> Roman,
>
> I'm not quite clear on your configuration. What sort of device is the
> internet-proxy? Is it a NAT router, or something else? Are all three
> devices in the same subnet? It sounds like you're either trying to work
> around not having a hub, or not having a NAT device.

Thanks for your answer.

Here the whole configuration: (imagine it as a complicated line of different 
connections through the entire house...)

PC1 (the proxy-running-pc) is running windows and a proxy software for the 
internals of my skydsl connection.

[PC1 and Router1 are connected via wired-lan]

Router1 is acting as a wlan-lan bridge (but without any direct internet 
functions..).

[Router1 and PC2 are connected via wireless-lan]

PC2 (the internet-pc) is running gentoo and has a wireless and a wired-lan 
connection.

[PC2 and PC3 are connected via wired-lan]

PC3 (the non-internet-pc) is running genoo and only has a wired-lan 
connection.

All I need is (ping like) access to PC1 to use the internet connection. 
(Usually adding the http_proxy environment variable or something to PC1's 
IP-address.)

PC2 has Router1 set as the default gateway and can ping PC1 hence.

PC3 has set PC2 as the default gateway, but cannot ping anything else than 
PC2. (...which is directly connected anyway...)

I think NAT isn't what I'm looking for, I just need ping access to _one_ 
specific ip, so, some static routes should do the job.

I hope that clarifies my situation.

Thanks for your help so far.