Firewall Wizards: RE: Borderware Ping Server

From: Ofir Arkin <ofir_at_sys-security.com>
Date: Tue, 23 Oct 2001 15:01:33 +0200

I was refereeing to the Unused near the DF and MF bits, and not the
unused which was with the TOS byte.

Ofir

-----Original Message-----
From: Matthew Kirkwood [mailto:matthew_at_sphinx.mythic-beasts.com] On
Behalf Of Matthew Kirkwood
Sent: ג 23 אוקטובר 2001 14:05
To: Ofir Arkin
Cc: firewall-wizards_at_nfr.com
Subject: RE: [fw-wiz] Borderware Ping Server

On Sat, 20 Oct 2001, Ofir Arkin wrote:

> We let the FW deal with only what we teach him to recognized, and what
> is a legitimate IPv4 traffic. This mean that if the firewall receives
> a packet with an Unused bit set, which is against the RFCs
> recommendations it drops it instantly because it is not a legit IPv4
> traffic. No questions asked.

Actually, in this case and perhaps others (unknown IP or TCP
options, for example) wouldn't the wisest approach be to zero
the unknown bit?

This is exactly what is causing so many problems with ECN at
the moment.

Matthew.

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Received on Oct 23 2001