How to change the primary IP addres of a WHM/cPanel server

This is for CentOS/RHEL based servers.
Steps in WHM:

  • Log into WHM and go to Basic cPanel & WHM Setup
  • Change the Primary IP here with the option that says “The IP address (only one address) that will be used for setting up shared IP virtual hosts
  • Note: This might not actually be necessary.

Log in to SSH, and do the following:

  • Edit /etc/sysconfig/network-scripts/ifcfg-eth0
    • Change the IPADDR and GATEWAY lines to match the new IP and Gateway for the new ip

 

  • Edit /etc/sysconfig/network
    • Change the GATEWAY line here if it does not exist in the ifcfg-* file.

 

  • Edit /etc/ips
    • Remove the new primary IP from this file if it is present
    • Add the old primary IP to this file with the format ::

  • Edit /var/cpanel/mainip
    • Replace the old primary IP with the new primary IP

 

  • Edit /etc/hosts
    • Replace the old primary IP with the new one if needed. The hostname’s dns will need to be updated too

 

  • Restart the network service to make the new IP the primary
    • service network restart
    • Note: You’re probably going to be disconnected at this point, and have to log in to ssh using the new primary ip.

 

  • Restart the ipaliases script to bring up the additional IP
    • service ipaliases restart

  • Run ifconfig and make sure all IPs show up correctly

 

  • Update the cpanel license to the new primary IP

 

  • Verify you can still log in to WHM and there is no license warning

 

How to remove Tomcat on cPanel

Want to remove Tomcat from cPanel?

Log-into your server as root using ssh:

Execute the following command to stop the Tomcat process:
# /usr/sbin/stoptomcat

…and to remove the next files, enter:
# rm -f /usr/sbin/starttomcat
# rm -f /usr/sbin/startomcat
# rm -f /usr/sbin/stoptomcat

Finally, remove all mod_jk lines from httpd.conf, including addmodule, loadmodule, and include lines.

Linux server tip: force reboot/shutdown

Forcing reboot

A Linux Server is not Windows XP and if reboot fail you usually still connect by SSH and do something. This commands will show you how to remotely hard reboot machine. Hard reboot mean that shutdown scripts will not run and machine reboot immediately without syncing hard disk drives, shutdown applications etc, it’s more like hitting the reset button.

echo 1 > /proc/sys/kernel/sysrq

echo b > /proc/sysrq-trigger

This commands enable sysrq and after this calls fast reboot. If you want to force shutdown machine try this.

Force shutdown

echo 1 > /proc/sys/kernel/sysrq

echo o > /proc/sysrq-trigger

This came handy, when I had a server that had some IO error and it can no longer read from disk, only few cached binaries into memory kept it running (kernel, SSHD, bash), I could still access the machine via SSH but can no longer do anything, forcing the reboot as mentioned above was my only resort, and it worked like charm…