Security

Linux provides many tools that can arm a system administrator harden a system, making it less of a target.  This section talks about tools and techniques that can be used to protect your systems, services and data.

Blocking SSH Brute Force Attempts

Linux shell access is a very popular target.  SSH can provide egress into  a system with a weak password.  Once shell access is obtained, it is only a matter of finding some local system exploit to escalate privileges and own the system.   

If you ever see these entries in your /var/log/auth or /var/log/secure depending on your Linux distribution the you are the victim of a SSH brute force attack.   

IPTables Port Redirection

IPTables is a powerful tool that can be used for a variety of network based tasks.  In this example, I will show you how you can redirect TCP traffic destined for host and port on one system to another host and port on a completely different system.  You may be wondering about the utility of this feature and I am going to tell you that there is a lot.  Let's say you have moved a web server to another host, but the current host remains in place.  You want to send all the traffic from the old server to the new server. 

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