Path: utzoo!attcan!uunet!pyrdc!pyrnj!rutgers!apple!claris!skip
From: skip@claris.UUCP (Brian D. Schipper)
Newsgroups: comp.protocols.appletalk
Subject: Re: Inter*Poll; Socket 4 from outer space?
Message-ID: <5341@claris.UUCP>
Date: 13 Sep 88 21:29:30 GMT
References: <3479@phri.UUCP>
Reply-To: skip@claris.UUCP (Brian D. Schipper)
Organization: Claris Corporation, Mountain View CA
Lines: 19

In article <3479@phri.UUCP> roy@phri.UUCP (Roy Smith) writes:
>	I just got my copy of Inter*Poll.  Playing around I noticed that if
>I ask for unnamed objects, I get something without a name on socket 4 of
>virtually everything on the net.  Here's the output (slightly reformatted

[... output deleted...]

>The last two entries are a kbox running KIP.  The question is, what are
>these mystery socket 4 things?

Socket 4 is used to support the Echo Protocol.  It simply listens for
packets and echoes them back to their sender.  This can be used to
determine if a particular node is alive, and also to find out how
long it takes to reach that node.  Echo Protocol is mentioned briefly
in Inside Mac V-522 and described in more detail in Inside AppleTalk.

-- 
UUCP: {ames,apple,portal,sun,voder}!claris!skip   Applelink: SCHIPPER1
Internet: claris!skip@ames.arc.nasa.gov           Phone: 415-960-2618