Configuring a transparent proxy on a client machine ONLY instead of a server machine.

clinux_rulz · 05-29-2006, 10:40 AM

Hi all,

I've been trying to find for awhile now how to configure a client machine to connect to the internet through a proxy on a server machine without configuring any applications on the client machine for proxy, by using the iptables command on the client machine.

All documentation i've googled on transparent proxying have been to do with setting up a transparent proxy either on the server machine or a machine between the server machine and the client machine.

The reason why I would like to set the client machine up this way, is that at uni my client machine is connects to the internet via a proxy on the server machine, I am unable to touch the server machine, and my client machine has commands that need the internet (most of which use port 80) and can not be configured for proxy.

I was kinda hoping I could do something like this ...

iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 1.2.3.4:8080

where 1.2.3.4 is the ip of the proxy server.
It does not work tho.

Cheers.

Clinton.

clinux_rulz · 05-31-2006, 02:53 AM

Ok I think I worked out a part of it. I need to use the OUTPUT channel in the "nat" table, from my client machine.

The server uses a squid proxy.

Code:

iptables -t nat -A OUTPUT -p tcp --dport 80 -j DNAT --to-destination 1.2.3.4:8080

The only problem now is that it is a Authenticated proxy. I need to supply a username and password somehow.

Any ideas?