*BSD News Article 76242


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From: iverson@cisco.com (Tim Iverson)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: NAT / IP Masquerading
Date: 16 Aug 1996 02:28:45 GMT
Organization: cisco
Lines: 21
Message-ID: <4v0mct$75t@cronkite.cisco.com>
References: <320F7133.41A5@ase.telerate.com> <32127C57.7B4D268B@lambert.org>
NNTP-Posting-Host: rottweiler.cisco.com

In article <32127C57.7B4D268B@lambert.org>,
Terry Lambert  <terry@lambert.org> wrote:
|Jim King wrote:
|] I have an application where I'm thinking of using a FreeBSD box
|] as a router to do NAT.  This is very straightforward, I just
...
|] I've tried running IP Filter on FreeBSD 2.1.5-RELEASE.  It sometimes
|] works, but today I'm getting a kernel panic every time I try to ping

It works for me on 215R, but then I've hacked it bit.

|I believe that ICMP datagrams would not normally be forwarded by
|any type of "masquerading"... you would need real proxy services
|(seee RFC-1919 where it talks about "...Transparent IP Proxies...").

Many NATs also do quite a bit of proxy work, usually ICMP and FTP as a
minimum -- after all, a completely blind NAT isn't terribly useful.  I can
ftp, ping, and traceroute across my IP-Filter NAT'd network.

- Tim Iverson
  iverson@lionheart.com