If this message is inappropriate in this forum I apologize.
I am trying to create a 16 node (netmask 255.255.240.0) subnet with a
linux box as a router.
I have a i586 running the linux kernel 2.4.13. My distribution is
Redhat 7.0. I have two EtherExpressPro cards in my machine. I have had
the same difficulty with a 2.4.5 and a 2.2.x kernel.
Throughout the scattered Linux networking literature it is often
flippantly remarked that turning on interface forwarding is a snap:
cat > /proc/sys/net/ipv4/ip_forward
"1"
is supposed to do the trick. Unfortunately, it does not do the desired
trick.
When I turn on forwarding as I have above, I can ping the router
(133.27.179.224 or 133.27.16.221) from a host (133.27.179.226) on the
eth1 subnet. However, pings are never returned to this subnet host
(133.27.179.226) if they are bound for hosts on the eth0 network
(133.27.16.x) or beyond. Furthermore, pings from the linux router
(133.27.179.224 and 133.27.16.221) to the subnet host (133.27.179.226)
are never returned.
Is there something obvious that I am missing? Is there something arcane
I am missing?
Here is my configuration:
% ifconfig
eth0 Link encap:Ethernet HWaddr 00:02:B3:3D:59:14
inet addr:133.27.16.221 Bcast:133.27.19.255
Mask:255.255.252.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:17048 errors:0 dropped:0 overruns:0 frame:0
TX packets:46 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:10 Base address:0x2000
eth1 Link encap:Ethernet HWaddr 00:02:B3:3D:44:2A
inet addr:133.27.179.224 Bcast:133.27.179.239
Mask:255.255.255.240
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:9 Base address:0x4000
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:6 errors:0 dropped:0 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
% route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
133.27.179.224 0.0.0.0 255.255.255.240 U 0 0 0
eth1
133.27.16.0 0.0.0.0 255.255.252.0 U 0 0 0
eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0
lo
0.0.0.0 133.27.16.1 0.0.0.0 UG 0 0 0
eth0
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