Reproduced with permission from Daniel Miessler

Tcpdump is the premier network analysis tool for information security professionals. Having a solid grasp of this über-powerful application is mandatory for anyone desiring a thorough understanding of TCP/IP. Many prefer to use higher level analysis tools such as Ethereal Wireshark, but I believe this to usually be a mistake.

In a discipline so dependent on a true understanding of concepts vs. rote learning, it's important to stay fluent in the underlying mechanics of the TCP/IP suite. A thorough grasp of these protocols allows one to troubleshoot at a level far beyond the average analyst, but mastery of the protocols is only possible through continued exposure to them.

One of the most important aspect of communication should be confidentiality, that is especially true when you are a lawyer or a notary and you need to deal with your customer's privacy.

As you should know sending an e-mail is like sending a postcard, therefore confidentiality is lost by the very nature of e-mail communication. That is because your e-mail are hoping from outgoing mail servers to switches and networks, then reaching other isp incoming mail servers and god forbid if unencrypted wireless access points were not used along the links. Anywhere along these hops can anyone equiped with freely available sniffer tools get access to any unencrypted private data. Scarry, isn't it?

Hopefully there are many easy to apply solutions that allows you to get the full benefits of e-mail without the disavantages.