[ale] [Semi-OT] Intermittent web connection loss but not network loss

[Keith Morris - IQ]

I have been racking my brain on this and googling all over the place but 
have yet to find a solution and was hoping someone here my have some 
insight.

I have a network of about 40 machines that connect to the internet 
through a Smoothwall firewall running iptables. About a month ago, 
different clients on the network started losing web access. When this 
happens, most of the time they can still check email, ftp, IM, ping, 
access network shares, etc. just lose web access (though occasionally 
they will loose one of the other services). Interestingly, it doesn't 
happen to all clients at the same time, generally only 1 machine will 
exhibit this at a time.

The clients are WinXP machines.  Sometimes a simple ipconfig /release ; 
ipconfig /renew will bring the connectivity back, but a logoff/logon 
will ALWAYS bring the web connection back.

DHCP and DNS is provided by a win2K ActiveDirectory server. It seems 
that the Smoothwall should be completely unaware of the domain structure 
and simply be routing based on MAC address and IP so it doesn't seem 
that the Smoothie would just intermittently start dropping port 80 
requests from a single client then recover after the user logged off and 
back on (as the ip doesn't get touched in that situation).

I'm beating my head against a wall trying to figure it out. Any ideas?
-- 
:: Keith Morris
:: Creative Director
:: Design / Effects
:: IQ television group
:: Atlanta, GA
:: 404.255.3550
:: http://www.iqtv.com