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→Dealing with Spam Email
A common and effective way to eliminate the volume of spam on the internet is for system administrators to shut down ''mail relaying''. Spammers often use programs which scan port 25 (the SMTP port) of systems connected to the internet looking for open relays. Having found an open relay they use this to send vast volumes of spam messages out. Such messages appear to originate from the system with the open relay (almost always a legitimate business with no connections to the spammer) thereby making it difficult to track down the spammer and minimizing the effectiveness of email blacklists.
== Web Based Security (SSL and TLS) ==
Today just about any form of activity can be performed via web sites, from applying for a loan or credit card to purchasing items with those credit cards. A surprising amount of personal and confidential data is now transmitted from user's browsers to web sites all over the world. Within a short time of all data being transmitted in plain text using HTTP on TCP port 80 it became clear that more secure ways of interacting over the internet were needed.
Secure Sockets Layer (SSL) is a secure protocol developed by Netscape Communications for the encryption of data transmitted over the internet. The Internet Engineering Task Force (IETF) adopted SSL in 1996 and named it Transport Layer Security (TLS). TLS is equivalent to SSL 3.0 (although TLS and SSL are not interchangeable).
SSL/TLS use cryptography to ensure that data transmitted between a browser and a web site is secured through encryption. The strength of this technology is that it essentially invisible to the user. The only sign that SSL/TLS is being used will the fact that a web site address begins with ''https'' rather than ''http'' and the presence of a small padlock icon on the status bar of some web browsers.
