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Re: Problem with ascend pipeline routers.
From: jshaw () INSYNC NET (Joe Shaw)
Date: Thu, 28 May 1998 15:53:53 -0500


On Wed, 27 May 1998, Eric Thacker wrote:

Date: Tue, 26 May 1998 14:19:30 -0700
From: support <support () ascend com>
To: eric () caffrey net
Subject: RE: Ticket #238563

Eric:

The pipeline has no way of telling what is a legit telnet and what is
not and because the box is meant to be accessed this way (both locally
and remotely), a firewall is the best way to restrict telnet access.

--
Ascend Communications, Inc          Service & Support
support () ascend com
http://www.ascend.com/service

I've forwarded this to the ascend users group (ascend-users () bungi com) so
we can get Kevin Smith's (kevin () ascend com) and Matt Holdrege's
(matt () ascend com) opinion on this.

I have my own opinions on the problem.  The Pipeline family has always
been a very basic, barebones line of routers with a somewhat limited set
of functions.  They'll do NAT, RIP, etc. but all of them only allow you
two telnet sessions into the router and only one diagnostics session.
This was done to limit the resources that would be consumed so ram/cpu
wouldn't be burderend with tons of telnet sessions and/or diagnostic
sessions which can kill it's bigger brother the MAX, just like doing
debug all on a cisco will hose it.

But regardless, even if there was an idle timer on the authentication
mechanism, there are still a few problems.  One problem is that even
with a login timeout, you're going to have two telnet sessions max, which
is a limit placed most likely by the resources mentioned earlier.   So,
you can just keep opening telnet sessions as soon as the others die and
see if you can keep telnet access locked up.  Also, as of the 5.0A
versions of code (and possibly earlier) the ascend doesn't log telnet
connections to the syslog facility.  My maxen don't do it, and the
pipeline logs I've looked at don't do it.  They do log incoming calls,
call up, call down, and various other events, but not telnet access.
So, tracking down who's doing this would involve a sniffer, which might
not be a readily available tool to most people with pipelines as routers.

You're right though, the best way to handle the problem is by firewalling
or filtering out telnet access.  Guess this is a good selling point for
their Secure Access Firewall option.

Also, I was able to knock out 3 of my Ascend Maxen by repetedly telneting
to them.  Software version was 5.0Ap51, file ti.m40.  On a heavily loaded
max, I opened two successful simultaneous telnets and it died on the
third, while another max died at four.  I'm going to investigate further,
and I have no info on the 6.0.X versions of max code yet.

Joe Shaw - jshaw () insync net
NetAdmin - Insync Internet Services



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