Help! Telnet is broken under Ultrix 4.1

[Steven Winikoff]

All of a sudden users can no longer use telnet to connect to Alcor,
our DECsystem 5500 running Ultrix 4.1.  

Telnet out *from* Alcor to other systems works.

Telnet from any system *to* Alcor fails in the following way, even
when I try it from Alcor to itself:

   Trying...
   Connected to alcor.
   Escape character is '^]'.
   Connection closed by foreign host.

Telnet to other ports on Alcor works (eg # telnet Alcor 25).

When telnet fails, telnetd leaves a core dump in /etc.  (I don't know
enough about dbx or core dump formats to be able to learn anything
from this.)

Telnet used to work properly.  I don't know exactly how long it's
been broken, but I learned of the problem on June 19th.

On June 17th I had installed the DECnet/Internet gateway (using
# setld -c DNPINETGW400 INSTALL).

On June 18th I'd modified our /etc/hosts file.

However, editing /etc/inetd.conf to use telnetd instead of telnetd.gw
does NOT solve the problem.  Neither does restoring the previous
/etc/hosts.

I've reached the limit of my knowledge of telnet and IP configuration.
I have a service call in to the DEC software hotline, but so far they 
too have been unable to help.

Does anyone know what's going on?  Help!!!

Thanks in advance,

  - Steven

------------------------------------------------------------------------
Steven Winikoff                                 smw at alcor.concordia.ca
Software Analyst
Dept. of Computing Services
Concordia University                            voice: (514) 848-7619
Montreal, Quebec, Canada                               (10:00-18:00 EST)