Linux Security, cont.

1. Turn off unnecessary services! (sendmail, portmapper, linuxconf, auth (pidentd), telnet, ftp, (x)inetd ?, ...)
   • Services run by rc scripts (scripts in /etc/rc.d/init.d/, services which are run are linked into /etc/rc.d/rc5.d/)
     • use service to turn on/off: service sendmail stop
     • use chkconfig, ntsysv, tksysv (control-panel) to turn on/off at boot time: chkconfig --del sendmail
   • Services run by (x)inetd (ftp,telnet,talk,time,etc...)
     • Generally can (should) turn off (x)inetd (which is an rc script service)
   • How do I know what services are running?
     • Use netstat or nmap (nmap may not be installed by default) to check which services are running