How to find out the previous kernel version on CentOS after a reboot

To find out the previous kernel version on CentOS after a reboot, you can use the rpm command to query the package database. Here are the steps:

Open a terminal or SSH session to your CentOS server.

Type the following command to list all installed kernels:

rpm -qa | grep "kernel-[0-9]"

This will output a list of all installed kernel packages.… Read the rest

How to fix /var/log/maillog log file that stuck writing

If the /var/log/maillog file is stuck writing, restarting the rsyslog service may help in resolving the issue.

service rsyslog restart

However, it is important to understand the potential impact of restarting the rsyslog service, as it can affect the logging for other services running on the server.… Read the rest

How to deal with malicious kcached processes

If you find something like below on your server, be sure you’ve detected malicious activity

username 2156075 0.0 0.0 2848 2660 ? Ss Feb09 0:00 [kcached]
username 2156076 0.0 0.0 2852 2660 ? S Feb09 0:01 \_ [kcached]

You can use the lsof command to determine which processes have the files open and whether they are being used for legitimate purposes.… Read the rest

SSL certificates used by the main services on a cPanel server



Here is a brief explanation of each path:

/var/cpanel/ssl/apache_tls/hostname/certificates: This is the directory where the SSL certificates for the Apache web server are stored. The hostname folder contains the certificate files for the specific hostname used for the cPanel account.

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How to add domain as parked/alias using cPanel API whmapi1 one line command?

You can add a domain as a parked/alias using the cPanel API whmapi1 in a single command line using the following syntax:

whmapi1 --output=json --user=USERNAME Park::addparkeddomain domain=DOMAINNAME

Replace USERNAME with your cPanel username and DOMAINNAME with the domain name you want to park/alias.… Read the rest

How to know default webmail client that user uses for email box Horde or Roundcube on a cPanel server

To check the default webmail client that a user uses for their email box on a cPanel server, you can use the following command:

egrep "roundcube|horde" /home/*/.cpanel/nvdata/*_default_webmail_app

It will show a user, email box and default webmail app that set up by the user by default

 … Read the rest

How to change master domain for an account on cPanel server from command line

To change the master domain for an account on a cPanel server from the command line, you can use the cPanel API WHMAPI1. Here are the steps:

– Connect to the server via SSH using your preferred terminal emulator.
– Use the following command to change the master domain for the account:

whmapi1 modifyacct user=USERNAME
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How to generate Self-Signed SSL on cPanel server using command line

Run and put your domain:

read -p "Domain: " domain; username=`/scripts/whoowns $domain`; email=`grep @ /var/cpanel/users/$username |tail -n1 |cut -d '=' -f2|sed -e 's/@/\%40/'`; whmapi1 generatessl domains=$domain countryName=US stateOrProvinceName=Texas localityName=Houston organizationName="The Justice League of GG" emailAddress=$email pass=`openssl rand -base64 15` keysize=2048 skip_certificate=0

Now use WHM to install it

Enjoy!… Read the rest