Category: CentOS/RedHat

How to convert from CentOS 8 to CentOS 8 Stream

Here are the steps needed to convert from CentOS 8 to CentOS 8 Stream.

First backup anything important, the conversion process is fairly simple and smooth with no issues usually but just in case make backups of important stuff if anything goes wrong.

Second step is to install all pending updates on current CentOS 8 installation.

Update to latest version of packages with following command:

dnf update

After updates are installed reboot the machine to make sure latest kernel version is loaded and that everything is working normally with latest package versions before migrating to CentOS 8 Stream:

reboot

After the machine is back up install centos-release-stream package with following command

dnf install centos-release-stream
dnf install centos-release-stream

After centos-release-stream has been installed swap repos from CentOS Linux 8 repos to CentOS Stream 8 repos with following command

dnf swap centos-linux-repos centos-stream-repo
dnf swap centos-linux-repos centos-stream-repo

After repos have been swapped check if correct repos are listed in dnf with following command

dnf repolist

You should see CentOS Stream 8 repos listed now instead of CentOS Linux 8 repos that were there before.

dnf repolist before swap
dnf repolist after swap has been made

When CentOS 8 Stream repos have been set sync all installed packages with CentOS Stream versions using following command:

dnf distro-sync

After packages have been synced you can use cat /etc/redhat-release or hostnamectl command to check and confirm that you are now running CentOS Stream 8 OS.

This is an output of hostnamectl command before the sync:

hostnamectl 
   Static hostname: server0
         Icon name: computer-vm
           Chassis: vm
        Machine ID: ba45dac81f4e4f6f9c9bb2657914c81e
           Boot ID: e36de8bd66f1467983104acd47defac0
    Virtualization: kvm
  Operating System: CentOS Linux 8
       CPE OS Name: cpe:/o:centos:centos:8
            Kernel: Linux 4.18.0-348.2.1.el8_5.x86_64
      Architecture: x86-64

This is an output of hostnamectl command after dnf sync command has been run:

hostnamectl 
   Static hostname: server0
         Icon name: computer-vm
           Chassis: vm
        Machine ID: ba45dac81f4e4f6f9c9bb2657914c81e
           Boot ID: 526a47bb15b4420db4cc3cf364af9555
    Virtualization: kvm
  Operating System: CentOS Stream 8
       CPE OS Name: cpe:/o:centos:centos:8
            Kernel: Linux 4.18.0-348.7.1.el8_5.x86_64
      Architecture: x86-64

Reboot the server and check for any possible issues.

Install OpenLiteSpeed with PHP 8.1

These are the steps to install OpenLiteSpeed with lsphp81 on CentOS replacements like AlmaLinux 8 or RockyLinux 8.

First add LiteSpeed repositories for AlmaLinux 8 & CentOS 8 with following command:

rpm -Uvh http://rpms.litespeedtech.com/centos/litespeed-repo-1.1-1.el8.noarch.rpm

After you have installed the rpm package you will get /etc/yum.repos.d/litespeed.repo repo file which you will need to edit in order to avoid getting the following error when installing or updating packages with yum/dnf.

Invalid configuration value: failovermethod=priority in /etc/yum.repos.d/litespeed.repo; Configuration: OptionBinding with id "failovermethod" does not exist

This will happen because the ‘failovermethod’ option is not supported by dnf which comes with RHEL 8.

Comment out that line from /etc/yum.repos.d/litespeed.repo with following command:

sed -i 's/failovermethod=priority/#failovermethod=priority/' /etc/yum.repos.d/litespeed.repo

Install OpenLiteSpeed with following command:

dnf install openlitespeed

After you have installed OpenLiteSpeed install Extra Packages for Enterprise Linux (EPEL) repository with following command:

dnf install epel-release

After that install PHP 8.1 for OpenLiteSpeed with most commonly used packages:

dnf install lsphp81 lsphp81-common lsphp81-mysqlnd lsphp81-gd lsphp81-process lsphp81-mbstring lsphp81-xml lsphp81-opcache

If you wish to install a different version of PHP just replace lsphp81 with lsphp80 for PHP 8.0 or lsphp74 for PHP 7.4 and similar.

By default OpenLiteSpeed will run on port 8088 and its WebAdmin Console will run on port 7080.

OpenLiteSpeed WebAdmin Console will have default username admin but the admin password will be randomly generated.

