nanog mailing list archives
Re: request for help w/ ATT and terminology
From: "William Herrin" <herrin-nanog () dirtside com>
Date: Fri, 18 Jan 2008 23:12:16 -0500
On Jan 18, 2008 10:18 PM, Roland Dobbins <rdobbins () cisco com> wrote:
host.somewhere.net in a firewall rule in a PIX/ASA/etc. as opposedIt's not only a security issue, but a performance issue (both resolver and server) and one of practicality, as well (multiple A records for a single FQDN, CNAMEs, A records without matching PTRs, et. al.). The performance problem would likely be even more apparent under DNSSEC, and the practicality issue would remain unchanged.
Roland, For renumbering purposes, you could reasonably expect the firewall to perform the translations once when rebooted or reset, after which it would use the discovered IP addresses. This would only fail where the firewall was being operated by someone in a different administrative domain that the engineer who has to renumber... And those scenarios are already indicative of a security problem. Unfortunately, we're all ignoring the big white elephant in the room: spam filters. When a large flow of email suddenly starts emitting from an address that didn't previously send significant amounts of mail, a number of filters squash it for a while based solely on the changed message rate. This can be very traumatic for the engineer trying to renumber and it is 100% outside of his realm of control. And of course, you lose all of the private whitelists that you talked your way on to over the years where you no longer have a valid point of contact. Renumbering is a bad bad thing. Regards, Bill Herrin -- William D. Herrin herrin () dirtside com bill () herrin us 3005 Crane Dr. Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004
Current thread:
- Re: request for help w/ ATT and terminology, (continued)
- Re: request for help w/ ATT and terminology Joe Greco (Jan 17)
- Re: request for help w/ ATT and terminology Valdis . Kletnieks (Jan 17)
- Re: request for help w/ ATT and terminology Steven M. Bellovin (Jan 17)
- Re: request for help w/ ATT and terminology Crist Clark (Jan 17)
- Re: request for help w/ ATT and terminology Valdis . Kletnieks (Jan 17)
- Re: request for help w/ ATT and terminology Steven M. Bellovin (Jan 17)
- Re: request for help w/ ATT and terminology Joe Greco (Jan 18)
- Re: request for help w/ ATT and terminology Joe Greco (Jan 17)
- Re: request for help w/ ATT and terminology Joe Greco (Jan 17)
- Re: request for help w/ ATT and terminology Brandon Galbraith (Jan 17)
- Re: request for help w/ ATT and terminology Roland Dobbins (Jan 18)
- Re: request for help w/ ATT and terminology William Herrin (Jan 18)
- Re: request for help w/ ATT and terminology Roland Dobbins (Jan 18)
- Re: request for help w/ ATT and terminology Patrick W. Gilmore (Jan 16)
- Re: request for help w/ ATT and terminology Seth Mattinen (Jan 16)
- RE: request for help w/ ATT and terminology Jason Biel (Jan 16)