Great Circle Associates Firewalls
(December 1994)
 

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Subject: Re: port 113 - auth
From: Jonathan Heiliger <loco @ boom . com>
Date: Thu, 8 Dec 1994 15:10:25 -0800 (PST)
To: Matthew Harding <matt @ worldlinx . com>
Cc: firewalls @ greatcircle . com
In-reply-to: <9412052130 . AA21185 @ jupiter . worldlinx . com>

On Mon, 5 Dec 1994, Matthew Harding wrote:

> We have been receiving numerous queries on this port... can anyone tell
> me if it is used by some standard program, or if we should be concerned
> at all regarding this activity? Please respond directly and I will post
> a summary in a few days.

authd, pauthd, identd and ident all descend from RFC 931; which as other 
have said are used to determine who is opening a TCP connection to your 
machine.  RFC 1413 defines how this "information" is returned.

Generally speaking I would venture to say that is on the safer side of 
services that can be allowed.  If you choose to disallow it however, I 
would imagine there would be problems if you also sent a ICMP Unreach -- 
causing all TCP connections to close between the two hosts. (Yours and 
the one that you're querying)

If you do choose to allow it, I would spend some time considering how 
trustworthy the auth data you're getting back is.  What if someone 
purposely hacked their side to falsify information?  Then your logging 
based on identity would be worthless.


--
Jonathan Heiliger	   |      "Because Windows/NT is too important
The Boom Group, Inc.	   |       to entrust to Intel" - MIPS
loco @
 boom .
 com		   |		             Open RISC Technology



References:
Indexed By Date Previous: Re: Information please
From: "Daniel O'Callaghan" <danny @ www . unimelb . edu . au>
Next: Information about firwall-1
From: xmerino @ ecnet . ec (Xavier Merino)
Indexed By Thread Previous: Re: port 113 - auth
From: Jason Matthews <jason @ dickory . SDSU . Edu>
Next: Re[2]: port 113 - auth
From: hharamis @ cohesive . com

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