can find the respective process name with tasklist< cmd.
Another handy Windows netstat option is -b which will show EXE file running as long as
the related used DLL Libraries which use TCP / UDP .

Other useful netsatat Win example is to grep for a port and show all established connections for it with:

 

netstat –an 1 | find “8080” | find “ESTABLISHED”

 

5. Closure


Hopefully this article will give you some idea on what is eating your bandwidth connections or overloading your GNU / Linux – Windows systems. And will point you to the next in line logical thing to do optimization / tuning
settings to be made on your system for example if Linux with sysctl – see my previous relater article here

I'll be intested to hear from sysadm colleagoes for other useful ways to track connections perhaps with something like ss tool (a utility to investigate sockets).
Also any optimization hints that would cause servers less downtime and improve network / performance thouroughput is mostly welcome.

 

Export / Import PuTTY Tunnels SSH Sessions from one to another Windows machine howto

Thursday, January 31st, 2019

Putty-copy-ssh-tunnels-howto-from-one-to-another-windows-machine-3

As I've started on job position – Linux Architect in last November 2018 in Itelligence AG as a contractor (External Service) – a great German company who hires the best IT specialists out there and offers a flexible time schedules for emploees doing various very cool IT advanced operations and Strategic advancement of SAP's Cloud used Technology and Services improvements for SAP SE – SAP S4HANA and HEC (HANA Enterprise Cloud) and been given for work hardware a shiny Lenovo Thinkpad 500 Laptop with Windows 10 OS (SAP pre-installed), I needed to make some SSH Tunnels to machines to (Hop Station / Jump hosts) for that purpose, after some experimenting with MobaXterm Free (Personal Edition 11.0) and the presumable limitations of tunnels of the free client as well as my laziness to add the multiple ssh tunnels to different ssh / rdp / vnc etc. servers, finally I decided to just copy all the tunnels from a colleague who runs Putty and again use the good old Putty – old school Winblows SSH Terminal Client but just for creating the SSH tunnels and for rest use MobaXterm, just like in old times while still employe in Hewlett Packard. For that reason to copy the Tunnels from my dear German Colleague Henry Beck (A good herated collegue who works in field of Storage dealing with NetApps / filer Clusters QNap etc.).

Till that moment I had no idea how copying a saved SSH Tunnels definition is possible, I did a quick research just to find out this is done not with Putty Interface itself but, insetead through dumping Windows Putty Stored Registry records into a File, then transfer to the PC where Tunnels needs to be imported and then again (either double click the registry file) to load it, into registry or use Windows registry editor command line interface reg, here is how:
 

1. Export

 

Run cmd.exe (note below command) 

requires elevated Run as Administrator prompt:

Only sessions:

regedit /e "%USERPROFILE%\Desktop\putty-sessions.reg" HKEY_CURRENT_USER\Software\SimonTatham\PuTTY\Sessions

All settings:

regedit /e "%USERPROFILE%\Desktop\putty.reg" HKEY_CURRENT_USER\Software\SimonTatham

Powershell:

If you have powershell installed on machine, to dump

Only sessions:


 

reg export HKCU\Software\SimonTatham\PuTTY\Sessions ([Environment]::GetFolderPath("Desktop") + "\putty-sessions.reg")

All settings:

reg export HKCU\Software\SimonTatham ([Environment]::GetFolderPath("Desktop") + "\putty.reg")


2. Import

Double-click on the 

*.reg

 file and accept the import.

 

Alternative ways:

 

cmd.exe

require elevated command prompt:

regedit /i putty-sessions.reg regedit /i putty.reg

PowerShell:

reg import putty-sessions.reg reg import putty.reg



Below are some things to consider:

Note !do not replace 

SimonTatham

 with your username.

 

Note !: It will create a 

reg

 file on the Desktop of the current user (for a different location modify path)

 

Note !: It will not export your related (old system stored) SSH keys.

What to expect next?

Putty-Tunnels-SSH-Sessions-screenshot-Windows

The result is in Putty you will have the Tunnel sessions loadable when you launch (Portable or installed) Putty version.
Press Load button over the required saved Tunnels list and there you go under

 

Connection SSH -> Tunnels 

 

you will see all the copied tunnels.

Enjoy!

Automatic network restart and reboot Linux server script if ping timeout to gateway is not responding as a way to reduce connectivity downtimes

Monday, December 10th, 2018

automatic-server-network-restart-and-reboot-script-if-connection-to-server-gateway-inavailable-tux-penguing-ascii-art-bin-bash

Inability of server to come back online server automaticallyafter electricity / network outage

These days my home server  is experiencing a lot of issues due to Electricity Power Outages, a construction dig operations to fix / change waterpipe tubes near my home are in action and perhaps the power cables got ruptered by the digger machine.
The effect of all this was that my server networking accessability was affected and as I didn't have network I couldn't access it remotely anymore at a certain point the electricity was restored (and the UPS charge could keep the server up), however the server accessibility did not due restore until I asked a relative to restart it or under a more complicated cases where Tech aquanted guy has to help – Alexander (Alex) a close friend from school years check his old site here – alex.pc-freak.net helps a lot.to restart the machine physically either run a quick restoration commands on root TTY terminal or generally do check whether default router is reachable.

This kind of Pc-Freak.net downtime issues over the last month become too frequent (the machine was down about 5 times for 2 to 5 hours and this was too much (and weirdly enough it was not accessible from the internet even after electricity network was restored and the only solution to that was a physical server restart (from the Power Button).

To decrease the number of cases in which known relatives or friends has to  physically go to the server and restart it, each time after network or electricity outage I wrote a small script to check accessibility towards Default defined Network Gateway for my server with few ICMP packages sent with good old PING command
and trigger a network restart and system reboot
(in case if the network restart does fail) in a row.

