Is your LAN off of eth1 a DMZ with some kind of publicly availble server that you want protected? You could put it in another private address range, say 192.168.10.0/24 and then use SNAT and DNAT to disguise it from the world. Or you could split up a.b.c.0/24 into two sets of a.b.c.0/25 and a.b.c.128/25 if you need real routable IP addresses on this DMZ system. You will want the same subnet mask on your a.b.c.<whatevers> unless you plan to subnet it even more when you get farther inside. Remember, the mask determines which bits are the network and which bits are the host. So it needs to be consistent all the way through. - Greg -----Original Message----- From: David Koski [mailto:david@kosmosisland.com] Sent: Monday, January 28, 2002 3:07 PM To: LARTC@mailman.ds9a.nl Subject: [LARTC] routing network through bastian host Hello, This seems to be a common problem but AFAIK, without a common solution. The network map is as follows: T1 to ISP | | /30 net | +----------------+ | cisco router | +----------------+ | FastEthernet0/0 | a.b.c.1/24 | (possible switch/hub here in future) | | a.b.c.2/24 | eth0 +----------------+ | | | eth1 |---a.b.c.3/24-public-net-----> lan | linux box | | eth2 |---192.168.1.0/24-private-net---> lan | | +----------------+ Of course the above does not work as eth0 and eth1 are on the same subnet. So far, I can see two possible solutions: 1. reassign the cisco to linux net to a private point to point /30 net. I have tried with limited success. 2. reassign the cisco to linux net to a.b.c.1/29 (cisco) and a.b.c.2/29 (linux box). This would give me a block of 8 between cisco and linux and would enable me to add a switch/hub between to feed another host for backup mail relay and dns server. Questions: 1. Does a different subnet mask define a different subnet? Will the "two nics same net" conflict be resolved by applying a longer mask to one subnet? 2. What is required to route through the linux box in "solution" 2 above? Is this a case of "more specific, preferred route" applied? 3. Any relevant RFC's would be helpful. 4. Of course, ANY suggestions welcome. TIA, David Koski david@KosmosIsland.com _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://ds9a.nl/lartc/
