Practitioners of every profession on Earth use specialized tools in the performance of their duties. Doctors use diagnostic tests, stock brokers use technical analysis tools and carpenters use hammers and nails. It's no different for information security professionals. Every network administrator should have a basic toolkit on hand before tackling any job. In this tip, we take a look at a few essential components of that toolkit and provide examples of free tools that are available on the Internet.

When assembling your toolkit, consider having at least one of each of the following:

  • A packet sniffer allows you to examine network traffic at the byte level. You'll be able to monitor, capture and analyze traffic as it appears on the wire. This is especially useful when you're dealing with security threats that produce malformed packets or excessive traffic. It will also help you diagnose failed networking hardware. One commonly used free packet sniffer is the

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  • tcpdump package.

  • A port scanner such as Nmap enables you to scan networks and individual hosts and determine what services are running. These tools help you detect unauthorized systems and services. Nmap includes functionality that allows you to remotely identify the operating system and version running on a specific machine based upon fingerprint matching technology.

  • An intrusion-detection system (IDS) allows you to monitor a network for signs of malicious activity. If you're searching for problems on a network, you may wish to install a free IDS like Snort to look for known patterns of malicious activity.

  • Most system administrators groan at the thought of sifting through log files for precious tidbits of information. Log analyzers like Swatch (the "simple watcher") allow you to perform this tedious task in a much more efficient manner.

  • Vulnerability scanners like SARA (the Security Auditor's Research Assistant) enable you to seek out systems on your network that contain known vulnerabilities for easy patching.

  • Password crackers like Crack allow you to quickly scan a host for accounts with weak passwords and either disable them or force their owners to implement stronger passwords.

Enjoy these tools! They're just a few of the many great pieces of software put together by dedicated security professionals seeking to advance the state of the art.

About the author
Mike Chapple, CISSP, currently serves as Chief Information Officer of the Brand Institute, a Miami-based marketing consultancy. He previously worked as an information security researcher for the U.S. National Security Agency. His publishing credits include the TICSA Training Guide from Que Publishing, the CISSP Study Guide from Sybex and the upcoming SANS GSEC Prep Guide from John Wiley. He's also the Guide to Databases.

This was first published in August 2003

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