1. Create reboot-if-nwork-is-downsh script under /usr/sbin or other dir

Here is the script itself:

 

#!/bin/sh
# Script checks with ping 5 ICMP pings 10 times to DEF GW and if so
# triggers networking restart /etc/inid.d/networking restart
# Then does another 5 x 10 PINGS and if ping command returns errors,
# Reboots machine
# This script is useful if you run home router with Linux and you have
# electricity outages and machine doesn't go up if not rebooted in that case

GATEWAY_HOST='192.168.0.1';

run_ping () {
for i in $(seq 1 10); do
    ping -c 5 $GATEWAY_HOST
done

}

reboot_f () {
if [ $? -eq 0 ]; then
        echo "$(date "+%Y-%m-%d %H:%M:%S") Ping to $GATEWAY_HOST OK" >> /var/log/reboot.log
    else
    /etc/init.d/networking restart
        echo "$(date "+%Y-%m-%d %H:%M:%S") Restarted Network Interfaces:" >> /tmp/rebooted.txt
    for i in $(seq 1 10); do ping -c 5 $GATEWAY_HOST; done
    if [ $? -eq 0 ] && [ $(cat /tmp/rebooted.txt) -lt ‘5’ ]; then
         echo "$(date "+%Y-%m-%d %H:%M:%S") Ping to $GATEWAY_HOST FAILED !!! REBOOTING." >> /var/log/reboot.log
        /sbin/reboot

    # increment 5 times until stop
    [[ -f /tmp/rebooted.txt ]] || echo 0 > /tmp/rebooted.txt
    n=$(< /tmp/rebooted.txt)
        echo $(( n + 1 )) > /tmp/rebooted.txt
    fi
    # if 5 times rebooted sleep 30 mins and reset counter
    if [ $(cat /tmprebooted.txt) -eq ‘5’ ]; then
    sleep 1800
        cat /dev/null > /tmp/rebooted.txt
    fi
fi

}
run_ping;
reboot_f;

You can download a copy of reboot-if-nwork-is-down.sh script here.

As you see in script successful runs  as well as its failures are logged on server in /var/log/reboot.log with respective timestamp.
Also a counter to 5 is kept in /tmp/rebooted.txt, incremented on each and every script run (rebooting) if, the 5 times increment is matched

a sleep is executed for 30 minutes and the counter is being restarted.
The counter check to 5 guarantees the server will not get restarted if access to Gateway is not continuing for a long time to prevent the system is not being restarted like crazy all time.
 

2. Create a cron job to run reboot-if-nwork-is-down.sh every 15 minutes or so 

I've set the script to re-run in a scheduled (root user) cron job every 15 minutes with following  job:

To add the script to the existing cron rules without rewriting my old cron jobs and without tempering to use cronta -u root -e (e.g. do the cron job add in a non-interactive mode with a single bash script one liner had to run following command:

 

{ crontab -l; echo "*/15 * * * * /usr/sbin/reboot-if-nwork-is-down.sh 2>&1 >/dev/null; } | crontab –


I know restarting a server to restore accessibility is a stupid practice but for home-use or small client servers with unguaranteed networks with a cheap Uninterruptable Power Supply (UPS) devices it is useful.

Summary

Time will show how efficient such a  "self-healing script practice is.
Even though I'm pretty sure that even in a Corporate businesses and large Public / Private Hybrid Clouds where access to remote mounted NFS / XFS / ZFS filesystems are failing a modifications of the script could save you a lot of nerves and troubles and unhappy customers / managers screaming at you on the phone 🙂


I'll be interested to hear from others who have a better  ideas to restore ( resurrect ) access to inessible Linux server after an outage.?
 

Prevent rsync cronjob to run multiple times via cronjob on Linux

Wednesday, November 21st, 2018

prevent-rsync-rsync-to-run-multiple-times-via-cronjob-on-linux

Today I had a report of a server whose Load Avarage keeps at the high level of 86, the machine runs on a bare metal rock solid hardware and even with such high Loads of the kernel it runs fine, but due to the I/O overhead the SANs red from a remote NetApp storage device started to be sluggish and hence it needed to be reviewed, thus I jumped in via the hop station (jump host) into the server.
 

1. Short investation on root cause for high server load


After a short investigation, I've found an rsync job set by someone on a cron job to be routinely run every 30 minutes, thus the old scheduled rsync, which seemed to run multiple times on the server (about 50 processes) of same rsync (file system synchronization was running) and as expected the storage was saddled with mutiple Input / Output requests.

The root cron job was like that:
 

server:~# crontab -u root -l |grep -i rsync
/usr/bin/rsync -ax /var/www/htdocs/directory_to_synchronize / /srv/www/synch_back/directory_to_synchrnize


A process list showed the following high number of running mirrored rsyncs:

 

server:~# ps axuwwf | grep -i rsync | wc -l
80


 

2. The Fix – Set Rsync to only via cron only in case if it is not already running in background


In order to fix it, I had to kill all current running rsync (here luckily only same single instance of rsync was running, but generally I was cautious to check no other rsync jobs are running – otherwise I would have mistakenly killed some other rsync job ongoing …)

Then I set the following new cron job one liner quick shell script that does the job to assign a pid file that is created before rsync and deleted after rsync completion.
 

if [ ! -e /tmp/repo_dba_sync.lock ]; then touch /tmp/repo_dba_sync.lock; /usr/bin/rsync -ax /var/www/htdocs/directory_to_synchronize / /srv/www/synch_back/directory_to_synchrnize ; trap 'rm -f /tmp/repo_dba_sync.lock; fi' EXIT  >/dev/null 2>&1


The cron job looked like so:

 

*/30 * * * * if [ ! -e /tmp/repo_dba_sync.lock ]; then touch /tmp/repo_dba_sync.lock; /usr/bin/rsync -ax /var/www/htdocs/directory_to_synchronize / /srv/www/synch_back/directory_to_synchrnize ; trap 'rm -f /tmp/repo_dba_sync.lock; fi'  EXIT >/dev/null 2>&1

Just in case if you're wondering
a trap should be used to verify that the lock file is removed when the script is exited for any reason.
This way the lock file will be removed even if the script exits before the end of the script.

