Date: Mon, 18 Oct 2004 22:05:27 +0800 From: Eugene Grosbein <eugen@grosbein.pp.ru> To: net@freebsd.org Subject: asymmetric NAT Message-ID: <20041018140527.GA441@grosbein.pp.ru>
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Hi! Let's consider a simple scheme with two NAT boxes where packet flow is asymmetric: A----+ | | S ---+ T | | B----+ Here S is a host in the local network and its IP is 192.168.1.1, A and B are both border routers and both do NAT, T is a target server in a public Internet having IP address 1.1.1.1. All links drawn above are WAN and multihop links. Outgoing traffic from S to T flows through A, incoming traffic flows through B. A has 2.2.2.2 for its outer interface, B has 3.3.3.3 for its. A and B both do "static NAT" for S, they translate 192.168.1.1 to 4.4.4.4 (and vise versa). One can try redirect_address 192.168.1.1 4.4.4.4 for natd(8) configuration (and corresponding ipfw rules) to achieve this. AFAIK, libalias and ipnat do not support this configuration currently. I'm trying to patch libalias to support this and have some progress but still cannot make work active mode FTP transfers when S is a client and T is a server. Should this schema work in a theory at least? Eugene Grosbein
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