Application layer firewall on FreeBSD, is it possible ?

Daniel Dvořák dandee at
Wed Aug 31 00:14:59 GMT 2005

Okay, thank you for advise. Maybe I did not understand fully but ...

... but you know, proxy is not what I am asking, proxy is not firewall.

We do not need to restrict everything and all members.

We like full routeable network with full access to IPv6 / IPv4 internet
without any necessary action like configure proxy clients at all pc´s our

We only want to deny only p2p applications by default for all pc´s
regardless of used protocol/ports and to allow grantting access to p2p
networks each members in individual way, because we have to prevent another
letter from our ISP which was contacted by BSA that from our public IP (
from one member in private ip space ) ... traffic ... share ... violate ...
authorial law. 

So of course it must be combination of IP and application osi model

Gateway server should check all packets and their contents to decide if
allowed or denied in fast way like l7-filter on Linux OS.

So is it possible on FreeBSD OS ?


Since my question here is not right like somebody told me, this is last
e-mail in this mailling list for this theme, and I send it to
freebsd-question, freebsd-ipfw and freebsd-pf mailling lists.


-----Original Message-----
From: owner-freebsd-current at
[mailto:owner-freebsd-current at] On Behalf Of Charles Swiger
Sent: Tuesday, August 30, 2005 9:51 PM
To: dandee at
Cc: freebsd-current at
Subject: Re: Application layer firewall on FreeBSD, is it possible ?

On Aug 30, 2005, at 2:58 PM, Daniel Dvořák wrote:
> let me ask you for task "how to control p2p applications and their 
> traffic with dynamic ports from user´s commputers on gateway".
> We are small wireless community and have shared access to internet for 
> all members. Core members decided to control p2p traffic by default 
> and to allow each person in individual way, after showing their 
> knowledge of authorial low. :)
> But since many dc hubs, edonkey servers, bittorents web trackers and 
> so on use dynamic not standard ports, how to control it ?

Start with a "deny all" policy, and use L7 proxies like squid for the
specific protocols like HTTP which you want to permit.  If you're really
serious about controlling the traffic, don't let your router talk to
anything but your proxy server in order to be certain that the client
machines have to go through that.


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