Hi misc, For my own education, I'm writing in C a PPTP proxy for pf-driven NAT-boxes, based on libevent. A PPTP session is made of a TCP control connection and a GRE tunnel. I've got no trouble handling the control connection, but I don't know how to handle GRE packets. Actually, I bind a first raw socket on 127.0.0.1, with protocol=IPPROTO_GRE, rdr'ing with pf all outgoing GRE packet from lan here. I can read GRE packets from this socket, great. The idea is to copy these packets on a second gre raw socket, binded on the wan interface ip address. I encounter these problems : * How can I find my wan interface ip address ? * How can I handle his dynamic nature ? (this is a pppoe(4) interface) * How can I handle multiple wan ip address ?
I though it should be possible to have only 1 "big" socket for the whole proxy, listening on 0.0.0.0 (is that equivalent to INADDR_ANY ?). Reading GRE packets from clients should be the same way as before, but what about writing GRE packets to servers ? Which source IP will be choosen for these packet ? I feel that this design is bad but I lack some raw socket background. I'd like the advice of sockets guru :) I've read this and didn't find something usefull : UNIX Socket FAQ : http://www.developerweb.net/forum/index.php Best regards, Bruno.
