This section describes some of the tools and packages available on the Internet that you might find useful in maintaining security at your site. Many of these tools are mentioned in this book. Although this software is freely available, some of it is restricted in various ways by the authors (e.g., it may not be permitted to be used for commercial purposes or be included on a CD-ROM, etc.) or by the U.S. government (e.g., if it contains cryptography, there may be constraints on export or use in certain locales). Carefully read the documentation files that are distributed with the packages. If you have any doubt about appropriate use restrictions, contact the author(s) directly.
Although we have used most of the software listed here, we can’t take responsibility for ensuring that the copy you get will work properly and won’t cause any damage to your system. As with any software, test it before you use it!
Some software distributions carry an external PGP signature. This signature helps you verify that the distribution you receive is the one packaged by the author. It does not provide any guarantee about the safety or correctness of the software, however.
Because of the additional confidence that a digital signature can add to software distributed over the Internet, we strongly encourage authors to take the additional step of including a standalone signature. We also encourage users who download software to check several other sources if they download a package ...