Firewall Wizards mailing list archives
Re: How does your firewall handle DNS messages > 512 oct ets?
From: "Horvath, Kevin M." <KEVIN.M.HORVATH () saic com>
Date: Wed, 30 Aug 2006 12:30:16 -0400
Dave, As for the Pix it is configurable to allow dns max packet length to be greater than the default of 512 bytes. Anything over the configured length will be silently drop. It can also be disabled in which it will treat it as any other UDP packet and not worry about length. I am not familiar enough on the other firewalls to say but remember google is your friend. Hope this helps in your quest. Kevin M. Horvath CISSP, CCSP, GCIH, INFOSEC, CQS-FW, CQS-VPN, CQS-IDS, CCNA SAIC Integrated Security and Systems -----Original Message----- From: firewall-wizards-bounces () listserv cybertrust com [mailto:firewall-wizards-bounces () listserv cybertrust com] On Behalf Of Dave Piscitello Sent: Tuesday, August 29, 2006 3:14 PM To: Firewall Wizards Security Mailing List Subject: [fw-wiz] How does your firewall handle DNS messages > 512 octets? Hi all, I am trying to understand how different firewalls behave when they receive a UDP datagram containing a DNS message that uses EDNS0 (RFC 2671) to support message sizes greater than the 512 maximum specified in RFC 1035 (original DNS). Specifically, - does your firewall block/silently discard such messages by default? - do you know the command to allow the message if blocked by default? I've found dozens of claims that firewalls don't handle EDNS0 correctly, but after a long search, I've only found URLs indicating that Firewall-1 and Pix block by default and have workarounds. I'm curious whether SonicWall, Netscreen, Symantec, etc. behave similarly. I'd also be curious to learn the behavior of IPS devices and DNS proxies (Watchguard, WinProxy, etc). You can send replies directly to me and I'll compile responses and post to the list to save electrons. Thanks in advance, Dave _______________________________________________ firewall-wizards mailing list firewall-wizards () listserv icsalabs com https://listserv.icsalabs.com/mailman/listinfo/firewall-wizards
Current thread:
- Re: How does your firewall handle DNS messages > 512 oct ets? Horvath, Kevin M. (Aug 30)