An alternative and more simple ways to do it is via:
 

pgrep rsync > /dev/null || rsync -ax /var/www/htdocs/directory_to_synchronize / /srv/www/synch_back/directory_to_synchrnize

 

Or if you don't want to use bash's:
 

if []; then; fi


condition but still use a file lock the flock command can be used like so:
 

flock -n lock_file -c "rsync …"

Ansible Quick Start Cheatsheet for Linux admins and DevOps engineers

Wednesday, October 24th, 2018

ansible-quick-start-cheetsheet-ansible-logo

Ansible is widely used (Configuration management, deployment, and task execution system) nowadays for mass service depoyments on multiple servers and Clustered environments like, Kubernetes clusters (with multiple pods replicas) virtual swarms running XEN / IPKVM virtualization hosting multiple nodes etc. .

Ansible can be used to configure or deploy GNU / Linux tools and services such as Apache / Squid / Nginx / MySQL / PostgreSQL. etc. It is pretty much like Puppet (server / services lifecycle management) tool , except its less-complecated to start with makes it often a choose as a tool for mass deployment (devops) automation.

Ansible is used for multi-node deployments and remote-task execution on group of servers, the big pro of it it does all its stuff over simple SSH on the remote nodes (servers) and does not require extra services or listening daemons like with Puppet. It combined with Docker containerization is used very much for later deploying later on inside Cloud environments such as Amazon AWS / Google Cloud Platform / SAP HANA / OpenStack etc.

Ansible-Architechture-What-Is-Ansible-Edureka

0. Instaling ansible on Debian / Ubuntu Linux


Ansible is a python script and because of that depends heavily on python so to make it running, you will need to have a working python installed on local and remote servers.

Ansible is as easy to install as running the apt cmd:

 

# apt-get install –yes ansible
 

The following additional packages will be installed:
  ieee-data python-jinja2 python-kerberos python-markupsafe python-netaddr python-paramiko python-selinux python-xmltodict python-yaml
Suggested packages:
  sshpass python-jinja2-doc ipython python-netaddr-docs python-gssapi
Recommended packages:
  python-winrm
The following NEW packages will be installed:
  ansible ieee-data python-jinja2 python-kerberos python-markupsafe python-netaddr python-paramiko python-selinux python-xmltodict python-yaml
0 upgraded, 10 newly installed, 0 to remove and 1 not upgraded.
Need to get 3,413 kB of archives.
After this operation, 22.8 MB of additional disk space will be used.

apt-get install –yes sshpass

 

Installing Ansible on Fedora Linux is done with:

 

# dnf install ansible –yes sshpass

 

On CentOS to install:
 

# yum install ansible –yes sshpass

sshpass needs to be installed only if you plan to use ssh password prompt authentication with ansible.

Ansible is also installable via python-pip tool, if you need to install a specific version of ansible you have to use it instead, the package is available as an installable package on most linux distros.

Ansible has a lot of pros and cons and there are multiple articles already written on people for and against it in favour of Chef or Puppet As I recently started learning Ansible. The most important thing to know about Ansible is though many of the things can be done directly using a simple command line, the tool is planned for remote installing of server services using a specially prepared .yaml format configuration files. The power of Ansible comes of the use of Ansible Playbooks which are yaml scripts that tells ansible how to do its activities step by step on remote server. In this article, I'm giving a quick cheat sheet to start quickly with it.
 

1. Remote commands execution with Ansible
 

First thing to do to start with it is to add the desired hostnames ansible will operate with it can be done either globally (if you have a number of remote nodes) to deploy stuff periodically by using /etc/ansible/hosts or use a custom host script for each and every ansible custom scripts developed.

a. Ansible main config files

A common ansible /etc/ansible/hosts definition looks something like that:

 

# cat /etc/ansible/hosts
[mysqldb]
10.69.2.185
10.69.2.186
[master]
10.69.2.181
[slave]
10.69.2.187
[db-servers]
10.69.2.181
10.69.2.187
[squid]
10.69.2.184

Host to execute on can be also provided via a shell variable $ANSIBLE_HOSTS
b) is remote hosts reachable / execute commands on all remote host

To test whether hour hosts are properly configure from /etc/ansible/hosts you can ping all defined hosts with:

 

ansible all -m ping


ansible-check-hosts-ping-command-screenshot

This makes ansible try to remote to remote hosts (if you have properly configured SSH public key authorization) the command should return success statuses on every host.

 

ansible all -a "ifconfig -a"


If you don't have SSH keys configured you can also authenticate with an argument (assuming) all hosts are configured with same password with:

 

ansible all –ask-pass -a "ip all show" -u hipo –ask-pass


ansible-show-ips-ip-a-command-screenshot-linux

If you have configured group of hosts via hosts file you can also run certain commands on just a certain host group, like so:

 

ansible <host-group> -a <command>

It is a good idea to always check /etc/ansible/ansible.cfg which is the system global (main red ansible config file).

c) List defined host groups
 

ansible localhost -m debug -a 'var=groups.keys()'
ansible localhost -m debug -a 'var=groups'

d) Searching remote server variables

 

# Search remote server variables
ansible localhost -m setup -a 'filter=*ipv4*'

 

 

ansible localhost -m setup -a 'filter=ansible_domain'

 

 

ansible all -m setup -a 'filter=ansible_domain'

 

 

# uninstall package on RPM based distros
ansible centos -s -m yum -a "name=telnet state=absent"
# uninstall package on APT distro
ansible localhost -s -m apt -a "name=telnet state=absent"

 

 

2. Debugging – Listing information about remote hosts (facts) and state of a host

 

# All facts for one host
ansible -m setup
  # Only ansible fact for one host
ansible
-m setup -a 'filter=ansible_eth*'
# Only facter facts but for all hosts
ansible all -m setup -a 'filter=facter_*'


To Save outputted information per-host in separate files in lets say ~/ansible/host_facts

 

ansible all -m setup –tree ~/ansible/host_facts

 

3. Playing with Playbooks deployment scripts

 

a) Syntax Check of a playbook yaml

 

ansible-playbook –syntax-check


b) Run General Infos about a playbook such as get what a playbook would do on remote hosts (tasks to run) and list-hosts defined for a playbook (like above pinging).

