I have three machines. One, Machine A, is in China and acts as a PPP server. It has an external IP address that I ppp to from machine B. Machine B is on our 192.168.5 network and has IP 192.168.5.27. It can get out to Internet. When B ppp's to A, A gets 10.0.0.98 and B gets 10.0.0.26. A nd B need to exchange messgages and have the from and to ips be correct (which they are). Now I have machine C, 192.168.5.139. I am trying to avoid having to install PPP on it but it has to communicate with both B and A. B is, of course, no problem. It can be reached via 192.168.5.27 and for some reason I cannot figure out, 10.0.0.26 also works from C to B. To get C to be able to communicate with A I did the following: in C: ip route replace 10.0.0.98 via 192.168.5.27 # Route to 98 through 27 in A: ip route replace 192.168.5.139 via 10.0.0.26 # reverse in B (more complicated): ip forward is set to 1 iptables -t nat -A POSTROUTING -s 192.168.5.139 -o ppp0 -j MASQUERADE This allows me to go to 10.0.0.98 from A and to 192.168.5.139 from C. This works fine for ssh, scp, etc. However, when an IP message is sent from A to C, it appears the return (or FROM) IP address is B (10.0.0.26) not A (192.168.5.139) so when A tries to respond it sends to the wrong location (B). I imagine it is because of the masquerade I can't change all incoming traffic for B to C because A also needs to correspond with B. Is there any iptables command I can use to preserve C's address, but also preserve B's address when the message is from B? I can just install ppp on A but it is a pain in 5.4 and does not always work right. Thanks p.s. and yes B and machines are CentOS 5.4 and A is 4.5 -- To unsubscribe from this list: send the line "unsubscribe linux-ppp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