If you want to reset OpenLiteSpeed admin password you can run /usr/local/lsws/admin/misc/admpass.sh script which can be used to set admin password to desired value.

If you run the script it will use username admin if you don’t specify any and will then ask you to input a new password for OpenLiteSpeed administration web interface.

/usr/local/lsws/admin/misc/admpass.sh 

Please specify the user name of administrator.
This is the user name required to login the administration Web interface.

User name [admin]: 

Please specify the administrator's password.
This is the password required to login the administration Web interface.

Password: 
Retype password: 
Administrator's username/password is updated successfully!

Reset SSH, and find SSH port on cPanel/WHM server

If you lock yourself out of SSH access to your cPanel server or if you do not know on which port your SSH server is running there are several ways you can gain back SSH access to your server.

Flush iptables

If your  IP got locked out in iptables you can use one of cPanel autofixer scripts to flush all iptables chains so your IP can reach SSH on your server again.

Script can be called by adding “scripts2/doautofixer?autofix=iptablesflush” to the end of the WHM url in your browser, and should look something like this:

https://server.domain.tld:2087/cpsess1290981925/scripts2/doautofixer?autofix=iptablesflush

flushing iptables

Reset SSH

If you SSH server is not accessible because of a broken configuration or anything else and is not restarting properly through Home »Restart Services »SSH Server (OpenSSH) in WHM you can try starting safesshrestart script which will kill any running instance of sshd and start a new process on port 22, or if that port is taken on first available port after that, like port 23.

Script can be started by adding “scripts2/doautofixer?autofix=safesshrestart” to the end of your WHM url and should look something like this:

https://server.domain.tld:2087/cpsess1290981925/scripts2/doautofixer?autofix=safesshrestart

Pay attention to the output in WHM when script runs, it will say on which port was SSH started.

safesshrestart

Find out your SSH port

If you are not sure on which port is your SSH server running you can find that out on two ways.

You can use the Restart Services part of WHM and restart SSH by going to Home »Restart Services »SSH Server (OpenSSH) in WHM and watching the output in WHM after you restart SSH, it will say on which port is SSH listening.

Other option is to use an API call to show the port.
You can do that by adding “xml-api/cpanel?user=cpanel&cpanel_xmlapi_apiversion=1&cpanel_xmlapi_module=SSH&cpanel_xmlapi_func=getport” to the end of your WHM url which should look something like this:

https://server.domain.tld:2087/cpsess1290981925/xml-api/cpanel?user=cpanel&cpanel_xmlapi_apiversion=1&cpanel_xmlapi_module=SSH&cpanel_xmlapi_func=getport

You can find out more about WHM autofixers on following link:

https://documentation.cpanel.net/display/ALD/WHM+FAQ#WHMFAQ-WhatistheWHMAutofixer?

Full list of all autofixers can be found here:

http://httpupdate.cpanel.net/autofixer/

VMware rename CentOS 7 NIC names

CentOS 7 virtual machines on VMware will by default use predictable network device naming for network interfaces on the machine, causing their names to be in enoXXXXXXXX format.

This will cause issues when adding 10 or more additional IPs in WHM, as network interface name will be longer than the 15 characters.

Maximum length supported for network interface name on cPanel servers is 15 characters.

When starting ipaliases service, only first 9 additional IPs will be added, and for rest of the IPs error “RTNETLINK answers: Numerical result out of range” will be shown, and IPs will not be shown in ip addr, or ifconfig output.

