p2p: any suggestion?

[Luca Ferrari <fluca1978@infinito.it>]

Dear admins,
I've got a network of mine with a quite standard and simple configuration: a 
linux firewall with iptables and squid as web proxy. Now I'm fighting against 
p2p, and using the ipt_p2p and ipt_ipp2p modules I blocked p2p, until my 
users start using the proxy as a way to use p2p. My proxy has a simple rule 
mechanism, that deny access selecting source ips and mac address at the same 
time, but since a few users (like the boss) are unlocked, a few users start 
changing their ip/mac address in order to get unconditioned access. Now the 
question, as yuo can see, is: how can I block them? I found that using the 
browser rule in squid I can block p2p http headers, but other programs like 
microsoft money or antivirus update (avg) cannot work no more. Has anyone did 
tis before? Any suggestion to definetively block this? Could dhcp solve the 
problem, locking a mac to a specific ip and thus denying the ip/mac changes?

Thanks,
Luca
-- 
Luca Ferrari,
fluca1978@infinito.it