Date: Sat, 25 Oct 2003 21:04:23 +0200 From: Nils Vogels <nivo+sender+8eb026@yuckfou.org> To: freebsd-net@freebsd.org Subject: Reverse IP NAT to secondary IP address Message-ID: <3F9AC937.4070200@yuckfou.org>
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Hi there! I'm trying to solve a situation that I have with a device which needs SNMP polling, but is not normally reachable to the outside world, because it cannot install a default gateway. In short, a situation scetch: SNMP-server (192.168.2.2/24) ----------- +------------+ +-------------+ | | WWW |--------------------| Gateway | --------------+ +------------+ +-------------+ | 192.168.0.2/24 192.168.0.1 IP: 195.x.x.x.x \-----> Internet (0.0.0.0/0) (rl0) Alias: 192.168.2.1 (ed0) Now what I am trying to do is get statistics from the SNMP-server into the WWW box, but I am stuck on the following: WWW is a FreeBSD-4.8 box. Gateway is a FreeBSD-4.8 box with IP Filter Since the SNMP-server does not have a default route, the traffic needs to originate from an IP address within the same subnet as the Gateway. To that end, I have added an alias IP of 192.168.2.1 to the gateway. When I run an snmpwalk from the gateway all goes fine. Since the traffic is coming from WWW and heading through the Gateway, which does not bridge, I have to perform some form of NATting in the gateway. I've been searching and attempting various redirects and map entries, and am now stuck at: map rl0 from 192.168.0.0/24 to 192.168.2.0/24 port = 161 -> 192.168.2.1/32 I think I'm close .. can someone give me the final hint ? ;-) Thanks, Nils.
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