I recently purchased a VPS and am wanting to use it as a VPN server. However, it has bandwidth limitations. So, I figured since I already have a local Squid proxy caching things for me, I could have users connect to the proxy and the proxy connect to the VPN. Then when someone hits the web, Squid will serve it from cache if available and, if not, it will use the VPN to download it.

My issue is, I have no idea how to set this up :p - Essentially I want Machine -> Squid -> VPN.

My VPN is running on Ubuntu Server with pptpd. Squid is running on a local Arch Linux box. Squid and the VPN are both working perfectly independently. Any help on how to have Squid push traffic through the VPN would be greatly appreciated!

Also: I don't actually want to use the VPN for all traffic. Otherwise, I'd just connect my router to the VPN and be happy. I only want to use it for web traffic from specific machines on the network.