Lesson 11

Date: 4/17/2019

Linux Network Security

Linux System Administration

Exercise: Using GNUtar for file system consistensy check
Downloaded file openssh-4.4p1.tar.gz:

wget http://linuxcourse.rutgers.edu/lessons/security_remote/Downloads/openssh-4.4p1.tar.gz

Unzip and untar the archive as root

sudo -s
gunzip openssh-4.4p1.tar.gz
tar -xvf openssh-4.4p1.tar

Consistency check:

tar -df openssh-4.4p1.tar openssh-4.4p1

It should show you nothing since the archive contains files with identical attributes.
Edit file openssh-4.4p1/ChangeLog and create a new line in it. Run the consistency check again:

tar -df openssh-4.4p1.tar openssh-4.4p1

See the results: 'Mod time differs', 'Size differs'

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