Hi guys,

I'm having a small problem getting IP forwarding working at home. Here's my setup.

* Wireless adsl router with public dhcp ip of 203.x.x.x as my gateway with internal IP of 192.168.0.1.

* FC5 box using eth1 (wireless) static IP of 192.168.0.5 NAT'd out to the web with gateway of 192.168.0.1. eth0 (ethernet) has a static IP of 192.168.100.1. IP forwarding is enabled.

* RHEL4 box with eth0 (ethernet) configured with static IP of 192.168.100.2. It's connected to the FC5 eth0 port by cross-over cable to get internet access. Gateway is set to 192.168.100.1.

The systems can ping each other no problems and I can even ping my dsl router from the EL4 box but I can't get any internet connection. I've tried static routes and a few other things but it appears my FC5 box isn't forwarding internet data from eth1 to eth0. I have a feeling having my data nat'd to the web might be confusing my boxes a bit.

I can configure my FC5 box to obtain a dhcp ip from my dls router if this is required but I haven't actually done this yet.

Does anyone have any suggestions?


Thanks
Justin

Sounds like you might need to bridge eth0 to eth1 on the FC5 box. Unfortunately I've never done this and have no idea how to but it sounds like that's what you need.

Try these:

Network Bridging
Bridging

Hope that helps

IF the RHEL4 box is getting through with a ping to the adsl router, then forwarding is setup correctly, otherwise the ping would not be able to get back to the host sending it, it sounds it sounds like a DNS issue. Have you pointed the RHEL4 box DNS settings to the FC5 box, and then set the FC5 box DNS settings to the adsl router?

Thanks for the response.

I don't think it's a DNS issue. The only reason I can ping the dsl router is because the FC5 box and my RHEL4 box are in the same IP range (i.e. 192.168.100.0 & 192.168.0.0). If I change eth0 to a different range (e.g. 10.0.0.0) and do the same with my EL4 box, I can't ping the dsl router anymore.

I've tried pinging the ip of certain websites and I get no response so I really don't think it's a dns issue.

Thanks for the bridging info, I'll have a look into that.


Thanks.
Justin

your problems is that dsl router don't know were to route 192.168.100.* ip u need to add static route on dsl router to route 192.168.100.* tru 192.168.0.5 .. and u must have in /ect/sysctrl.conf ip_forward = 1 .. u can test with tcpdump and u will se the icmp on that interface 192.168.0.5 but no response from dsl becuse he don't know were to return pakets an dsl router will use defaul gateway , your real ip gateway

if your dsl router can't use static route u can use on FC5 box iptables
iptables -t nat -A PREROUTING -s 192.168.100.0/24 -j SNAT --to-source 192.168.0.5 and u will get response from router

Why not use DHCP?

You can still have fixed IP addresses by assigning them on the router (I am assuming it can function as a DHCP server). Even with only 2 add'l boxen on your LAN, I think it's slightly easier to admin. everything at the router.

intel_ro maybe right, The adsl router may not know how to get back to the 192.168.100.0 network

Also 192.168.100.0 and 192.168.0.0 are two differnet class C networks

What intel_ro said makes sense to me. That's most likely the problem.

using DHCP will most likely work too. Thanks a lot for your help guys!