Configuration dependent on local hostname?


To get access to hosts behind a NAT-router, I have put the following
into my ssh-config:

ProxyCommand none

Host *.my-do.main
ProxyCommand ssh nc -w1 %h 22

This works fine while being outside of the NATted network.

Now I would like to configure a laptop in such a way that it is able
to connect directly to the network as well as from the outside. For
that, I'd like to do something like that:

ProxyCommand none

LocalHost ! *
Host *
ProxyCommand ssh nc -w1 %h 22
LocalHost *

Of course, such a "LocalHost" option does not exist. Maybe there exist
some other way to do this?

BTW: I am using openssh as it comes with opensuse11.1 and ubuntu-8.10

opensus-11.1 $ ssh -V
OpenSSH_5.1p1, OpenSSL 0.9.8h 28 May 2008

ubuntu-8.10 $ ssh -V
OpenSSH_5.1p1 Debian-3ubuntu1, OpenSSL 0.9.8g 19 Oct 2007