(Newbie:) Why use privoxy?

Keith Needels keithn at csh.rit.edu
Fri May 12 05:20:09 UTC 2006

Martin Möller wrote:

>Hi all,
>do I have to use privoxy when using Firefox as a browser? I've been
>reading somewhere that firefox can make DNS request via tor. Is this
The problem with not using Privoxy is that browsers will try to resolve 
the IP addresses of web sites you are visiting before requesting the 
page through Tor.  This means a request is being sent, unprotected, from 
your computer to whatever DNS server you use.  This request will have in 
plain text the address of the web site whose host name you are trying to 
resolve.  That defeats the purpose of Tor to a large extent.

When you use Privoxy, your browser won't try to resolve host names.  
Those host names will just be sent unresolved through Tor over TCP, and 
the exit node will resolve the hostname.  DNS requests aren't made 
directly through Tor because Tor only handles TCP traffic and DNS is 
UDP, but since the exit node is initiating the connection just as you 
would if you were unprotected with the destination, it can do the DNS 
lookup itself.

I hope this helps.


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