nanog mailing list archives
Re: SlashDot: "Comcast Gunning for NAT Users"
From: Keith Woodworth <kwoody () citytel net>
Date: Thu, 31 Jan 2002 14:02:38 -0800 (PST)
On Thu, 31 Jan 2002, David Charlap wrote: |+ |+Keith Woodworth wrote: |+> |+> From a technical standpoint how does one detect NAT users over the |+> network? |+ |+You can't deterministically do so, but there are some telltale signs. |+NAT implementations (at least the ones I've seen) tend to choose very |+large port numbers (above 30,000) for the ports that they generate. That was my understanding. |+Anybody who tries to detect NAT through these kinds of heuristic methods |+will end up with a lot of false positives and false negatives. And if |+it becomes a problem, the NAT implementors will simply alter their code |+to make it impossible to distinguish from a single host's traffic. Thats sort of what I thought. Ive looked at some tcpdumps that are coming from a FreeBSD machine doing NAT a while ago to see what was in the packets exactly and I could not see how you could tell that box was doing NAT really. But I'm not completely proficient in deciphering packets so I may have missed something along the way. Keith
Current thread:
- Re: your mail, (continued)
- Re: your mail Andy Walden (Jan 31)
- Re: Fwd: SlashDot: "Comcast Gunning for NAT Users" William Allen Simpson (Jan 31)
- Re: Fwd: SlashDot: "Comcast Gunning for NAT Users" Valdis . Kletnieks (Jan 31)
- RE: SlashDot: "Comcast Gunning for NAT Users" Daniel Golding (Jan 31)
- RE: SlashDot: "Comcast Gunning for NAT Users" Daniel Senie (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Jon Mansey (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Marc Pierrat (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Dan Hollis (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Keith Woodworth (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" David Charlap (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Keith Woodworth (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Jared Mauch (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Daniel Senie (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" kevin graham (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Marc Pierrat (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" Paul Bradford (Jan 31)
- Re: SlashDot: "Comcast Gunning for NAT Users" EA Louie (Jan 31)
- Message not available
- Re: SlashDot: "Comcast Gunning for NAT Users" Matt Barrette (Jan 31)
- Re: Fwd: SlashDot: "Comcast Gunning for NAT Users" jerry scharf (Jan 31)
- Re: Fwd: SlashDot: "Comcast Gunning for NAT Users" Simon Higgs (Jan 31)
- Re: Fwd: SlashDot: "Comcast Gunning for NAT Users" Eric A. Hall (Jan 31)