From:	SMTP%"RELAY-INFO-VAX@CRVAX.SRI.COM" 26-APR-1994 09:32:07.26
To:	EVERHART
CC:	
Subj:	RE: ACL entry for across-decnet account problem

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From: tillman@swdev.si.com (Brian Tillman)
Subject: RE: ACL entry for across-decnet account problem
Message-ID: <25APR94.09245199@swdev.si.com>
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Organization: Smiths Industries Aerospace & Defense
Date: Mon, 25 Apr 1994 09:24:51 GMT
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To: Info-VAX@CRVAX.SRI.COM
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In a previous article, vaxs09@v7.vitro.com wrote:
> 
>While this response may be strictly true, it is misleading.  SYS$REM_ID
>and SYS$REM_NODE are not a reliable indication of the remote user and
>node initiating the _current_ DECnet file access request.  The problem
>is that SYS$REM_NODE and SYS$REM_ID are set when the DECnet server process
>is first created.  If the same server process is re-used to satisfy a
>subsequent connect request from a different user or a different node,
>those logical names will remain unchanged.  I just checked and, under
>[OPEN]VMS/AXP 1.5, server processes can be re-used in exactly this way
>and the logical names are not refreshed with current information.  (In
>any case, the DECnet account's login procedure would not be re-invoked).
>To the best of my knowledge, this situation exists in all versions of
>VMS since the SYS$REM_NODE logical was introduced.
> 
>A more reliable way to get remote node information is to modify NETSERVER.COM
>or FAL.COM in SYS$SYSTEM and have it parse the remote node information
>out of the SYS$NET logical name.

And here's an example of that, in DCL:

$!
$!  Obtain the client's execution node name, the remote requesting node name,
$!  and the remote username
$!
$   node = f$getsyi( "nodename" )
$   gosub parsencb
..
$!
$ parsencb:
$!
$!  Parse the Network Control Block to obtain the remote node and user.  We do
$!  this because SYS$REM_NODE can be inaccurate when network servers are
$!  reusable.
$!
$   sys$net = f$trnlnm( "sys$net" )
$   flag = f$locate( "::", sys$net )
$   slash = f$locate( "/", sys$net )
$!
$   source_node = f$extract( 0, flag, sys$net )
$   source_user = f$edit( f$extract( flag+5, slash-flag-5, sys$net ), "trim" )
$   link_number = f$cvui( 0, 16, f$extract( slash+1, 2, sys$net ) )
$   return

-----------------------------+--------------------------------
 Brian Tillman               | Internet: tillman@swdev.si.com
 Smiths Industries, Inc.     |           tillman_brian@si.com
 4141 Eastern Ave., MS129    | Hey, I said this stuff myself.
 Grand Rapids, MI 49518-8727 | My company has no part in it.
-----------------------------+--------------------------------