[Netalyzr] intranet proxy detection gets web server instead of proxy

Alex Woick alex at wombaz.de
Tue Dec 11 05:26:52 PST 2012

I have a machine with a squid proxy (port 3123) and a web server (port 
80) running in my intranet. The proxy configuration for my machine is 
distributed with a proxy.pac file. This way, my browser contacts the 
intranet proxy, which contacts remote web servers directly.

With this configuration, netalyzr detects a wrong proxy in my intranet. 
It probes the correct machine but misinterprets the apache web server on 
port 80 als proxy, which is not configured as proxy. I removed the 
mod_proxy.so and corresponding modules from httpd.conf, so it really 
cannot. This results in wrong reports from netalyzr that a proxy alters 
responses and performs broken caching.

This is an excerpt from the client logfile:

009,582  test-7| Starting checkURL
009,687  test-7| Response code 200
009,689  test-7| Global client addr via HTTP is
009,689  test-7| Suspecting proxy at linux1.wombaz.localnet:80, verifying.
009,691  test-7| connected to 'linux1.wombaz.localnet/' in 1 ms
009,697  test-7| read response headers in 6 ms
009,697  test-7| HTTP headers received: Date Server Content-Length Connection Content-Type
009,697  test-7| Connection header is close
009,697  test-7| Content length is: 339
009,697  test-7| Got all content
009,697  test-7| Proxy confirmed via ID string in payload.

According to proxy.pac, the proxy runs on linux1.wombaz.localnet:3128, 
and according to the X-Cache-Lookup header applications could be able to 
determine the correct port 3128 even without proxy.pac.
If I manually configure the browser (Firefox) to directly connect to 
websites, no proxy is detected - which is fine.

This is the link for the session with proxy autoconfiguration file:

using the cli version, netalyzr doesn't detect any proxy (which is fine):


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