dual wan questions

shinystuffrox · 02-06-2008, 12:52 PM

I have 2 nics
eth0 is 192.168.1.100 connected to modem0
eth1 is 192.168.254.2 connected to modem1

Azureus, the java bittorent client, has a feature that allows a user to bind azureus traffic to a specific ethernet device.

in azureus I have it set to bind to eth1(i use tcp 6666 and udp 6667 in azureus)...

netstat -an | grep 666:

Code:

netstat -an | grep 6667
tcp        0      0 192.168.1.100:45678     208.100.23.31:6667      ESTABLISHED 
tcp        0     32 192.168.1.100:33468     70.85.129.210:6667      ESTABLISHED 
tcp        0      0 192.168.1.100:48351     85.17.111.117:6667      ESTABLISHED 
tcp        0      0 192.168.1.100:49091     212.178.133.174:6667    ESTABLISHED 
udp        0      0 192.168.254.2:6667      0.0.0.0:*

notice the bottom one where 0.0.0.0 is, that it is indeed bound to eth1, so why is there bittorrent traffic on eth0/1.100?

route produces:

Code:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
192.168.254.0   *               255.255.255.0   U     0      0        0 eth1
loopback        *               255.0.0.0       U     0      0        0 lo
default         192.168.1.1     0.0.0.0         UG    0      0        0 eth0
default         192.168.254.254 0.0.0.0         UG    1      0        0 eth1

--thanks in advance

centauricw · 02-07-2008, 08:23 AM

You can really only have one default gateway. A default gateway is used whenever there is no specific route to a remote address in the routing table. In your case, you have chosen to add two default routes (never recommended). The default route for eth0 is listed in the routing table first, so this will be be default route that is actually used. The default route for eth1 will never be used since it is listed in the routing table second. Once the networking stack finds a route through the default route on eth0, it stops looking in the routing table and the default route on eth1 is never found.

shinystuffrox · 02-07-2008, 08:35 PM

are you sure it's going through eth0 because it's the first default on the list or because the matric is 0, which means it's a higher priority than eth1 which has a metric of 1. what if I made the metric of both cards the same?

centauricw · 02-09-2008, 12:02 AM

Your right about the metric. I didn't notice that. I don't have a dual Internet connection, so I can't say exactly what would happen, but I think if they're the same metric, what I said before about the first one in the routing table should apply.