More and more critical applications have been migrated to websites now. Meanwhile, the security of these apps have become a major challenge to all kinds of institutions. Know yourself as well as the enemy, so that you can fight a hundred battles with no danger of defeat. Similarly, only by understanding the exploitable vulnerabilities exist in web applications and the attack methods adopted by web attackers, we can more effectively ensure the safety of our web apps.

For guy who wants to be a master of network (WAN/LAN, no matter it's black, red or white), without help of various off-the-shelf classical network utilities for multipurpose uses, I'm afraid your level will stay in the DOS era of last century forever. I mean, in that case, even it was you invented the whole Internet, you could not do anything interesting or exciting.

With the development of mobile devices and network, intelligent mobile phone has become a new paradise for hackers. Imagine, under this environment of everybody holds a smart phone nowadays, nothing is more active than the mobile phone viruses and the vulnerabilities' exploits of software and mobile network. Therefore, to understand and master some practical security tools seems necessary and meaningful.

Whenever your passwords should not be written on the paper and then put under the keyboard, caught in the pages of notebook, or even just recorded on the computer with Windows Notepad... In addition, the more and more passwords will become much easier to be forgotten over time. Therefore, we need a well-designed, reassuring password managing utility.

This computer security book on cryptography was published in 1995, but never hence miss such a classic work - because even in today 2015, it is still working. If you want to study cryptography, then do read Applied Cryptography written by Bruce Schneier.