Re: [fw-wiz] Layer 2 (stealth) firewalls - PBR?

If I were to speculate what the meaning of layer2 PBR is in this context,
this is what I would guess. I do this on my home router/firewall to
intercept port 80&443 and send it to a content filtering solution. It's
invisible to wireless network users.

# eth0=internet
# eth1= Wireless LAN (
# eth2=DMZ where content filter resides (
iptables -t mangle -A PREROUTING -i eth1 -p tcp --dport 80 -j MARK
--set-mark 0x1000
iptables -t mangle -A PREROUTING -i eth1 -p tcp --dport 443 -j MARK
--set-mark 0x1000
# filter
ip route flush table 100
ip route append via table 100
ip rule del pref 500
ip rule add pref 500 fwmark 1000 lookup 100

The filtering solution requires that the original source and destination IP
address remains intact, but the packets are forwarded to the MAC address of
the host

Maybe this is what he means?

-----Original Message-----
From: firewall-wizards-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:firewall-
wizards-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Darden, Patrick S.
Sent: Thursday, April 10, 2008 7:48 AM
To: Firewall Wizards Security Mailing List
Subject: Re: [fw-wiz] Layer 2 (stealth) firewalls - PBR?

Inaki, what vendor, which switch? Do you have a URL for us?
I still wonder: what is layer 2 PBR? What are its uses?
How does it function? Can you give us a good example, or
point us to a web site/document with a good example?

We've heard a lot of speculation, originated by some people
who were wondering themselves if such a thing was possible,
used by anyone, and what uses they were making of it.

So far, you are the only one to answer the original question!
(other than me speculating that it is not possible, nobody is using it,
and asking if anyone knows better.)

Glad you spoke up!

-----Original Message-----
From: firewall-wizards-bounces@xxxxxxxxxxxxxxxxxxxxx
[mailto:firewall-wizards-bounces@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of
Iñaki Arenaza
Sent: Saturday, April 05, 2008 3:38 PM
To: firewall-wizards@xxxxxxxxxxxxxxxxxxxxx
Subject: [fw-wiz] Layer 2 (stealth) firewalls - PBR?

"Darden," == Darden, Patrick S <darden@xxxxxxxx> writes:

Darden,> Layer 2, unlike IP, is on a flat fabric. There are no
Darden,> routers, no routing protocols, it is bridged. Every
Darden,> point on the fabric knows every other point on the
Darden,> fabric.

While not expert on the subject, I know of a switch vendor that is
adding PBR at layer 2 to their gear. They usually deal with some Layer
2 protocols (use in special industrial environments), and they want to
control where those Layer 2 packets go (output port) depending on
several factors like being unicast/multicast/broadcast, coming/going
to certain MAC addresses/addresses groups, etc.

So while not widely used, there are people doing 'crazy' stuff like

Saludos. Iñaki.

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