 

ansible-playbook –list-hosts
ansible-playbook
–list-tasks


To get the idea about what an yaml playbook looks like, here is example from official ansible docs, that deploys on remote defined hosts a simple Apache webserver.
 


– hosts: webservers
  vars:
    http_port: 80
    max_clients: 200
  remote_user: root
  tasks:
  – name: ensure apache is at the latest version
    yum:
      name: httpd
      state: latest
  – name: write the apache config file
    template:
      src: /srv/httpd.j2
      dest: /etc/httpd.conf
    notify:
    – restart apache
  – name: ensure apache is running
    service:
      name: httpd
      state: started
  handlers:
    – name: restart apache
      service:
        name: httpd
        state: restarted

To give it a quick try save the file as webserver.yml and give it a run via ansible-playbook command
 

ansible-playbook -s playbooks/webserver.yml

 

The -s option instructs ansible to run play on remote server with super user (root) privileges.

The power of ansible is its modules, which are constantly growing over time a complete set of Ansible supported modules is in its official documenation.

Ansible-running-playbook-Commands-Task-script-Successful-output-1024x536

There is a lot of things to say about playbooks, just to give the brief they have there own language like a  templates, tasks, handlers, a playbook could have one or multiple plays inside (for instance instructions for deployment of one or more services).

The downsides of playbooks are they're so hard to write from scratch and edit, because yaml syntaxing is much more stricter than a normal oldschool sysadmin configuration file.
I've stucked with problems with modifying and writting .yaml files and I should say the community in #ansible in irc.freenode.net was very helpful to help me debug the obscure errors.

yamllint (The YAML Linter tool) comes handy at times, when facing yaml syntax errors, to use it install via apt:
 

# apt-get install –yes yamllint


a) Running ansible in "dry mode" just show what ansible might do but not change anything
 

ansible-playbook playbooks/PLAYBOOK_NAME.yml –check


b) Running playbook with different users and separate SSH keys

 

ansible-playbook playbooks/your_playbook.yml –user ansible-user
 
ansible -m ping hosts –private-key=~/.ssh/keys/custom_id_rsa -u centos

 

c) Running ansible playbook only for certain hostnames part of a bigger host group

 

ansible-playbook playbooks/PLAYBOOK_NAME.yml –limit "host1,host2,host3"


d) Run Ansible on remote hosts in parallel

To run in raw of 10 hosts in parallel
 

# Run 10 hosts parallel
ansible-playbook <File.yaml> -f 10            


e) Passing variables to .yaml scripts using commandline

Ansible has ability to pre-define variables from .yml playbooks. This variables later can be passed from shell cli, here is an example:

# Example of variable substitution pass from command line the var in varsubsts.yaml if present is defined / replaced ansible-playbook playbooks/varsubst.yaml –extra-vars "myhosts=localhost gather=yes pkg=telnet"

 

4. Ansible Galaxy (A Docker Hub) like large repository with playbook (script) files

 

Ansible Galaxy has about 10000 active users which are contributing ansible automation playbooks in fields such as Development / Networking / Cloud / Monitoring / Database / Web / Security etc.

To install from ansible galaxy use ansible-galaxy

# install from galaxy the geerlingguy mysql playbook
ansible-galaxy install geerlingguy.mysql


The available packages you can use as a template for your purpose are not so much as with Puppet as Ansible is younger and not corporate supported like Puppet, anyhow they are a lot and does cover most basic sysadmin needs for mass deployments, besides there are plenty of other unofficial yaml ansible scripts in various github repos.

How to make Reverse SSH Tunnel to servers behind NAT

Thursday, October 11th, 2018

create-reverse-ssh-tunnel-reverse_ssh_diagram-connection

Those who remember the times of IRC chatting long nights and the need to be c00l guy and enter favorite IRC server through a really bizarre hostname, you should certainly remember the usefulness of Reverse SSH Tunnels to appear in IRC /whois like connecting from a remote host (mask yourself) from other IRC guys where are you physically.

The idea of Reverse SSH is to be able to SSH (or other protocols) connect to IPs that are situated behind a NAT server/s.
Creating SSH Reverse Tunnel is an easy task and up to 2 simple SSH commands
,

To better explain how SSH tunnel is achieved, here is a scenario:

A. Linux host behind NAT IP: 192.168.10.70 (Destination host)
B. (Source Host) of Machine with External Public Internet IP 83.228.93.76 through which SSH Tunnel will be established to 192.168.10.70.

1. Create SSH Revere SSH from Destination to Source host (with Public IP)

Connect to the remote machine which has a real IP address and make port of the reverse SSH connection open (remove any firewall), lets say port 23000.

ssh -R 23000:127.0.0.1:22 username@DOMAIN.com -oPort=33

NB! On destination and source servers make sure you have enabled in /etc/ssh/sshd_config
 

AllowAgentForwarding yes
AllowTCPForwarding yes
PermitTunnel yes

 


2. Connect from Source IP to Destination through the established SSH tunnelling

 

 

Connecting to DOMAIN.com through ssh on 23000 will connect you to the back machine with the unreal IP address.
 

ssh local-username@127.0.0.1 -p 23000


ssh -L 19999:localhost:19999 middleman@178.78.78.78

If you want other server with hostname whatever-host.com to access the Reverse SSH Tunneled server you can do it via external IP which in my case is 83.228.93.76

From whatever-host.com just do:

 ssh username@82.228.93.76

 

reverse_tunnel-linux-diagram-explained
A text diagram of SSH Tunnel looks something like that:

Destination (192.168.10.70) <- |NAT| <- Source (83.228.93.76) <- whatever-host.com

 

Above examples should work not only on Linux but on NetBSD / OpenBSD / FreeBSD or any other UNIX system with a modern SSH client installed.

Display Content of SSL certificate .pem file with openssl command

Thursday, October 11th, 2018

display-content-of-pem-der-and-scr-file-how-to-view-pem-file-linux

If you have generated a .pem formatted SSL certificate or you have multiple .pem SSL certificates and you're not sure which .pem file is generated for which domain / subdomain it is useful to Display content of SSL Certificate .PEM file with openssl command.

