[squid-users] Capture incoming information from one squid

[Amos Jeffries]

On 20/08/22 11:20, Marcelo wrote:
> Thanks Alex,
> 
> 1- Is it possible to provide me with an example of squid.conf of both parent
> and child squids?
> 
> I am having very basic doubts about cache_peer and its very hard to find
> complete squid.confs over the internet.
> 

FWIW, *complete* squid.conf are usually useless because every network is 
different. What you actually want is the *pieces* that do what you need.


> 2- cache-peer really routes the connection to the second squid server or
> just look for a hit in a second server's cache?
> I need the second server to not just authenticate the user, but to know from
> which port the user got in the first squid server in order to forward this
> user through different routes based on this incoming port number.


cache_peer directive is just the settings for *how* to connect to a 
particular server. What URL format to use, whether to use TLS/SSL or 
not, any non-80/443 port to connect to, what/how to pass login 
credentials, etc.

cache_peer_access determines what traffic can (or must) be sent on a TCP 
connection setup with a cache_peer's settings.


To pass unusual data like the original client info you should add a 
Forwarded header with the relevant details.


So, in your frontend proxy you have:

   # Special parent proxy for some traffic
   cache_peer ... name=X

   # which traffic to send to the special parent
   acl specials dstdomain ...

   never_direct allow specials
   cache_peer_access X allow specials
   cache_peer_access X deny all

   # markup the traffic with Forwarded details
   forwarded_for transparent
   request_header_add Forwarded "for=%>a;by=_%lp" specials


In your backend Squid this ACL below matches the Forwarded header 
received there. Use it as necessary to decide your traffic handling:

   # match when frontend marked port X as receiving
   acl portX req_header Forwarded ;by=_X(,|$)



HTH
Amos