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UNIX for Dummies Questions & Answers
plan
Post 10957 by Perderabo on Monday 26th of November 2001 10:14:22 AM
11-26-2001
Please don't try this. It can cause problems. The way it was done was to make .plan a named pipe and leave a program running that was writing to the pipe. The program would notice when a reader to the pipe existed and would start to run.
But if that program died, fingers would just block. If they were remote fingers resources would lock up until the system crashed. This was considered to be a denial of service attack. Most finger programs now will stat .plan and ignore it if it's not a plain file. So you probably can't do this anymore.
Here is a story that you probably won't believe...I know it's true and I can hardly believe it...
In my youth, I once decided to have a little fun with .plan. I set it to "Bus error(coredump)". I thought this was funny, but since I was the sysadm and people only fingered me to get my phone number, they just reported it to me as a bug.
So I upped the ante to "Trolleycar error (core ejected) Deleting all files in current directory...exporting this behavior to all reachable networks!". I felt certain that folks could figure out that this message was bogus... Then I got a call from a guy who said his officemate had just got that message and was racing to the computer room to yank all of the cables out of the system. 
I stopped him before he did any damage. Then I deleted my .plan and haven't had one since.
But if that program died, fingers would just block. If they were remote fingers resources would lock up until the system crashed. This was considered to be a denial of service attack. Most finger programs now will stat .plan and ignore it if it's not a plain file. So you probably can't do this anymore.
Here is a story that you probably won't believe...I know it's true and I can hardly believe it...
In my youth, I once decided to have a little fun with .plan. I set it to "Bus error(coredump)". I thought this was funny, but since I was the sysadm and people only fingered me to get my phone number, they just reported it to me as a bug.
So I upped the ante to "Trolleycar error (core ejected) Deleting all files in current directory...exporting this behavior to all reachable networks!". I felt certain that folks could figure out that this message was bogus... Then I got a call from a guy who said his officemate had just got that message and was racing to the computer room to yank all of the cables out of the system. I stopped him before he did any damage. Then I deleted my .plan and haven't had one since.|
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userlist
USERLIST(8) Finger-type Userlisting USERLIST(8) NAME
userlist - Userlisting of who's on your system. SYNOPSIS
userlist DESCRIPTION
This program simply gives you a listing of who is connected to your system. It is used primarily in the sorted listing of cfingerd, which utilitizes the same method of display for a more uniform output between systems. (It also made more sense to do it this way instead of having jumbled up display listings in sorted finger displays. Besides, it made more sense to do this than use finger. :) This program functions with the same types of things in mind that cfingerd does. If the user has a .nofinger file, their username will not be displayed in the userlisting. Example output is shown as: Username Real Name Idletime TTY Remote console username I'm real ... 9d 23:59 0 (remote.site.com) where it would display the user's login name, the user's real name, their idle time given in the format "dd hh:mm", their TTY, and their remote location (or where they're telnetting from). If the username is over 8 characters, the program will not search for their information in the passwd file, since it may be too long. Besides, it checks getpwnam, anyway. :) OPTIONS
-c Give standard CFINGERD (custom) output. -n List only people idle less than one day. ADDITIONAL
Although userlist is not required to run as suid root, it is a good idea. The reason is it checks each users' directory for a .nofinger file. If indeed that user has a .nofinger file in his/her directory, that user will not be shown in the userlisting. If you change the program to run as nobody.nobody, you are free to do so. But you will also show the users if they are online, regardless of whether or not they have a ".nofinger" file (as long as their directory is NOT world-readable.) CONTACTING
If you like this program, have any suggestions on how it could be modified, or have bug reports, please write to: khollis@bitgate.com. Your continued Public Domain support is appreciated! Thanks. SEE ALSO
cfingerd.conf(5), cfingerd(8), finger(1). cfingerd 1.4.2 29 August 1999 USERLIST(8)