Viewing certificate's content is also very useful if you have hosted multiple websites hosted on a server and you want to check which of the SSLs assigned in the Virtualhosts has Expired (for example if you have domains that expire in short term period (365 days).


1. How to Display Content of SSL certificate .pem file?

 

root@pcfreak:~# openssl x509 -in cert.pem -text
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            04:d1:ad:55:91:f3:f9:ef:3e:53:ea:2c:3a:f4:5f:e6:ce:c1
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C = US, O = Let's Encrypt, CN = Let's Encrypt Authority X3
        Validity
            Not Before: Oct 10 17:49:34 2018 GMT
            Not After : Jan  8 17:49:34 2019 GMT
        Subject: CN = mail.pc-freak.net

        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:bb:b0:c9:1c:83:82:61:47:f9:c2:73:60:c0:48:
                    e6:0c:f2:a1:ff:db:ae:f1:84:17:14:5d:fc:a3:b2:
                    e4:00:3a:d1:85:42:90:da:41:a9:e9:a8:af:20:3d:
                    12:ef:8e:ca:61:a1:71:f2:cc:43:bf:40:0d:fa:08:
                    7d:d9:61:2b:ea:5d:30:e0:52:43:db:18:30:92:0c:
                    2c:ce:87:93:84:ea:91:61:b7:70:db:11:7c:b6:a4:
                    33:de:d8:3f:d6:61:47:42:f2:36:12:7f:3d:e3:f7:
                    5b:11:3e:1c:f0:af:96:cd:61:8a:1a:a0:f0:b5:23:
                    65:73:b6:b4:9c:19:a7:09:dd:43:96:37:ac:48:fc:
                    21:07:02:52:67:26:2c:81:24:f4:d7:10:e6:f4:12:
                    69:53:ef:91:2a:15:6a:21:06:22:ea:fe:31:38:82:
                    b4:5a:b5:9b:67:90:16:b8:31:e8:27:38:f2:41:b9:
                    19:02:8f:c7:6e:e1:2c:84:75:19:6d:bb:30:3b:d2:
                    02:f0:65:f1:76:82:15:9c:ce:31:3a:d4:7c:83:ca:
                    d1:f9:e1:b7:76:f6:78:93:47:d2:00:f9:63:aa:94:
                    41:d4:78:d0:ee:bc:e6:e9:14:14:e4:ae:54:31:88:
                    f8:58:8d:7b:3e:9f:87:5c:f2:04:e5:07:e0:4c:9a:
                    81:eb
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Extended Key Usage:
                TLS Web Server Authentication, TLS Web Client Authentication
            X509v3 Basic Constraints: critical
                CA:FALSE
            X509v3 Subject Key Identifier:
                DB:AB:81:E3:14:5F:6D:BE:B4:78:7B:5E:7D:FB:66:BF:56:37:C5:1D
            X509v3 Authority Key Identifier:
                keyid:A8:4A:6A:63:04:7D:DD:BA:E6:D1:39:B7:A6:45:65:EF:F3:A8:EC:A1

 

            Authority Information Access:
                OCSP – URI:http://ocsp.int-x3.letsencrypt.org
                CA Issuers – URI:http://cert.int-x3.letsencrypt.org/

            X509v3 Subject Alternative Name:
                DNS:mail.pc-freak.net
            X509v3 Certificate Policies:
                Policy: 2.23.140.1.2.1
                Policy: 1.3.6.1.4.1.44947.1.1.1
                  CPS: http://cps.letsencrypt.org
                  User Notice:
                    Explicit Text: This Certificate may only be relied upon by Relying Parties and only in accordance with the Certificate Policy found at https://letsencrypt.org/repository/

            CT Precertificate SCTs:
                Signed Certificate Timestamp:
                    Version   : v1 (0x0)
                    Log ID    : E2:69:4B:AE:26:E8:E9:40:09:E8:86:1B:B6:3B:83:D4:
                                3E:E7:FE:74:88:FB:A4:8F:28:93:01:9D:DD:F1:DB:FE
                    Timestamp : Oct 10 18:49:34.453 2018 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:46:02:21:00:D6:DE:47:AD:D2:32:BE:BE:DD:B3:EB:
                                EE:84:9E:02:8A:4F:33:E2:63:21:D5:F7:4D:47:82:92:
                                AB:B9:0A:49:62:02:21:00:E8:7D:17:81:32:E3:4F:CF:
                                2D:79:8C:97:46:E1:EF:5E:99:F4:8A:8B:B5:6D:23:5F:
                                05:84:E2:14:6A:56:8E:A0
                Signed Certificate Timestamp:
                    Version   : v1 (0x0)
                    Log ID    : 29:3C:51:96:54:C8:39:65:BA:AA:50:FC:58:07:D4:B7:
                                6F:BF:58:7A:29:72:DC:A4:C3:0C:F4:E5:45:47:F4:78
                    Timestamp : Oct 10 18:49:34.451 2018 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:44:02:20:6C:8E:E7:E2:70:AD:33:A6:5C:E0:89:84:
                                FB:0B:F6:E1:5C:05:06:0A:A8:DB:8B:1C:7A:D0:52:99:
                                5F:3F:A2:64:02:20:4B:CD:0B:E7:A0:27:04:31:19:18:
                                58:99:51:73:49:6B:77:25:A7:E7:5B:10:8C:BD:ED:54:
                                03:DD:40:E4:2D:31
    Signature Algorithm: sha256WithRSAEncryption
         9c:86:b3:34:64:af:ac:9d:c4:d3:a7:cc:fc:8a:32:18:75:95:
         95:47:9b:9c:3c:0e:3b:61:f9:88:61:38:1a:a6:92:69:3d:14:
         6a:53:13:14:65:e6:ca:fa:b9:8e:48:c9:d4:73:f6:e4:74:8a:
         1f:2b:f2:14:86:f1:18:55:26:1b:a0:97:89:15:0b:62:c6:2b:
         27:81:6f:60:af:55:68:b3:2c:5b:10:56:a2:7d:28:cb:8e:fc:
         f0:21:65:78:9b:3a:52:d3:9d:27:ff:d7:24:95:de:0f:d8:3d:
         a2:43:6e:fc:a5:2d:f2:ad:37:e9:ea:db:b5:75:b8:7c:ad:23:
         45:1d:bd:fe:4e:36:c7:f4:e2:3d:47:c9:06:fc:cb:75:ba:d4:
         0a:90:17:ea:e1:7f:49:e6:68:27:97:8a:70:c7:50:e9:19:4a:
         8a:21:18:26:79:a3:61:ff:1b:26:9e:fe:85:8f:20:ed:c6:4d:
         c1:0e:04:21:a8:05:d4:29:69:99:53:63:81:c7:d5:58:71:df:
         02:b5:94:c9:36:48:c9:35:80:ab:71:78:d9:12:f6:f5:10:25:
         3d:38:c5:40:75:25:b1:95:18:d8:1c:96:f1:c6:1a:d2:c4:99:
         f5:01:2e:f4:e1:4a:1f:10:42:0e:34:ed:92:8e:53:9f:c2:7b:
         11:51:78:6a
—–BEGIN CERTIFICATE—–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—–END CERTIFICATE—–

