SSH from Host VM to Guest VM

aanjhan — Sat, 23 Jan 2010 01:14:27 +0000

I use Fedora for RTEMS development and Ubuntu for my regular academic, leisure tasks. Fedora 12 is a Qemu image which I run using the linux kvm module. It never struck me until recently to just ssh into the guest machine (Fedora 12) from the host (Ubuntu 9.10) and do my RTEMS development work. I had always started the VM and worked inside it. This made my other applications on my host (Ubuntu 9.10) crawl. By default, both KVM as well as Virtual Box have guest to host communication enabled. On the contrary, the host system cannot communicate with your guests. This can be done by making the guest (your Virtual Machines) to listen to one of the host system’s ports.

In KVM this is achieved by adding the “redir” argument to the command while starting the virtual machine;

kvm -hda fedora.img -hdb swap.img -boot c -m -redir tcp:[host-port]::[guest-port]

Here we would like to make the guest port 22 (default ssh port) listen on some host port, say 2222.

kvm -hda fedora.img -hdb swap.img -boot c -m 384 -redir tcp:2222::22

If you are using Virtual Box then follow this tutorial.

Now your guest machine can be accessed via ssh from your host system as you would do for any remote server. E.g.,

ssh -l rtems -p 2222 localhost

In case you need X forwarding, use the -X flag or the -XC flag for X forwarding with compression enabled.

Emacs with tramp mode on my (host) Ubuntu machine is all I now need. A perfect Fedora 12 “remote” development server is setup. I can now do away with all the jazz of GNOME/KDE on the virtual image .

Aanjhan RANGANATHAN's blog » rtems

SSH from Host VM to Guest VM