On Sat, Mar 23, 2013 at 08:30:10PM +0800, Hexchain Tong wrote: > On Sat, Mar 23, 2013 at 2:39 PM, Bill Sun <cap.sensitive@xxxxxxxxx> wrote: > > > > I'm thinking about running a http server that handles all the > > authentication for Server 2 (such as dante?), then forward all packets > > to that server (running in Server 1). But I don't know how to write > > corresponding iptables rules. So how to write such rules? > > You need to setup another proxy on Server 1. Take squid for example, > in squid.conf, set upstream server using cache_peer and authentication > parameters (please refer to squid manual because I don't know how to > do it :-P ), and set a port that handles intercepted traffic (or it > won't work!): > > http_port <local_squid_port> intercept > > and insert the following iptables rule: > > iptables -t nat -A PREROUTING -s <ip_addr_for_pptp> -p tcp --dport 80 > -j REDIRECT --to-port <local_squid_port> Great! It works! But I need to add an additional iptables rule: iptables -t nat -A POSTROUTING -j ACCEPT Regards.