 

Same way a .der files content / encryption algorithm and domain name could be grasped.
 

root@pcfreak:~# openssl x509 -in cert.der -inform der -text
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            ad:c2:96:6f:4b:db:31:5c
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN = example.com
        Validity
            Not Before: Jun 22 04:00:37 2015 GMT
            Not After : Jul 22 04:00:37 2015 GMT

        Subject: CN = example.com
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (512 bit)

                Modulus:
                    00:ac:75:73:b4:51:ed:1f:dd:ae:70:52:43:fc:df:
                    c7:5b:d0:2c:75:1b:14:b8:75:01:04:10:e5:1f:03:
                    65:45:dd:df:a7:9f:34:ae:fd:be:e9:05:84:df:47:
                    16:81:d9:89:4b:ce:8e:6d:1c:fa:95:44:e8:af:84:
                    74:4f:ed:c2:e5
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Subject Key Identifier:
                26:CF:C8:ED:4B:D7:94:B2:E4:25:03:58:24:8F:04:C0:74:D5:97:8A
            X509v3 Authority Key Identifier:
                keyid:26:CF:C8:ED:4B:D7:94:B2:E4:25:03:58:24:8F:04:C0:74:D5:97:8A

 

            X509v3 Basic Constraints:
                CA:TRUE
    Signature Algorithm: sha256WithRSAEncryption
         0c:8b:ff:12:80:9e:4c:90:bc:26:b0:96:20:ab:76:0c:64:71:
         d2:15:48:a5:33:f6:47:e4:03:df:76:5e:0f:cd:e1:1b:5e:d1:
         4d:c2:1f:8d:b8:63:2f:c9:7d:6e:5c:3b:cb:cd:a3:d0:d8:27:
         74:66:a3:76:06:a5:fb:81:3a:b6
—–BEGIN CERTIFICATE—–
MIIBdTCCAR+gAwIBAgIJAK3Clm9L2zFcMA0GCSqGSIb3DQEBCwUAMBYxFDASBgNV
BAMMC2V4YW1wbGUuY29tMB4XDTE1MDYyMjA0MDAzN1oXDTE1MDcyMjA0MDAzN1ow
FjEUMBIGA1UEAwwLZXhhbXBsZS5jb20wXDANBgkqhkiG9w0BAQEFAANLADBIAkEA
rHVztFHtH92ucFJD/N/HW9AsdRsUuHUBBBDlHwNlRd3fp580rv2+6QWE30cWgdmJ
S86ObRz6lUTor4R0T+3C5QIDAQABo1AwTjAdBgNVHQ4EFgQUJs/I7UvXlLLkJQNY
JI8EwHTVl4owHwYDVR0jBBgwFoAUJs/I7UvXlLLkJQNYJI8EwHTVl4owDAYDVR0T
BAUwAwEB/zANBgkqhkiG9w0BAQsFAANBAAyL/xKAnkyQvCawliCrdgxkcdIVSKUz
9kfkA992Xg/N4Rte0U3CH424Yy/JfW5cO8vNo9DYJ3Rmo3YGpfuBOrY=
—–END CERTIFICATE—–

 

2. How to display content and info about .CSR (Certificate Signing request)

 

