Layer 7 firewall

[Ali Jawad]

Hi
I need to use some QOS filtering to filter p2p, msn and other applications..so I want to use a layer 7 firewall..Ive seen some patches 
for iptables but I wana get some feedback from you guys who tried layer 7 apps or patches..who has tried a layer 7 filtering setup and it worked 
just fine for him..with links to tutorials if possible.. thx for any suggestions

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With Regards Ali Jawad