Firewalls: Re: Stateful Packet Filters vs. Proxies

Firewalls
(June 1997)

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Subject:	Re: Stateful Packet Filters vs. Proxies
From:	Geoff Mulligan <geoff @ mulligan . com>
Date:	Mon, 09 Jun 1997 12:32:37 -0600
To:	"Kelly E. Gibbs" <kgibbs @ best . com>
Cc:	Ryan Russell/SYBASE <Ryan . Russell @ sybase . com>, Bill Stout <stoutb @ pios . com>, firewalls <firewalls @ GreatCircle . COM>
In-reply-to:	Your message of "Fri, 06 Jun 1997 18:51:55 PDT." <Pine . SGI . 3 . 95 . 970606184832 . 16893A-100000 @ shellx . best . com>

kgibbs @
 best .
 com said:
> At what level does the NAT occur in the OSI model?  So far I've heard
> 2 and 4... whats the right answer? 

NAT happens at the ip address level and requires modification to the IP and 
TCP/UDP headers.

It may also require changes to the application data as in FTP when the IP 
address (or port) is embeded in the application data.

	geoff

References:

Re: Stateful Packet Filters vs. Proxies
From: "Kelly E. Gibbs" <kgibbs @ best . com>

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