root@pcfreak:~# openssl req -in cert.csr -noout -text
 

Certificate Request:
    Data:
        Version: 1 (0x0)
        Subject: C = BG, ST = BG, L = Dobrich, O = Pc Freak, CN = mail.pc-freak.net, emailAddress = hipo@pc-freak.net
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:b1:83:a7:07:62:19:d4:60:95:58:49:de:b3:48:
                    a8:39:31:fa:5a:bd:2b:d6:73:94:50:36:72:74:18:
                    58:b6:27:d3:0b:26:75:15:a8:ba:1b:77:a7:c9:54:
                    96:1f:c7:8d:da:bd:c9:17:91:53:85:9e:0a:f4:71:
                    3c:fb:d6:e4:75:41:c1:95:32:e1:22:fc:7b:1f:36:
                    23:12:00:ca:37:27:d5:f9:9b:29:48:4a:51:95:d1:
                    40:d0:ea:94:51:98:98:6b:d3:d9:79:1d:a1:65:bb:
                    a9:d1:ab:c9:46:6e:03:ee:24:45:e5:f2:73:e5:f4:
                    82:4a:08:57:b1:06:52:c3:cc:42:9a:02:5b:7a:7c:
                    bd:34:d5:5f:d7:ba:ef:27:d5:3d:97:16:69:06:c7:
                    c1:06:5e:d9:07:16:3f:a3:61:50:9d:dd:ea:95:32:
                    f1:ee:93:82:48:df:20:8b:ae:d2:95:89:05:e4:3d:
                    0c:d7:e1:cf:07:ae:55:84:11:06:92:be:34:b4:a2:
                    a1:ce:07:06:bf:21:bc:80:e2:03:d2:85:b4:64:02:
                    8d:cd:d2:86:1c:49:41:52:43:a8:12:f8:ef:2c:f4:
                    be:a0:dc:ac:ea:27:3a:f9:ab:ab:27:da:28:63:1d:
                    10:5a:4f:b8:51:42:40:ae:be:c0:2d:e9:a3:5a:5a:
                    23:7f
                Exponent: 65537 (0x10001)
        Attributes:
            a0:00
    Signature Algorithm: sha256WithRSAEncryption
         47:f0:54:cd:5e:46:6f:2c:cc:48:7e:85:f0:a8:96:10:ca:a3:
         15:98:77:d3:02:95:8c:67:84:e3:55:d2:0c:e8:d5:a7:ba:82:
         95:fb:ce:73:4c:bc:8f:da:85:97:0c:a8:59:32:b3:a4:af:0a:
         80:4c:78:7f:62:cd:1b:00:01:e8:51:27:9c:eb:75:29:80:e9:
         99:24:fc:86:e2:09:28:be:47:5a:1d:bf:b1:b4:c4:29:4e:6e:
         f3:70:b4:58:f8:d9:a6:63:03:8b:a1:ef:ee:6d:1a:35:33:1e:
         b2:32:25:c1:33:37:3d:46:82:37:9b:0d:4c:40:20:ae:ff:e0:
         cc:51:a2:6b:dd:74:26:d6:93:26:89:c7:76:29:13:cf:6e:5a:
         0f:7c:1b:f5:80:be:3b:6a:a3:c0:10:cd:07:1e:a2:31:8b:49:
         94:d7:63:cf:93:8d:80:03:75:4a:76:b4:cd:14:fe:96:62:61:
         6b:96:8f:c0:a5:ef:67:c7:5e:c0:a5:4b:4f:95:57:b6:43:03:
         8b:6d:10:5f:ab:f2:95:54:ba:85:8e:8b:c1:99:ea:fd:3f:5e:
         23:01:d4:27:f3:e9:20:37:c4:05:47:30:67:94:53:f0:87:27:
         48:73:57:55:f2:70:04:b1:e9:29:eb:2e:2c:9a:cc:55:f4:cc:
         a4:71:c2:5a


That's all folks 🙂

 

Preparing your Linux to work with the Cloud providers – Installing aws , gcloud, az, oc, cf CLI Cloud access command interfaces

Wednesday, October 10th, 2018

howto Install-Cloud-access-tools-for-google-aws-azure-openshift-cloud-foundryCloud_computing-explained-on-linux.svg

If you're a sysadmin / developer whose boss requires a migration of Stored Data, Database structures or Web Objects to Amazon Web Services / Google Clourd or you happen to be a DevOps Engineer you will certainly need to have installed as a minimumum amazon AWS and Google Clouds clients to do daily routines and script stuff in managing cloud resources without tampering to use the Web GUI interface.

Here is how to install the aws, gcloud, oc, az and cf next to your kubernetes client (kubectl) on your Linux Desktop.
 

1. Install Google Cloud  gcloud (to manage Google Cloud platform resources and developer workflow
 

google-cloud-logo

Here is few cmds to run to install  gcloud, gcloud alpha, gcloud beta, gsutil, and bq commands to manage your Google Cloud from CLI

a.) On Debian / Ubuntu / Mint or any other deb based distro

# Create environment variable for correct distribution
export CLOUD_SDK_REPO="cloud-sdk-$(lsb_release -c -s)"

 

# Add the Cloud SDK distribution URI as a package source
# echo "deb http://packages.cloud.google.com/apt $CLOUD_SDK_REPO main" | sudo tee -a /etc/apt/sources.list.d/google-cloud-sdk.list

 

# Import the Google Cloud Platform public key
$ sudo curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add –

 

# Update the package list and install the Cloud SDK
$ sudo apt-get update && sudo apt-get install google-cloud-sdk


b) On CentOS, RHEL, Fedora Linux and other rpm based ones
 

$ sudo tee -a /etc/yum.repos.d/google-cloud-sdk.repo << EOM
[google-cloud-sdk]
name=Google Cloud SDK
baseurl=https://packages.cloud.google.com/yum/repos/cloud-sdk-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg
       https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOM

# yum install google-cloud-sdk

 

That's all now the text client to talk to Google Cloud's API gcloud is installed under
/usr/bin/gcloud

Latest install instructions of Google Cloud SDK are here.


2. Install AWS Cloud command line interface tool for managing AWS (Amazon Web Services)
 

AmazonWebservices_Logo.svg

AWS client is dependent on Python PIP so before you proceed you will have to install python-pip deb package if on Debian / Ubuntu Linux use apt:

 

# apt-get install –yes python-pip

 

It is also possible to install newest version of PIP a tiny shell script provided by Amazon get-pip.py

 

# curl -O https://bootstrap.pypa.io/get-pip.py
# python get-pip.py –user

 

# pip install awscli –upgrade –user

 

3. Install Azure Cloud Console access CLI command interface
 

Microsoft_Azure_Cloud-Logo.svg

On Debian / Ubuntu or any other deb based distro:

# AZ_REPO=$(lsb_release -cs)
# echo "deb [arch=amd64] https://packages.microsoft.com/repos/azure-cli/ $AZ_REPO main" | \
$ sudo tee /etc/apt/sources.list.d/azure-cli.list

# curl -L https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add –
$ sudo apt-get update
$ sudo apt-get install apt-transport-https azure-cli

 

Finaly to check that Azure CLI is properly installed run simple login with:

 

$ az login

 


$ sudo rpm –import https://packages.microsoft.com/keys/microsoft.asc
$ sudo sh -c 'echo -e "[azure-cli]\nname=Azure CLI\nbaseurl=https://packages.microsoft.com/yumrepos/azure-cli\nenabled=1\ngpgcheck=1\ngpgkey=https://packages.microsoft.com/keys/microsoft.asc" > /etc/yum.repos.d/azure-cli.repo'
$ sudo yum install azure-cli

$ az login


For Latest install instructions check Amazon's documentation here

4. Install OpenShift OC CLI tool to access OpenShift Open Source Cloud

 

OpenShift-Redhat-cloud-platform

Even thought OpenShift has its original Redhat produced package binaries, if you're not on RPM distro it is probably
best to install using official latest version from openshift github repo.


