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Using a for loop to examine a series of IP Addresses to use in a firewall script to block Zombie networks.

If you want to repeat a task more than one time, then you will be interested in loops. A loop will provide a way for you to perform that task with just one set of code.

The find command can be used to execute a command based on the data that is located with the initial find command. This provides a powerful alternative for manipulating the data you retrieve.

Dovecot 2 has new features, including security enhancements that administrators may want to use on CentOS. However, this version of Dovecot is not in the repository so you will need to install several additional packages.

The find command can use multiple expressions to enable complex searches which permit multiple criterion in the search. This feature greatly enhances the ability for creating precise searches.

Hotot is a lightweight, python-based, desktop twitter client I tried on my Linux Mint 10 GNOME desktop. I found Hotot to include many features you’d expect in a desktop client and a few you may not.

An advanced Nagios class, taught online by Mike Weber of CyberMontana Inc, has been scheduled for April 2011.

One of the most powerful options you can use with find is time criteria such as modified time, accessed time or changed time. Understanding how to use these elements will provide more effective searches.

The first of the bashshell.net "5 Days of find" series, this tutorial breaks down the basics. With the Linux find utility, you can perform powerful searches on just about any criterion you can think of, and then, from the same command-line entry, invoke another utility to do whatever you need to do with the results.

You have built a rock solid firewall, tested it with nmap scanning for ports that were open, locked down SSH with port knocking, restricted outgoing ports with iptables, setup psad to block attacks, and tcp_wrappers to limit access so you are set right? Well, not exactly....

This example shows how to use a Bash shell script to parse multiple logs for text strings and create a report.

The Linux utility awk can create output redirection for data you want to save and it can use input redirection from commands or respond interactively with users.

awk may be used to count instances and also sum columns for reports. Often it is useful to use awk scripts for the output so that it can be formatted to your needs.

awk allows you to change the fields separators so that you can use on a various kinds of files. You can also use multiple field separators on one file.

Sometimes you will need to create service checks using the MIBs that you can discover with snmpwalk. This tutorial will show you the process of creating service checks for a Cisco router manually.

The awk file can be modified to include a BEGIN section and an END section that allows you to perform tasks before and after the records are processed.

Using awk scripts expands the possibilities with awk and provides an easy way to repeat searches on a number of files.

When you use awk with operators levels, comparisons and ranges can be part of the data search.

The mail server can increase speed by placing a caching-nameserver on the mail server itself. This provides recursive lookups and a cache for the mail server to work with. The caching-nameserver does not require much resources and is easy to install.

By performing these basic commands you will begin to see the power and flexibility of the Linux utility awk. This exercise is designed to start you down the path of using awk.