configuring redhat 9 as a router between 2 networks

[menonrr at adelphia.net]

I am a fairly new Lunux user and to the redhat website.

I could not find a way to append additional details to my earlier meesage. Hence I am reproducing the entire problem.

I am trying to setup a test netork as follows:

172.16.4.0 ---> | eth0_inside (172.16.4.2)-- Redhat 9 Box -- eth1_toRouter (172.16.3.10)| ---> router (172.16.3.4)

eth0_inside IP is 172.16.4.2. The default gateway has the eth1_toRouter's IP 172.16.3.10.

eth1_toRouter IP is 172.16.3.10 and its default gateway is the
router's IP 172.16.3.4.

I edited the sysctl.conf file in /etc to put a value of '1' to
net.ipv4.ip_forward. I rebooted the machine.

Result:

I can ping both interfaces, the router, and the inside hosts
from the linux box.

The hosts can ping only up to eth1_toRouter (172.16.3.10). Not
beyond that.

Your help would be greatly appreciated.

Some details:

Thank You for the reply. I just outputted all I could think of:-

The output:

[root at localhost log]# cat /proc/sys/net/ipv4/ip_forward
1

[root at localhost log]# netstat -nr
Kernel IP routing table
Destination Gateway   Genmask Flags MSS Window irtt I face
172.16.4.0  0.0.0.0   255.255.255.0 U    0      0   0 eth0
172.16.3.0  0.0.0.0   255.255.255.0 U    0      0   0 eth1
169.254.0.0 0.0.0.0   255.255.0.0   U    0      0   0 eth1
127.0.0.0   0.0.0.0   255.0.0.0     U    0      0   0 lo
0.0.0.0     172.16.3.4 0.0.0.0      UG   0      0   0 eth1

[root at localhost log]# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:60:97:DF:8A:82
inet addr:172.16.4.2 Bcast:172.16.4.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:246 errors:0 dropped:0 overruns:0 frame:0
TX packets:22 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:28775 (28.1 Kb) TX bytes:1488 (1.4 Kb)
Interrupt:11 Base address:0xdcc0

eth1 Link encap:Ethernet HWaddr 00:06:5B:B5:86:A9
inet addr:172.16.3.10 Bcast:172.16.3.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:505 errors:0 dropped:0 overruns:0 frame:0
TX packets:174 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:45158 (44.0 Kb) TX bytes:18754 (18.3 Kb)
Interrupt:11 Base address:0xdc00

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:15309 errors:0 dropped:0 overruns:0 frame:0
TX packets:15309 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1044830 (1020.3 Kb) TX bytes:1044830 (1020.3 Kb)