[squid-users] Transparent Proxy Configuration

[Chris Greene]

I’ve had Squid running on Ubuntu for a few weeks.  I’d configured the proxy 
settings in the browsers.  Everything has been working well and I've been 
pleased with the results.  But now I need to make this a transparent proxy 
and I’m running into trouble & need some help.

I’ve got a Destination NAT rule set up on my router to forward TCP port 80 
traffic to my proxy.  And I removed proxy configuration settings from the 
browsers.  After enabling this DNAT rule, I see requests being logged to 
/var/log/squid3/access.log.

Results when navigating to http://www.google.com:
The following error was encountered while trying to retrieve the URL: /
   Invalid URL
Some aspect of the requested URL is incorrect.
Some possible problems are:
-Missing or incorrect access protocol (should be “http://” or similar)
-Missing hostname
-Illegal double-escape in the URL-Path
-Illegal character in hostname; underscores are not allowed.


Next, I added "intercept" to http_port like so:
   "http_port  192.166.2.55:3128  intercept"
Results: Access Denied.

My abbreviated /etc/squid3/squid.conf looks like this:
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
http_access allow localhost manager
http_access deny manager
http_access allow localhost
http_access allow all

I'm new to Squid/Ubuntu, so I likely overlooked something.  What am I 
missing?  What troubleshooting step(s) should I take next?
-DG