As of time of writting this article this is done with:

 

# wget https://github.com/openshift/origin/releases/download/v1.5.1/openshift-origin-client-tools-v1.5.1-7b451fc-linux-64bit.tar.gz
tar –xvf openshift-origin-client-tools-v1.5.1-7b451fc-linux-64bit.tar.gz

 

# # mv openshift-origin-client-tools-v1.5.1-7b451fc-linux-64bit oc-tool

 

# cd oc-tool
# echo'export PATH=$HOME/oc-tool:$PATH' >> ~/.bashrc

 

To test openshift, try to login to OpenShift cloud:

 

$ oc login
Server [https://localhost:8443]: https://128.XX.XX.XX:8443


Latest install instructions on OC here

5. Install Cloud Foundry cf CLI Cloud access tool

cloud-foundry-cloud-logo

a) On Debian / Ubuntu Linux based distributions, do run:

 

$ wget -q -O – https://packages.cloudfoundry.org/debian/cli.cloudfoundry.org.key | sudo apt-key add –
$ echo "deb https://packages.cloudfoundry.org/debian stable main" | sudo tee /etc/apt/sources.list.d/cloudfoundry-cli.list
$ sudo apt-get update
$ sudo apt-get install cf-cli

 

b) On RHEL Enterprise Linux / CentOS and Fedoras

 

$ sudo wget -O /etc/yum.repos.d/cloudfoundry-cli.repo https://packages.cloudfoundry.org/fedora/cloudfoundry-cli.repo
$ sudo yum install cf-cli


For latest install insructions on cf cli check Cloud Foundry's install site

There plenty of other Cloud providers with the number exponentially growing and most have their own custom cli tools to access but as there use is not so common as the 5 ones mentioned below, I've omited 'em. If you're interested to know the complete list of Cloud Providers providing Cloud Services check here.

6. Install Ruby GEMs RHC tools collection

If you have to work with Redhat Cloud Storage / OpenShift you will perhaps want to install also (RHC) Redhat Collection Tools.

Assuming that the Linux system is running an up2date version of ruby programming language do run:

 

 

root@jeremiah:~# gem install rhc
Fetching: net-ssh-5.0.2.gem (100%)
Successfully installed net-ssh-5.0.2
Fetching: net-ssh-gateway-2.0.0.gem (100%)
Successfully installed net-ssh-gateway-2.0.0
Fetching: net-ssh-multi-1.2.1.gem (100%)
Successfully installed net-ssh-multi-1.2.1
Fetching: minitar-0.7.gem (100%)
The `minitar` executable is no longer bundled with `minitar`. If you are
expecting this executable, make sure you also install `minitar-cli`.
Successfully installed minitar-0.7
Fetching: hashie-3.6.0.gem (100%)
Successfully installed hashie-3.6.0
Fetching: powerbar-1.0.18.gem (100%)
Successfully installed powerbar-1.0.18
Fetching: minitar-cli-0.7.gem (100%)
Successfully installed minitar-cli-0.7
Fetching: archive-tar-minitar-0.6.1.gem (100%)
'archive-tar-minitar' has been deprecated; just install 'minitar'.
Successfully installed archive-tar-minitar-0.6.1
Fetching: highline-1.6.21.gem (100%)
Successfully installed highline-1.6.21
Fetching: commander-4.2.1.gem (100%)
Successfully installed commander-4.2.1
Fetching: httpclient-2.6.0.1.gem (100%)
Successfully installed httpclient-2.6.0.1
Fetching: open4-1.3.4.gem (100%)
Successfully installed open4-1.3.4
Fetching: rhc-1.38.7.gem (100%)
===========================================================================

 

If this is your first time installing the RHC tools, please run 'rhc setup'

===========================================================================
Successfully installed rhc-1.38.7
Parsing documentation for net-ssh-5.0.2
Installing ri documentation for net-ssh-5.0.2
Parsing documentation for net-ssh-gateway-2.0.0
Installing ri documentation for net-ssh-gateway-2.0.0
Parsing documentation for net-ssh-multi-1.2.1
Installing ri documentation for net-ssh-multi-1.2.1
Parsing documentation for minitar-0.7
Installing ri documentation for minitar-0.7
Parsing documentation for hashie-3.6.0
Installing ri documentation for hashie-3.6.0
Parsing documentation for powerbar-1.0.18
Installing ri documentation for powerbar-1.0.18
Parsing documentation for minitar-cli-0.7
Installing ri documentation for minitar-cli-0.7
Parsing documentation for archive-tar-minitar-0.6.1
Installing ri documentation for archive-tar-minitar-0.6.1
Parsing documentation for highline-1.6.21
Installing ri documentation for highline-1.6.21
Parsing documentation for commander-4.2.1
Installing ri documentation for commander-4.2.1
Parsing documentation for httpclient-2.6.0.1
Installing ri documentation for httpclient-2.6.0.1
Parsing documentation for open4-1.3.4
Installing ri documentation for open4-1.3.4
Parsing documentation for rhc-1.38.7
Installing ri documentation for rhc-1.38.7
Done installing documentation for net-ssh, net-ssh-gateway, net-ssh-multi, minitar, hashie, powerbar, minitar-cli, archive-tar-minitar, highline, commander, httpclient, open4, rhc after 10 seconds
13 gems installed
root@jeremiah:~#

To start with rhc next do:
 

rhc setup
rhc app create my-app diy-0.1


and play with it to install software create services on the Redhat cloud.

 

 

Closure

This are just of the few of the numerous tools available and I definitely understand there is much more to be said on the topic.
If you can remember other tools tor interesting cloud starting up tips about stuff to do on a fresh installed Linux PC to make life easier with Cloud / PaaS / SaaS / DevOps engineer please drop a comment.