Bridging interfaces and the internet

[Paul Howarth]

Nigel Wade wrote:
> Justin Willmert wrote:
> 
>> I just set up a desktop with two network cards and have got a bridge 
>> working between the two. That is not what my problem lies in though. I 
>> would like for the box to be able to connect to the internet also, but 
>> if I understand what I've set up correctly, I can't do that with my 
>> current setup. When I've tried to give one of the network cards an IP 
>> address, nothing but lo works, so I know there's something missing. 
>> I'll add my configuration at the bottom, but shortly, br0 is 
>> configured with an IP address, and eth0 and eth1 have none. Now, I 
>> know br0 is capable of at least a network connection because as I type 
>> this, I'm currently SSHed into into the box, but if I try to ping 
>> anything, all the packets are lost.

What IP address are you ssh'ed into the box from? Can you ssh back to 
that IP from the bridge machine? Might the ping issue be due to firewall 
rules (e.g. blocking ICMP packets)?

>> OK, so here are some of my thoughts and possible hints to a solution:
>>    1) My routing tables need another route, so I just figure out how 
>> to configure that and add a route.
>>    2) br0, eth0, and eth1 are incapable of an internet connection, in 
>> which case I need to create a virtual interface that can connect as if 
>> it were a separate interface that does the internet connecting.
> 
> 
> br0 is the network interface of the system. eth0 and eth1 are part of a 
> bridge and therefore completely transparent in the network.

Correct.

>> ===================== output of `route` =====================
>> Kernel IP routing table
>> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
>> 192.168.2.0     *               255.255.255.0   U     0      0      0    br0
>> 169.254.0.0     *               255.255.0.0     U     0      0      0    br0
>> 127.0.0.0       *               255.0.0.0       U     0      0      0    lo
>>             ===== 10 second or so delay here =====
>> default         192.168.2.2     0.0.0.0         UG    0      0      0    br0
> 
> 
> 
> You haven't set a netmask on the default route. It should be 
> 255.255.255.0 to match the network segment.

A netmask of 0.0.0.0 is normal for the default route.

Paul.