[techtalk] stupid routing question

[Brian Sweeney]

Hey all-

I've another silly question which I'm sure has a simple answer, yet it has
eluded me, so here goes:

I've got a RHL6.2 box I'm trying to setup as a router.  Here's the
configuration:


---------------------
-Client1            -
-ip:192.168.50.215  -
-netmask:255.255.0.0-
-gateway:192.168.3.1-
---------------------
         |
	   |-------------------Rest of network, including 192.168.1.1
	   |
	 ------
	 |eth0|
-----------------------------
-Router                     -
-eth0 ip:192.168.3.1   	    -
-eth0 netmask:255.255.0.0   -
-eth1 ip:10.15.69.1         -
-eth1 netmask:255.255.255.0 -
-gateway:192.168.1.1        -
-----------------------------
       |eth1|
       ------
         |
	   |
	   |
-----------------------
-Client2              -
-ip:10.15.69.2        -
-netmask:255.255.255.0-
-gateway:10.15.69.1   -
-----------------------

So, I've got a box with 2 NICs, each on a private network.  I've installed
and configured them, checked on "enable routing" in linuxconf, and turned on
"Network Packet Forwarding" in netcfg.  The only thing (I think) that's a
bit odd here is that I've supernetted the 192.168 network, for reasons I
won't go into right now.  As near as I can tell, since both clients are
using the Linux box as there gateway, and it has the appropriate routes with
forwarding enabled, they should be able to hit each other fine.  Instead,
each client can ping either interface on the router, but the clients can't
ping each other.  The router can ping either client as well.

I've tried adding the each of the networks (192.168.0.0 and 10.15.69.0) as
static routes with the router interface ip addresses as gateways.  I've
tried checking and unchecking "enable routing" just for the hell of it.
I've tried Setting the routed daemon to silent mode, and setting it to
export the default route.  I've tried getting rid of the gateway on the
router, so it only knows about the local networks (which I believe may be
the setup reflected below).  I even messed with ip-chains a bit, telling it
to "ipchains -P ACCEPT", in case there was some default denial I was unaware
of.  Everything I've read documentation-wise seems to say that routing is
built-in to the kernel by default and that with the two cards and routing
table I have, there should be no problem; it's "automatic".  Yet, I can't
get it to work.

I did a TCPdump; when I ping from the 10.15.69.2 machine to the
192.168.50.215 machine, I see the request on the eth1 side, but no request
or reply on the eth0 side; a ping the other way yields a similar result.

If anyone can point me in the right direction of good documentation for
something this simple, or has any advice, I'd appreciate it.  Below you can
find an output of my routing table and ifconfig.

Thanks,
Brian

Here's what my routing table and ifconfig output looks like:

Script started on Tue Oct 31 14:04:00 2000
[root at gateway /]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt
Iface
192.168.3.1     0.0.0.0         255.255.255.255 UH        0 0          0
eth0
10.15.69.1      0.0.0.0         255.255.255.255 UH        0 0          0
eth1
10.15.69.0      0.0.0.0         255.255.255.0   U         0 0          0
eth1
192.168.0.0     0.0.0.0         255.255.0.0     U         0 0          0
eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo

[root at gateway /]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
192.168.3.1     *               255.255.255.255 UH    0      0        0 eth0
10.15.69.1      *               255.255.255.255 UH    0      0        0 eth1
10.15.69.0      *               255.255.255.0   U     0      0        0 eth1
192.168.0.0     *               255.255.0.0     U     0      0        0 eth0
127.0.0.0       *               255.0.0.0       U     0      0        0 lo

[root at gateway /]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:50:DA:28:BD:E8
          inet addr:192.168.3.1  Bcast:192.168.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:580 errors:0 dropped:0 overruns:0 frame:0
          TX packets:17 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          Interrupt:10 Base address:0xb800

eth1      Link encap:Ethernet  HWaddr 00:50:DA:83:CE:D7
          inet addr:10.15.69.1  Bcast:10.15.69.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:59 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          Interrupt:11 Base address:0xb400

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:3924  Metric:1
          RX packets:24 errors:0 dropped:0 overruns:0 frame:0
          TX packets:24 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
-----------------------------
Brian J. Sweeney
Systems Admin, imagedog.com
email: bsweeney at imagedog.com