RedHat Enterprise Linux AS4 commands and the locations of the most useful files

service - this command can be used to start stop or restart services properly, syntax is:
service xxx start or service xxx restart or service xxx stop where xxx is one of the services listed when you do a service --status-all

a similar utility, chkconfig allows you to turn services automatically on/off at boot. syntax is similar to above only:
service xxx on
or
service xxx off

lokkit - Redhat Enterprise Linux AS v4's firewall manager utility