rubysecurity.org

Anecdotes from a Linux Systems Administrator. /root

Home About Books Blog Portfolio Archive
10 November 2018

Accessing KVM Guest Using Virtual Serial Console

by Alpha01

For the longest time, after creating my KVM guest virtual machines, I’ve only used virt-manager afterwards to do any sort of remote non-direct ssh connection. It wasn’t until now that I finally decided to start using the serial console feature of KVM, and I have to say, I kind of regret procrastinating on this, because this feature is really convenient.

Enabling serial console access to a guest VM is a relatively easy process. In CentOS, it’s simply a matter of adding the following kernel parameter to GRUB_CMDLINE_LINUX in /etc/default/grub

console=ttyS0

After adding the console kernel parameter with the value of our virtual console’s device block file. Then we have to build new a grub menu and reboot:

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

Afterwards from the host system, you should be able to virsh console onto the guest VM.

The only caveat with connecting to a guest using the virtual serial console is existing the console. In my case, the way to log off the console connection was using Ctrl+5 keyboard keys. This disconnection quirk reminded me of the good old days when I actually worked on physical servers and used IPMI’s serial over network feature and it’s associated unique key combination to properly close the serial connection.

Resources

Tags: [ kvm ]