[BlueOnyx:26639] Re: Interfaces and default routes

[Darren Wolfe]

Hi,

> Indeed, the IPv6 autoconf=no should be set. I'll see to it.

Thank you!

> As for the default gateway? In my understanding there should be only one
> default gateway and that should apply to all interfaces. There may be
> additional routes that direct traffic destined for an internal network
> to the interface that the internal network is connected to. Or if
> OpenVPN is present, there ought to be a route that allows traffic to be
> directed to the private network that OpenVPN clients use.
> 
> But there shouldn't be two default gateways.


I shouldn't have confused the issue by mentioning two public default routes, but the idea that the default gateway should apply to all interfaces is an assumption that does not always hold. In my case, the public-facing interface has a public IP address as one would expect, but there is a DMZ network on a different interface and private address range which should not have the same default route applied to it.

I may be misinterpreting what I see on the boxes which is that when the server is rebooted.  This is how it looks:
eth0 is the public interface, eth1 is the private (ip's have been changed)

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         1.1.1.225       0.0.0.0         UG    100    0        0 eth0
0.0.0.0         1.1.1.225       0.0.0.0         UG    101    0        0 eth1
1.1.1.224       0.0.0.0         255.255.255.224 U     100    0        0 eth0
1.1.1.225       0.0.0.0         255.255.255.255 UH    101    0        0 eth1
192.168.17.0    0.0.0.0         255.255.255.0   U     101    0        0 eth1

I don't know what that 4th rule is attempting to do..

Sometimes eth1 will get the lower route metric, which results in no network connectivity. Even like the above, active monitor says:
The network interface eth0 is down. The network interface eth1 is down.

If the incorrect routes - the 2nd and 4th in the above, are removed, all is well.