topic Help with 2 NIC in Operating System - Linux

Help with 2 NIC

Low Han Ming — Wed, 28 Mar 2001 10:36:31 GMT

Hi,

I've a RH 6.2 with 2 3Com NIC.
I've installed 1 nic under subnet 143.186.138.x and the other under 192.168.0.x

My problem is that I can ping anywhere in the 143.186.138.x,but in the 192.168.0.x, I can only ping to myself.

However, I'm sorry that I'm rather new and couldn't really figure out what's wrong.

Can anyone kindly point out my mistake.

I'm sorry that the attach route table may be mis-align. I'd be glad if I can send a mail to anyone who like to take a look.

Thanks.

Han Ming

###############################################My ifconfig is :-
eth0 Link encap:Ethernet HWaddr 00:10:5A:83:ED:12
inet addr:143.186.138.240 Bcast:143.186.138.255
Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:15490590 errors:0 dropped:0 overruns:0 frame:0
TX packets:25147189 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:16 Base address:0xcc00

eth1 Link encap:Ethernet HWaddr 00:50:DA:B6:D7:D0
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:2045 frame:0
TX packets:0 errors:3712 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:16 Base address:0xc800

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:5639 errors:0 dropped:0 overruns:0 frame:0
TX packets:5639 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
###############################################

##############################################################################

My route table is:-
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
slacker00 * 255.255.255.255 UH 0 0 0
eth1
slacker00 * 255.255.255.255 UH 0 0 0
eth0
192.168.0.0 * 255.255.255.0 U 0 0 0
eth1
192.168.0.0 * 255.255.255.0 U 0 0 0
eth1
143.186.138.0 * 255.255.255.0 U 0 0 0
eth0
127.0.0.0 * 255.0.0.0 U 0 0 0
lo
default sg-cecil.sg.inp 0.0.0.0 UG 0 0 0
eth0
##############################################################################

Re: Help with 2 NIC

Edward Sedgemore — Wed, 28 Mar 2001 12:28:43 GMT

Youve got 2 NIC's pointing to 2 completely different subnets but you can only have 1 default gateway. So, this default gateway is where all traffic to BOTH subnets is being routed, so your default gatway server must be able to see both subnets. Is this so ? And why does your default gaetway show as 0.0.0.0 ??

Re: Help with 2 NIC

Low Han Ming — Thu, 29 Mar 2001 02:40:51 GMT

Sorry I have post into the wrong forum by mistake.
I am sorry for that and will repost in the correct group.

Re: Help with 2 NIC

Low Han Ming — Thu, 29 Mar 2001 02:56:01 GMT

Edward,

Thanks for your reply.

Firstly, I'm sorry about the posting in the wrong forum.

As for my setting, the default gateway is set to 143.186.138.1.
The reason is that this linux box is actually a server within a firewall.
Thus, for this machine to go to the internet, I'll need to set it's gateway to the gateway within the 143.186.138.* subnet. i.e. 143.186.138.1.
The 192.168.0.* subnet, can be said that it is a machine behind a firewall behind another firewall.

I'm not sure I've explain it correctly, but I'll glad to clarify any doubt if required.

And if it's fine to continue this thread in this forum, I'll be glad to. Otherwise, I'll repost in the linux -> networking forum.

Thanks again for the reply.

Regards.

Han Ming

Re: Help with 2 NIC

Phil Gregory_1 — Mon, 02 Apr 2001 11:41:53 GMT

Hi,
I'm not sure that running a server on top of a firewall is a good idea. As I see it, a firewall should be just that and only that.

however, if I understand correctly, you cannot see your internal networks from this server. You could try adding all your networks as static routes. If they are all 192.x.x.x subnets, a quick way to do this would be adding 192.0.0.0 255.0.0.0 to point to your internal router and let him sort the routing out for you. Alternatively run 'gated' to listen to your routers routing updates (on the internal interface only!) and your server will learn how to route internally for himself.
good luck.
Phil.

Re: Help with 2 NIC

Uffe Gavnholt_1 — Wed, 04 Apr 2001 15:30:30 GMT

The problem is not with the routing, all traffic on the same net as the interface will be forwarded through that interface, no matter of the defaut route setting.

What seems to be the problem to me, has something to do with the ifconfig - for the 2nd interface, no traffic, has been received, and all attempts to transmit traffic, has resulted in errors (jabbers probably).

To me this indicate bad cabling, misconfigured speed, and duplex settings.

How is your box wired?