Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cos!hadron!jsdy
From: jsdy@hadron.COM (Joseph S. D. Yao)
Newsgroups: comp.sys.mips
Subject: Re: login and syslog question.
Message-ID: <905@hadron.COM>
Date: 17 Aug 90 16:27:48 GMT
References: <24581@boulder.Colorado.EDU>
Reply-To: jsdy@hadron.UUCP (Joseph S. D. Yao)
Organization: Hadron, Inc., Fairfax, VA
Lines: 37

In article <24581@boulder.Colorado.EDU> hartzell@beagle (George Hartzell) writes:
>I have two related problems/questions.  ...
>	   ...  I have 48 serial lines strung out through a large
>building (almost certainly out of rs232 spec).  ...
>turned off login/getty tries to log in "people" with names like
>"mkmkk[m[".  ...

Tying a resistor across two leads of an EIA RS-232 serial line is a
very bad idea.  Your EE friends know about "ringing" and things that I
don't really understand, but they don't know the EIA standard.

DISCLAIMER: I'm a "software engineer" (whatever that is), so I tell
people I don't know anything about hardware so they don't expect me
to fix the filthy stuff.  What I know, I've garnered by research and
experience.

Your best fix is to use cables that tie the DTR (Data Terminal Ready)
lead of your remote terminal or terminal emulator to the DSR (Data Set
Ready) lead of your serial port.  Then tell your serial board (if you
can) that this is a "modem" port, and so should be ignored while the
DSR lead is not on.  Many people figure they are winning by tying
together pins 1 (FRAME ground) and 7 (SIGNAL ground), which is quite
illegal by the standard, or leaving pin 1 off entirely; and by putting
a lump of solder over pins 4, 5, 6, 8, 20, and 22, to keep the line up
all the time.  What they win in copper savings, they lose in aggravation
such as yours.  The DEC 1976 Peripherals Handbook is the last one that
had a nice diagram of which pin should be crossed with what in a "null
modem" - type cable; I try not to remember these things any more.

	Joe Yao				jsdy@hadron.COM
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