Networking help (connectivity between two lan cards on the same system)

babbutycoonq · 07-21-2011, 09:57 AM

Hello guys , please take a look at the attachment and can anyone please tell how to get internet connectivity to both system A and system B.
FYI: SYS1 has two lan cards. eth 0 connected to the router and eth1 connected to an eight port gigabit switch. Basically i need to isolate the traffic of the 48port switch to both system A and system B.

FYI ALL systems have the same hardware and software config as mentioned below

Operating sys : centos 5.6 x86_64
Processor : amd X6 phenom II
Storage : 2TB HDD
RAM : 16GB
motherboard : gigabyte us2h....something

please i need this to be setup in my office ASAFP.
Thanks

Nominal Animal · 07-21-2011, 12:54 PM

I don't have a suitable machine to verify, and I'm a bit rusty, so the following may not be exactly correct, but this should not be difficult at all.

On SYS1, make sure you have bridge-utils installed, then add a bridge between eth0 and eth1. If I remember correctly, you only need to add

Code:

BRIDGE=br0

to both /etc/sysconfig/network-scripts/ifcfg-eth0 and /etc/sysconfig/network-scripts/ifcfg-eth1, and create /etc/sysconfig/network-scripts/ifcfg-br0 containing

Code:

DEVICE=br0
TYPE=Bridge
ONBOOT=yes
BOOTPROTO=none
STP=yes

and run service network restart to reload all network settings. The network service will do all the magic with brctl et al. when the network is brought up.

But like I said, I'm unable to check this right now, so the above might not work without modifications. (Specifically, I cannot remember on which layer the bridge should work -- i.e. whether the IP addresses can be on the interfaces, or if they need to be assigned to the bridge instead. And it might need some extra routes using 'via' in the above files.)

babbutycoonq · 07-29-2011, 06:08 AM

Well i want the network connected to eth1 on a different subnet, and also need that network to be able to access the internet. I googled a lot... even tried setting up dns bind and dhcp. Dhcp works fine but no net connectivity. Since only eth0 is connected to my router what do i have to do get the internet working for the eth1 network, do i have to create a route or a bridge. Creating a bridge does not let me create a different subnet. Please help need to setup the servers ASAP.

TimothyEBaldwin · 08-16-2011, 01:14 PM

Enable IP forwarding on SYS1:
sysctl -w net.ipv4.ip_forward=1
and edit /etc/stsctl.conf to make it permanent.

Add route to 192.168.2.0/24 via 192.168.2.0 on ROUTER:
ip -4 route add 192.168.2.0/24 via 192.168.2.0