15 Free Network Security Tools
The Internet is the world’s largest network which connects you to thousands of other unfamiliar networks. In that case the security of your network and system becomes essential as it provides both physical and information security to paths, links, and databases. There are many tools and resources available on the Internet to secure your network and help in executing your major tasks within a protected environment. 
Email Spam-Blocking Software
MailWasher- A powerful spam filter software that allows you to check and manage your e-mails before downloading them. It eliminates the spam by checking and stopping unwanted viruses and e-mails. It works with Outlook, Outlook Express, Incredimail, Thunderbird, Windows Mail, Gmail, Hotmail and every other email program.
Spamihilator- It examines the emails before downloading from the servers and delete unnecessary messages. It uses a Word-Filter that searches messages for known keywords. You can identify certain words and expressions and add them to the program.
SpamBayes- The project is working on developing a bayesian anti-spam filter, initially based on the work of Paul Graham. The major difference between this and other, similar projects is the emphasis on testing newer approaches to scoring messages.
Encryption Software
Ddcrypt- It is a small and fast utility tool that will help you in encrypting files and folders. It allows you to delete the files after the creation of the encrypted files. The files created by the software will create a file with an extension .ddc, that you can decrypt just browsing.
PGP – This tool offers basic PGP encryption capability for messages and files. It is acomprehensive data protection system that accurately reports to satisfy compliance needs. Whether sensitive data is stored on USB thumb drives, laptop computers, servers or mainframes, or sent to business partners via email or file transfer.
EyeMage IIE- This security tool allows you to securely encrypt any file or text into a bitmap image. Using this you can easily hide photos in photos, zip files in images and Word documents in diagrams then send them.
Intrusion Detection (IDS) and Prevention (IPS) Software
Snort- It is an open source network intrusion detection system that allows you to do traffic analysis and packet logging on IP networks. It can perform protocol analysis, content searching/matching and can be used to detect a variety of attacks and probes, such as buffer overflows, stealth port scans, CGI attacks, SMB probes, OS fingerprinting attempts etc.
AIDE (Advanced Intrusion Detection Environment) - It creates a database from the regular expression rules from the config file. Once this database is initialized it can be used to verify the integrity of the files. It has several message digest algorithms (md5,sha1, rmd160, tiger, haval,etc.) that are used to check the integrity of the file.
Prelude –Another innovative Hybrid Intrusion Detection system which collects normalizes, sorts, aggregates, correlates and reports all security-related events independently. 
Port Scanner Software
SuperScan- It is a TCP port scanner that includes a variety of additional networking tools like ping, trace route, HTTP HEAD, WHOIS etc. Its features include TCP SYN scanning, UDP scanning, HTML reports, built-in port description database; Windows host enumeration, banner grabbing etc.
Shields Up- It alerts you whenever your ports is opened through their firewalls or through their NAT routers. The utility can scan the most common file sharing ports, as well as all service ports.
Firewalls.com Port Scan – It is a free port scanner which is does simple yet informative web based scan. The results are accurate but in no way reflect what a complete network scan can do.
Anti-virus Software
Clam Antivirus –This is a Free Antivirus for Microsoft Windows NT/98/Me/2000/XP/2003. It features include high detection rates for viruses and spywar, scanning scheduler, right-click menu integration to Microsoft Windows Explorer.
McAfee Stinger – Another stand-alone tool helps in detecting and removing specific viruses. It is not a substitute for full anti-virus protection, but rather a tool to assist administrators and users when dealing with an infected system.
Avast Home Edition- It is a free antivirus software for home noncommercial use. It scans for viruses, worms and Trojans on disk, CDs, in E-mail, IM and P2P. This small, fast and reliable tool offers you updates of virus database twice a week.
Hope you would utilize these tools to protect your network from all kinds of internal and external security threats. Please provide us your feedback and suggestions on the same.
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