Single application through OpenVPN tunnel (Debian Lenny)

"A SOCKS proxy is probably not the best tool for this job. The way I have this set up is:

Run rtorrent as a specific user
Use iptables to forward traffic from that user over the VPN

The question is mainly if you want to run rtorrent as a different user. You are most likely running it inside screen, and screen is not a big fan of su'ing to it's user. It is doable, but an extra thing you will need to figure out.

When researching this exact question for my setup, I found it to be extremely hard to limit the OpenVPN on a process-level. If you can find a way to make it work, I would sure be interested."