Sent to wrong one (@netfilter.org), sorry :-) ---------- Forwarded message ---------- Date: Tue, 29 Aug 2006 10:07:48 +0200 (MEST) From: Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx> To: Innocenti Maresin <qq@xxxxxxxx> Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>, netfilter@xxxxxxxxxxxxx Subject: Re: Q: remapping IP addresses for inbound and outbound traffic Hi, >The software of this box needs to connect all hosts in both networks, and >also to receive inbound TCP connections. The evident way is to "remap" >overlapping IPv4 area of one network to some "place" not used neither in it >nor in other. This means that, when we receive a packet from remapped area, >the kernel should replace the source IP to an "internal representaion". >Versa, sending something to "internally represented" IP the kernel should >replace such IP by its external value. I clarify these terms so carefully >because in news:comp.os.linux.networking some people state that I "use terms >in strange ways" :) > >The question is: how to do it? Please, don't say quicky "iproute2" and >"RTFM". Iproute2 can do such things when *forwarding* packets. I need no >forwarding at all, no *connection* between 2 networks. I need only to >*serve* both networks, such that some "external" IPs need to be replaced by >internally used IP and versa. All this at one Linux box. No forwarding >traffic. Only inbound and outbound. I am working on a small module doing something like that, changing IP addresses before the NAT code sees them, in mangle. http://jengelh.hopto.org/f/xt_MAP-v0.tar.bz2 I still cannot get outgoing mangled packets (see command below) to reach their destination: iptables -t mangle -A POSTROUTING -d 134.76.13.21 -j MAP \ --map-dest 134.76.13.28 ping and TCP packets seem to leave the box (tcpdump), but there are no responses (neither negative responses). The destination box's tcpdump also shows nothing. netfilter list, am I missing something like recalculating IP checksums? Jan Engelhardt --
