Strange bridge behaviour, need sugestions

capzulu · 02-14-2014, 06:44 AM

I have this 3 machines with this setup:
Computer1----Computer with Ubuntu 12.04-----Computer2

Computer1 have IP 192.168.10.1 and Computer2 have 192.168.10.10.
My computer with Ubuntu have 2 ethernet interfaces. I want to create a bridge in Ubuntu so Computer1 and Computer2 can talk to each other.

I have created a bridge in Ubuntu with

Code:

sudo ifconfig eth0 0.0.0.0 down
sudo ifconfig eth1 0.0.0.0 down
sudo brctl addbr br0
sudo brctl addif br0 eth0
sudo brctl addif br0 eth1
sudo ifconfig br0 up
sudo ifconfig eth0 promisc up
sudo ifconfig eth1 promisc up

The command "brctl showstp br0" shows me that the state of eth0 and eth1 is forwarding.

Then I start tshark in bridge with

Code:

sudo tshark -i br0

If in Computer2 I try to ping Computer1 I get

Code:

ARP 60 Who has 192.168.10.1? Tell 192.168.10.10

In the bridge I get the ARP Request from Computer2 but I don't see ARP Reply from Computer1

When I run the tshark at Computer1 gets this

Code:

ARP 60 Who has 192.168.10.1? Tell 192.168.10.10
ARP 42 192.168.10.1 is at XX:XX:XX:XX:XX:XX (mac hidden)

With this I see that ARP gets passed through the brige, Computer1 receives the ARP and sends the reply but that reply don't go through the bridge.

Any ideas???

Thanks

pingwinowiewc · 02-14-2014, 09:45 AM

is smbc blocked at Ubuntu? this may be a cause.....
If you switch c1 with c3 by place what do you get?
Try pinging each other both on iddle (sxa) and working, maybe something blocks ethX?

capzulu · 02-14-2014, 11:56 AM

What smbc have to do with this?

You mean switching C1 and C2? It does the same thing.
It appears thar the bridge interfaces only "see" broadcast packets and not unicast.

Bladerox · 02-15-2014, 03:18 PM

I am not sure but bridges route traffic based on MAC and not on IP, so maybe they can´t handle hidden interfaces?