Preventing Idle in telnet, security, and bg.

[John E. Davis]

Hi,

   I have a vt320 that I use all the time.  When I logon to our system, I
start up a process in the background that sleeps for a minute, checks my
mailbox for newmail then just before going back to sleep, it sends the time
and number of mail messages to my vt320 status line.  It has worked fine so
far with no problems.

   However, sometimes I forget to kill it before I logout.  I was wondering
what is the best way to put it into the background so that when I logout, it
dies?  I wrote the program in c, if this helps.

   A friend of mine once told me that when he logged on, it started writing to
his terminal.  Apparantly, I was once attached to that tty and left it
executing when I logged out.  I really do not understand this particular
occurence at all.  Perhaps some kind soul will tell me what happened.

   On another subject,  One person on our system has in his home directory an
executable file called 'ls'.  Here it is:

#! /bin/sh
/bin/ls -FC
echo `whoami` `hostname` `tty`  `date` >> public/log
exit 0

What happens, is if someone steps into this directory and types 'ls' this
thing takes his picture.  In principle, he could add a few more lines to copy
and delete mail, etc...  Although this 'ls' is harmless, it is conceivable
that great damage could have been done. Is this considered a security problem?
I do not advocate snooping around the system, however if one is new as I am to
the unix world, then one can benifit by seeing what other people have.  For
example, by looking in other .emacs files, I learned alot of things about
setting up the arrow keys for my terminal.  Besides, isn't any file with world
read access considered to be in the public domain?
--
John

  bitnet: davis at ohstpy
internet: davis at pacific.mps.ohio-state.edu