On Tue, 06 Nov 2007, in the Usenet newsgroup comp.os.linux.setup, in article <1194359819.743764.97060@50g2000hsm.googlegroups.com>, George wrote: NOTE: Posting from groups.google.com (or some web-forums) dramatically reduces the chance of your post being seen. Find a real news server. >Here is a textual image of the network: > >RH1 (eth0:10.0.0.2) ->cabled to eth1 on RH2 >RH2 (eth0:149.8.6.114, eth1:10.0.0.1) -> eth0 cabled to "the >world" (default GW 149.8.6.1) >The netmask for everything is 255.255.255.254 ERROR - netmask for RH2:eth0 can not be 255.255.255.254 - must be a minimum of 255.255.255.128 in order to talk to the gateway. ERROR - netmask of 255.255.255.254 not usable on 10.0.0.[12]. The mask allows for NO usable addresses (there would be two, the so-called network which would be the _even_ address - 10.0.0.0 or 10.0.0.2 - and the _odd_ address would be the 'broadcast', either 10.0.0.1 or 10.0.0.3. Mask must be a minimum of 255.255.255.252 which would provide 10.0.0.0 network 10.0.0.1 host 10.0.0.2 host 10.0.0.3 broadcast >I want RH1 to ping 149.8.6.1 i,e, that Gateway. >RH1 can now ping 149.8.6.114 and 10.0.0.1, but I can't get it to see >149.8.6.1. >RH2 can ping 10.0.0.2, localhost, 10.0.0.1, and 149.8.6.1 and beyond. Two problems - IP forwarding you mentioned below, but the "other" hosts have to know how to reply - they must have a route to 10.0.0.2 using 149.8.6.114 as the gateway. OTHER SOLUTION is to set 'RH2' to masquerade for RH1. See the HOWTOs: 708351 Nov 14 2005 IP-Masquerade-HOWTO 17605 Jul 21 2004 Masquerading-Simple-HOWTO 287057 Jul 23 2002 Security-Quickstart-Redhat-HOWTO for details. >If have tried all sorts of route add -net combinations on both RH1 >and RH2. >I've messed with various setting in /etc/sysconfig/network as well as >/etc/sysconfig/networking/devices/ifcfg-eth0 or 1. I messed with the >ip forwarding settings in /etc/sysctl.conf for example. I read through >lots threads in the group and many I thought were right on the mark. >But I'm missing something or my understanding of this possibility is >flawed. Yeah - 'comp.os.linux.networking' might be a more appropriate newsgroup but the clues are in those howtos. >I thought my understanding of the output of netstat -nr was sound, >but maybe I am reading it wrong or maybe I'm just missing something. I suspect that the gateway has no idea how to respond to your pings. The solution is to either tell the gateway (and all other hosts you may wish to talk to) how to reach 10.0.0.2 using 149.8.6.114 as a router, OR set up RH2 to masquerade for RH1. The later is probably more appropriate - but your details are thin. Old guy