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Access Virtualbox Guest machine via SSH


How to Access via ssh a Virtualbox Guest machine.

By default, the network connection in VirtualBox is set to NAT (Network Address Translation), that is every packet coming from the Guest machine is modified so that it seems as it has come from the Host machine. In this way it’s easy for the Guest machine to connect to all the rest of the network (the internet included) but nobody can start a connection with the Guest Machine since it’s hidden behind the Host one.
So, if you are going to test a server service in your Guest machine (i.e. Apache or ssh) you have two choices:
  1. pass to Virtualbox Host network connection;
  2. make virtualbox forward all the packets arriving to a certain port of the Host machine.
This article will describe how to do the latter, in particular in the case of the ssh server. This is an interesting case because it allows you to simulate very well a quite common condition: connecting to a remote Linux headless machine.




We have a Guest Machine with a running ssh server which accepts connections on the TCP port 22. Our goal is to make any packet arriving at a given TCP port (i.e. 2222) of the Host machine, to be forwarded to the TCP port 22 of the Guest Machine.
Fortunately, there is Virtualbox command which permits to do it almost instantly: VBoxManage.
Let <guestname> be the Guest machine name (quote it if it contains spaces), here are the commands that you have to type in the Host machine console:
$ VBoxManage setextradata <guestname> "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/HostPort" 2222
$ VBoxManage setextradata <guestname> "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/GuestPort" 22
$ VBoxManage setextradata <guestname> "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/Protocol" TCP
You can change the string “ssh” with any other you like more. The HostPort must be greater than or equal to 1024 since listening on ports 0-1023 needs root permssions (and Virtualbox usually doesn’t). Instead, GuestPorthas to be equivalent to the one on which the virtualized ssh is listening.
Once you have typed the above commands, you need to close the Guest Machine (a reboot won’t be sufficient), restart it and then connect via ssh with:
$ ssh -l <user> -p 2222 localhost
$ VBoxManage setextradata <guestname> "VBoxInternal/Devices/pcnet/0/LUN#0/Config/http/HostPort" 8080
$ VBoxManage setextradata <guestname> "VBoxInternal/Devices/pcnet/0/LUN#0/Config/http/GuestPort" 80
$ VBoxManage setextradata <guestname> "VBoxInternal/Devices/pcnet/0/LUN#0/Config/http/Protocol" http
The above command will forward port 8080 of host to port 80 of guest. similarly more ports can be forwarded.

For reference : http://mydebian.blogdns.org/?p=148
And this ACTUALLY worked on our systems.
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Comments

  1. Prince MishraNovember 8, 2010 at 4:41 AM

    We have tested the above as Positive on ubuntu Server 9.10 and ubuntu Desktop 9.04, 9.10, 10.04 and 10.10 as guest and Virtualbox-ose running on Linux mint 7 as host as well as Windows 7 as host.

    ReplyDelete
  2. Prince MishraNovember 9, 2010 at 4:36 AM

    A common problem faced by ubuntu desktop users :
    OPENSSH SERVER IS NOT INSTALLED BY DEFAULT.
    install it first, only then try to ssh, else it will show failure.

    ReplyDelete

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