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Old 03-18-2007, 10:57 PM   #1
ronban
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Ethernet Bridging on a firewall


Hi everybody,
We installed CentOS on all our servers. We are having some problems in configuring the landscape and stabilizing the environment.

This is what we are looking at:

ADSL ROUTER (192.168.99.1)
|
| (eth0) 192.168.98.4
GATEWAY SERVER (CENTOS )
| (eth1) 192.168.99.4
|
|
|
|
SWITCH (DLINK)
|
|
|
|
| (192.168.99.0/24)
OTHER SERVERS AND COMPUTERS


Now, the gateway server has 2 interfaces. eth1 being the internal interface and eth0 being the external interface. The internal interface serves the internal network with a DHCP Server.

This above conf is working fine. We applied some standard IP table rules on the gateway.

The problem comes when we try using a bridge for eth1. We will need to install openVPN on the server and need to operate it in the bridge mode. But as soon as the bridge is started and eth1 is binded to it, no one can access the system from outside. No-one can also access internet from inside the network. do we need to use ebtables or spanning tree protocol? Building of this landscape has been a bottleneck for our project.

The openvpn clients need to get their ips from the dhcp server runnign on eth1.

I have attached a file described the landscape in detail in jpg file here.

http://www.indience.com/landscape/landscape.jpg

Any help is appreciated.

Regds
Roney

Last edited by Capt_Caveman; 03-19-2007 at 08:04 PM.
 
Old 03-19-2007, 05:16 PM   #2
Brian1
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The ip for the adsl router to the eth0 are using different Class C IP ranges. Is that correct?
Other than that ebtables and Openvpn is above me.

Brian
 
Old 03-19-2007, 09:21 PM   #3
ronban
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yes, but arent these IP's be used in the local IP range. If you have the saem config, can you paste your config files please. That will be very helpful
 
Old 03-19-2007, 10:39 PM   #4
merize147
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Quote:
Originally Posted by ronban
The problem comes when we try using a bridge for eth1. We will need to install openVPN on the server and need to operate it in the bridge mode.
Bridging is a layer 2 function and VPN works with IP's which is layer 3. Hence you can't have both.

-
 
Old 03-20-2007, 12:08 AM   #5
ronban
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what about a brouter ? cant we install a brouter on a linux box??
 
Old 03-20-2007, 01:58 AM   #6
jschiwal
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Wouldn't it be better to have your remote sites on different subnets? Eth0 will need to be on the same subnet as the modem to operate. The LAN addressing for the remote sites is encapsulated in the VPN. There are numerouse VPN howtos. I entered "Linux VPN" in google and got pages of responses.

What the remote sites use, such as cisco or another linux box may determine what solution you need to work on.

Last edited by jschiwal; 03-20-2007 at 02:04 AM.
 
Old 03-20-2007, 08:29 AM   #7
merize147
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Why the big push for a bridge?
 
  


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