Lesson 11 Date: 4/17/2019

Linux Network Security

Linux System Administration

Examples of how systems get compromised Cracked, stollen and sniffed passwords SSH client with a sniffer on a multi-user system: reads user name, password and the destination host. SSH brute force attack guesses user credentials. Accounts with empty passwords and root privileges World writable files and directories can be used for planting trojans. SETUID and SETGID executables Trojans Stack overflow attacks on vulnerable services Worms

How systems get compromized Exercise: SSH brute force attack Exercise: Log check for login attempts Exercise: TCP wrappers Exercise: denyhosts Stack overflow Exercise with Stack overflow Package upgrades and verification Open Ports List exercise Closing Ports IP filtering firewalls (iptables) Building iptables rules Simple iptables script Exercises with iptables Port scanning exercises System Integrity Checks GNUtar exercises References Take me to the Course Website