[Gllug] how to check for a transparent proxy

[Formi]

On Sun, 1 Dec 2002, Xander D Harkness wrote:

> Mark Lowes wrote:
> > On Sun, 2002-12-01 at 03:42, Xander D Harkness wrote:
> >
> >>I am told by my connectivity provider that port 80 traffic
> is not
> >>filtered or cached.  I pay for a clean business connection
> and I would
> >>expect it not to be cached / cached.
> >>
> >>If I browse to amazon.com or amazon.co.uk all of the links
> to the images
> >>are broken.  For a long time I thought it was amazon.
> >
> >
> > telnet <IP you know isn't running anything on port 80> 80
> >
> > if you get connection refused then there's no proxy, if you
> get a
> > session then you're hitting a proxy.
> >
> So, it looks like it is a local problem.
>
> ######################################
>
> I grabbed some of the access log from squid:
>
> TCP_MISS/503 1609 GET
> http://images-eu.amazon.com/images/P/1855496771.02.TZZZZZZZ.jpg
> - NONE/-
> text/html
>
> ##################################
>
> If I put this URL in a browser I get:
>
> #####################################
>
> The following error was encountered:
>
>      Unable to determine IP address from host name for
> images-eu.amazon.com
>
> The dnsserver returned:
>
>      Name Error: The domain name does not exist.
>
> ####################################
>
> So I ran a few dns checks
>
> #####################################
>
> dig amazon.com
>
> no IP given
>
> dig www.amazon.com
>
> 207.171.183.16
>
> dig images-eu.amazon.com
>
> CNAME   images-eu.amazon.speedera.net.
>
> ######################################
>
> Now this starts to look interesting.  Over the last year I
> have had a
> lot of pop-ups, pop-unders, spam and many other annoyances
> from speedera
> so in my nameservers I put an a record for speedera pointing
> to a good
> IP which would server a blank page of html.  (pointing to
> 127.0.0.1
> causes most browsers to give a pop-up error message)
>
> Aside from the errors in Amazon all has been well and all who
> use the
> proxies and dns servers have been happy.
>
> I guess a better answer is to put speedera in the proxy ban
> file and the
> mail rbl list :-)
>
> Thanks for all the suggestions.
>
> I am happy that I know know a number of methods to check for a
> transparent proxy and have solved my hiccough.
>
> Kind regards
> Xander
>

 I found a little redirector that checks a table of ad-servers
 and redirects squid to a web server on the local machine just
 serving a transparent 1 pixel gif.

 I'm using khttp, wich is really small and quick, and requires
 very little effort to set up.

 The program is called asqredir.


-- 

    V
   . .                              Formi
    v
   / \ GZ           MDK 9.0 ThinkPad 560E
  // \\/
 /( _ )     Linux Registered User #235743
  ^   ^


-- 
Gllug mailing list  -  Gllug at linux.co.uk
http://list.ftech.net/mailman/listinfo/gllug