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Old 08-09-2004, 03:28 PM   #1
jdiemer
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Registered: Aug 2004
Distribution: Redhat Enterprise
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2 NICs w/o bridging RedHat Enterprise


I'm installing a 2nd network card in a RedHat Enterprise-Professional Workstation machine. Each card will be plugged into a separate network.

I want the 2 networks to be completely isolated from each other. Does Linux automatically do any bridging/routing? How can I be guaranteed that these 2 networks will be isolated and invisible from each other?

Thanks,
Jacob
 
Old 08-09-2004, 04:41 PM   #2
ToniT
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iptables --policy FORWARD DROP
and check that forwarding is disabled, eg. /proc/net/ipv4/ip_forward is zero.
Doing only one of these should do it, but it is not bad to do it twice.
 
Old 08-10-2004, 04:03 PM   #3
jdiemer
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Thanks for that help...now my problem is.....

When I plug in the 2nd network card, my internet stops working. I've tried pinging some sites, and it looks like it's pinging them from the internal LAN card. How can I force it to use the other card?
 
Old 08-10-2004, 07:30 PM   #4
ToniT
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Does they stop working when you just plug the card in to the system, or when you connect the second one to the network?

If first, then one probable explanation is that the new card is probably known as eth0 and old one has moved from eth0 to eth1 and your network settings refer to the wrong card.
To fix it, either fix your settings or the naming of the card. Naming can be fixed either by using ifrename or loading the network drivers in different order.

If second, are you using dhcp to set those interfaces up? It might be, that information got from second network sets too many settings and especially messes up the default gateway.
What are outputs of route -n, ifconfig -a and the contents /etc/resolv.conf before and after the connection?
 
Old 08-11-2004, 03:26 PM   #5
jdiemer
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I got it working.

When the computer booted up, kudzu detected the network card and asked for my settings. I filled in a static ip, and left its settings for mask, gateway, and nameserver.

This time I removed the gateway and namesever settings, and everything appears to be working correctly.

Thanks for your help!
 
  


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