Firewall Wizards mailing list archives
Re: Does blocking TCP DNS packets keep your Bind safe?
From: Andrew Huffer <ahuffer () tellabs com>
Date: Fri, 9 Mar 2001 09:36:37 -0600 (CST)
Don: I agree that TCP transfers should only be allowed from the authorized secondaries. This should be enforced first by the BIND configuration and then backed up by the firewall configuration. This is really important. Doing this limits the possiblity of a hack easily getting a map of the network, thereby making him/her work a little bit harder to create a profile for the attack. General queries are UDP. It is still possible to overflow named via UDP, depending on the version of BIND we are talking about of course. /ahuffer/ On Wed, 7 Mar 2001, Don Kendrick wrote:
******* Repost, sorry wrong email address used ********** OK, here I go again breaking things :) Over the years I've argued about blocking icmp at the border routers. Steve Bellovin et al would usually argue that it breaks path MTU, etc. I'd usually argue that we can rely on path MTU being negotiated elsewhere in the path (LAN vs. WAN bandwidth)...but I digress Here's what I am suggesting: 1. We should all only do zone transfers (TCP) with known secondaries. 2. Most if not all "normal" queries needed by legit Internet traffic are UDP. Why not just block port 53 TCP connections at the border routers except for our secondaries. Is it possible to do a buffer overflow or other DNS/Bind exploit via UDP? I don't know the answer, I'm asking. Don Don Kendrick, CNE, CCNA, GCIA, CISSP _______________________________________________ firewall-wizards mailing list firewall-wizards () nfr com http://www.nfr.com/mailman/listinfo/firewall-wizards
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Current thread:
- Does blocking TCP DNS packets keep your Bind safe? Don Kendrick (Mar 09)
- Re: Does blocking TCP DNS packets keep your Bind safe? Gary Flynn (Mar 10)
- Re: Does blocking TCP DNS packets keep your Bind safe? M. Dodge Mumford (Mar 10)
- Re: Does blocking TCP DNS packets keep your Bind safe? David Lang (Mar 10)
- <Possible follow-ups>
- Does blocking TCP DNS packets keep your Bind safe? Don Kendrick (Mar 09)
- Re: Does blocking TCP DNS packets keep your Bind safe? John Adams (Mar 10)
- Re: Does blocking TCP DNS packets keep your Bind safe? Crist Clark (Mar 10)
- Re: Does blocking TCP DNS packets keep your Bind safe? Jeff Sedayao (Mar 10)
- Re: Does blocking TCP DNS packets keep your Bind safe? Andrew Huffer (Mar 10)
- Re: Does blocking TCP DNS packets keep your Bind safe? Bill_Royds (Mar 10)
- RE: Does blocking TCP DNS packets keep your Bind safe? Ben Nagy (Mar 11)
- Re: Does blocking TCP DNS packets keep your Bind safe? Luca Berra (Mar 13)
- RE: Does blocking TCP DNS packets keep your Bind safe? Todd (Mar 13)
- Re: Does blocking TCP DNS packets keep your Bind safe? Darren Reed (Mar 14)
- Re: Does blocking TCP DNS packets keep your Bind safe? Todd (Mar 14)
- Re: Does blocking TCP DNS packets keep your Bind safe? Darren Reed (Mar 14)