Please Help.

I am new to linux Os.

I have a linux box that is on a LAN and also allows dial-in.

I want to disable the httpd from running on my linux box and also prevent double logging( a user logging twice from different machine at the same time).

thanks.
Adun

Depending on what distro your using, find the rc script usually in /etc/rc.d and either remove or edit the file httpd starts with. To manually stop it running you can do a as root:

apachectl stop

As trickykid said disabling a service is somewhat distribution dependent but the command
  rm /etc/rc?.d/S??httpd
or
  rm /etc/rc?.d/S??apache
ougth to do it. It will also suffice to rename the file(s) instead of removing them. In that case you want to change the capital S to something else; e.g. a low case s.

Disabling multiple log in is a bit trickier as this is not a normal thing to do; one trick could be to check if the user is already logged in with the help of the `who` command in the users .profile file and then force an exit. Why do you wnat to do it?