Varnish and multiple interfaces

Henry M. Umansky humansky at Princeton.EDU
Tue Oct 4 13:59:14 CEST 2011

That is correct, both applications are binding to the same IP from the same machine, just different port addresses.

Henry Umansky
Web Development Services
Princeton University
humansky at

On Oct 4, 2011, at 4:11 AM, David Birdsong wrote:

> Henry sort of implied that the for the purposes of the test, nginx and
> varnish were configured similarly in the HTTP chain--that they
> theoretically sat in the same ip space and should, therefore, connect
> to the backend as from the same source ip.
> Right Henry?
> On Tue, Oct 4, 2011 at 1:01 AM, Mattias Geniar <mattias at> wrote:
>>> According to tcpdump, traffic from varnish is coming from eth0
>> (incorrect IP)
>>> and traffic coming from nginx is coming from eth0:0 (correct IP).
>> Apache logs
>>> are also confirming the IP information.
>> That's possible, if both eth0 and eth0:0 are in different subnets. If
>> your backend for nginx is in the same subnet as eth0:0 but in a
>> different subnet as eth0, it'll go via the eth0:0 alias.
>> So my guess would be that your varnish backend is in a different subnet
>> than your eth0:0 so it takes the default route via eth0?
>> Regards,
>> Mattias
>> _______________________________________________
>> varnish-misc mailing list
>> varnish-misc at

More information about the varnish-misc mailing list