On Thursday 26 June 2003 07.16, Aqil wrote:

> Now I want to limit my users to make just a certain
> number of connections, say 1 connection. So I put in
> my squid.conf these lines :

Connections you can limit, but not the number of windows. There is no 
real connection between the number of windows and the number of 
connections.

You have to allow for at least 4 connections per user plus some. Most 
browsers opens up to 4 connections while downloading a single page to 
speed up the download of images and other embedded objects. If you do 
not allow this then pages will often only download partially, and 
navigation may fail.

Some browsers maintain these 4 connections globally for all windows. 
Some opens up to 4 connections per active window currently 
downloadign a page.

When using this feature you also have to use "half_closed_clients 
off". And because there may be slight delays in the communication 
between the browser and proxy you need to allow for some slack in the 
number of connections i.e. if your policy is to allow 4 connections, 
then you need to allow about 6 connections to not falsely deny 
requests due to expected networking delays.

The maxconn acl is suitable for blocking "abuse" type use of the proxy 
such as download managers opening 100 parallell connections for the 
same object in order to steal as much bandwidth as possible and other 
similar things. It is also useful to block people running rouge proxy 
servers in your network giving access to unauthorized people.

Only to a very limited aspect can you limit the number of browser 
windows by the number of connections made via the maxconn acl. If you 
really want to limit the number of windows then this has to be done 
by software running on the client computer, enforcing a policy that 
there may only be a single browser window running on the computer.

Regards
Henrik

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