[root@server ~]# /scripts/restartsrv_ipaliases
Waiting for "ipaliases" to stop ...finished.
Waiting for "ipaliases" to start ...finished.
Service Status
Startup Log
 Oct 03 20:29:20 server.example.com ipaliases[233833]: [FAILED]
 Oct 03 20:29:20 server.example.com ipaliases[233833]: Bringing up eno33559296:cp14 RTNETLINK answers: Numerical
result out of range
 Oct 03 20:29:20 server.example.com ipaliases[233833]: [FAILED]
 Oct 03 20:29:20 server.example.com ipaliases[233833]: Routing 204.93.248.69 RTNETLINK answers: Invalid argument
 Oct 03 20:29:20 server.example.com ipaliases[233833]: [FAILED]
 Oct 03 20:29:20 server.example.com ipaliases[233833]: Bringing up eno33559296:cp15 RTNETLINK answers: Numerical
result out of range
 Oct 03 20:29:20 server.example.com ipaliases[233833]: [FAILED]
 Oct 03 20:29:20 server.example.com ipaliases[233833]: Routing 204.93.248.70 RTNETLINK answers: Invalid argument
 Oct 03 20:29:20 server.example.com ipaliases[233833]: [FAILED]
 Oct 03 20:29:20 server.example.com systemd[1]: Started cPanel IP aliases service.
Log Messages
 Oct 3 20:29:20 server ipaliases: [FAILED]
 Oct 3 20:29:20 server ipaliases: Routing x.x.x.x RTNETLINK answers: Invalid argument
 Oct 3 20:29:20 server ipaliases: [FAILED]
 Oct 3 20:29:20 server ipaliases: Bringing up eno33559296:cp15 RTNETLINK answers: Numerical result out of range

To resolve the issues, network devices can be renamed back to old ethX type of naming.

To rename network devices to old names following steps are needed.

  1. Edit /etc/sysconfig/grub
  2. Update GRUB configuration with new kernel parameters
  3. Rename network files
  4. Edit renamed network files
  5. Reboot the server

To rename devices do the following

Edit /etc/sysconfig/grub

Find a line containing “GRUB_CMDLINE_LINUX”, and append “net.ifnames=0 biosdevname=0“ on the line.

File should look something like this.

[root@server ~]# cat /etc/sysconfig/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=myvg/rootvol rhgb quiet net.ifnames=0 biosdevname=0"
GRUB_DISABLE_RECOVERY="true"

Update GRUB configuration with new kernel parameters, with following command:

grub2-mkconfig -o /boot/grub2/grub.cfg

Rename enoXXXXXXXX network files of all interfaces to ethX network file.

For example:

mv /etc/sysconfig/network-scripts/ifcfg-eno16777984 /etc/sysconfig/network-scripts/ifcfg-eth0
mv /etc/sysconfig/network-scripts/ifcfg-eno33557248 /etc/sysconfig/network-scripts/ifcfg-eth1

This will rename file ifcfg-eno16777984, to ifcfg-eth0, renaming interface eno16777984 to eth0, and will rename file ifcfg-eno33557248, to ifcfg-eth1, renaming interface eno33557248, to eth1.

Edit new ethX network files.

Replace value of both NAME and DEVICE field with new ethX names.

File should look something like this.

[root@server ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
BOOTPROTO=static
NAME=eth0
UUID=b02f4abf-f6da-4ad4-b800-4abf4fe1d50d
DEVICE=eth0
ONBOOT=yes
NM_CONTROLLED=yes
IPADDR=x.x.x.x
NETMASK=255.255.255.0
GATEWAY=x.x.x.1

Reboot the server, and you should now see network interfaces using old CentOS 6 style names.

Additional changes for cPanel servers

Change public network interface in Basic cPanel & WHM Setup.

Go to Home »Server Configuration »Basic cPanel & WHM Setup and change public interface from old enoXXXXXXXX to new ethX name.

Change public interface to new name
Change public interface to new name

Restart ipaliases service with /scripts/restartsrv_ipaliases.

Reset root password on CentOS 6 machine

If you have forgotten root user password on your CentOS 6 machine, you can reset the password to new value, without knowing the old one, by booting the machine to single user mode, and resetting the password with passwd command.

Boot to single user mode

During the CentOS boot process, you will be presented with a countdown before CentOS boot process actually begins to load the OS.

Press any key to enter the GNU GRUB menu.

CentOS 6 boot countdown
CentOS boot countdown

On the GNU GRUB menu highlight the kernel you want to boot, and press ‘e’ key to edit the kernel commands before booting.

CentOS 6 kernel select
CentOS 6 kernel select

Once you have entered the kernel edit mode, find the line beginning with kernel, and highlight it, and press ‘e’ key to edit it.

Edit kernel line
Edit kernel line

On the end of the line add the word ‘single’, with white space before ‘single’, and press ENTER to accept the change.

Add single to then end of the kernel line
Add single to then end of the kernel line

Boot the machine with the edited kernel argument, and you will be logged in as root in single user mode.

Now just issue passwd command, and enter the new password two times, when asked.

Change password with passwd command
Change password with passwd command

Once you have changed the password, reboot the machine, and log to it with your new root password.