Security: Securing X
(last edit: 2000-11-22)
                   Problem:
You don't want to logout X and the prompt everytime you leave your computer.

Solution
Install xlock from '/usr/ports/x11/xlockmore' . Now just type 'xlock' and a realy ugly 
screensaver is started which is locked with your login password. At the bottom of the screen
your .signature file is displayed.

But there is a security hole here!!!! When a person hits CTR+ALT+BACKSPACE x will be killed 
(including xlock) and this person will be at your prompt with you still logged in. A simple
'startx' will start x again and now you have bypassed xlock. Oke the apps/connections you
had open are killed but still...

You can solve this by starting x as follows:

user@host:~#exec startx

from the freebsd 3.3 man page:

"The exec family of functions replaces the current process image with a new process image"

When you start exec the old process wil be transformed to a new process. So if you start 
'exec vi' from an xterm the xterm-process will be transformed to a vi process. Kill your
vi and kill your xterm because the xterm process doesn't exist anymore

When you type a '$ps -axj' you'll see something like:

 USER    PID  PPID  PGID   SESS JOBC STAT  TT       TIME COMMAND
 user  39358     1 39358 8809c0    0 IWs+  v0    0:00.00 (sh)
 user  39404 39358 39358 8809c0    0 IW+   v0    0:00.00 (xinit)

PPID is the Parent Process ID

As you can see xinit, which is the program which starts x, has the same PGID as sh.

Situation without exec:

 USER    PID  PPID  PGID   SESS JOBC STAT  TT       TIME COMMAND
 user  39466 39465 39466 8a4f80    0 Is    p3    0:00.21 zsh
 user  41159 39466 41159 8a4f80    1 S+    p3    0:00.15 xterm

As you can see the PGID is different now.

See also the section Xautolock/xlock for more info.