SSH directly "through" another server [duplicate]

Possible Duplicate:
How to configure a shortcut for an SSH connection through a SSH tunnel

Multiple networks I can connect to have the following set up. There is a single node that can be accessed with ssh from the internet, and from there you can ssh to the inside network.

Is there a way, that on my ubuntu box (no sudo rights), I somehow can configure that the command ssh internal.host is first setting up an connection to external.host and from there to internal.host? In the ideal situation it would be something very transparent, so that I even would be able to do scp myfile internal.host:

All authentication is done with certificates.

Btw. I am aware of ssh tunnels. I'm only searching something more transparent, I don't want to have to always manually open an ssh tunnel to reach a host.

edit your .ssh/config file and add:

Host internal.host
   User abc
   ForwardX11 yes
   ProxyCommand ssh -qxT external.host netcat internal-ip-of.internal.host 22