From: utzoo!decvax!harpo!eagle!mhuxt!mhuxj!mhuxa!houxm!hogpc!houti!ariel!vax135!cornell!uw-beaver!jim
Newsgroups: net.bugs.uucp
Title: Login delay increases chances of getting connected
Article-I.D.: uw-beave.520
Posted: Fri Apr 22 07:45:49 1983
Received: Sun Apr 24 07:02:23 1983

This is not really a bug in uucp, but in 4.1bsd getty.  It is a long
story, so you may want to skip to the end of this message if you aren't
interested in grungy details.

The folks at Berkeley apparently have all their terminals ports wired
up to ignore DCD and assume that the terminal is always ready.  This
means that if you unplug a Berkeley terminal, the system still thinks
there is a terminal connected to the line, and it will send a "login:"
prompt down the disconnected line.  The problem with this is that an
unconnected line of sufficient length will "ring", and the login prompt
will echo back to the computer.  The computer will see the prompt and
echo it right back down the unconnected line.  You end up with a steady
stream of characters in and out the port, and a steady stream of dying
and restarted gettys, which puts a big load on the system.

Berkeley's "solution" to this problem was not to connect up DCD, but
rather to put a 1 second delay into getty after displaying the prompt
and before turning on echoing.  It flushes any characters received
during the delay.  Not only is this confusing to the users, it is also
confusing to uucp, which tries to send the login name right after it
sees the login prompt.  The login name gets dropped by the one second
delay.

I have countered this by putting my own one second delay into uucp
after getting the login prompt.  When I did this, my percentage of
failed logins dropped from 30% to 5% (actual figures, taken from
LOGFILE -- at the time, all our neighbors were 4.1bsd sites).

The standard uucp does not support delays, unfortunately, but there are
a lot of modified conn.c's floating around that do.  Our L.sys line now
look like this:

	blah blah login: \duucp word: uucp

In our case, the "\d" provides the one second delay.  Alternatively,
you could modify conn.c to always put in a delay before it sends
anything.