[GRLUG] Multiple Squid Instances

[Olding, Jim]

I have a CentOS box running 2 instances of Squid, each one bound to a
separate interface:

Eth0 - 10.254.2.54 - 'Filtered' squid instance
Eth0:0 - 10.254.2.56 - 'Unfiltered' squid instance

The filtering is actually done by a web appliance which looks at the
source IP of HTTP requests and determines if they should be forwarded,
filtered for content, or blocked.

The issue I'm running into is that if a user is on the Unfiltered
instance, Squid is using the IP of the main interface (eth0) and not the
virtual interface it is bound to (eth0:0) for outbound requests.
Therefore, the web filter appliance sees the request coming from
10.254.2.54, which matches its 'web filter' rule, and it blocks some
things that shouldn't be blocked.

Does anyone know any way to get squid to maintain the IP address of the
interface it is listening on in its outbound HTTP requests?