Problem with telnet on Sun4/280 OS4.0

[David Pipes]

I have been having a recurrent problem here for the last few weeks, and
have been unable to get a handle on what is going on.  Perhaps some of you
may be able to enlighten me.  I have a Sun4/280 running 4.0 attached to a
local Ether- net which also serves several Vaxen and other Suns.  After a
few days of uptime, telnet starts to behave strangely.  It will stop
echoing characters, and will only take <ctrl-j> as a return character.
This happens to users coming over the Ethernet TO the Sun.  At first, it
only happens to one terminal, then it begins to affect more and more,
until no one can get in (usually about a day after it starts.)  I have
been rebooting to cure this.  

What type of problem could cause these symptoms?  I have been unable to
correlate it with use of any of our home-grown programs, with the
exception of one cpu and vm intensive program which runs for days at a
time.  But I can't see why it should affect telnet, as it is not
communications software and makes no use of ports.  I have checked that
the inetd daemons are up, I have tried restarting them, I have verified
that the usual processes are all running.  The system is configured in
these aspects identically to another which does not exhibit this problem.
Also, since the system ran fine earlier under 4.0, I surmise that it is
one of our programs under development.  But what kind of problem could
cause this?  I am at a loss as to what to tell people to look for in their
code.  Thanks for any suggestions; email welcomed. 

pipes at nssdca.gsfc.nasa.gov             David Pipes | | Vox: (301) 286-2248