Licenses (Network Troubleshooting Tools)

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A.3. Licenses

Although some commercial software has been mentioned, this book has overwhelmingly focused on freely available software. But "freely available" is a very vague expression that covers a lot of ground.

At one extreme is software that is released without any restrictions whatsoever. You can use it as you see fit, modify it, and, in some cases, even try to sell your enhanced versions. Most of the software described here, however, comes with some limitations on what you can do with it, particularly with respect to reselling it.

Some of this software is freely available to some classes of users but not to others. For example, some software distinguishes between commercial and noncommercial users or between commercial and academic users. For some of the tools, binaries are available, but source code is either not available or requires a license. Some of the software exists in multiple forms. For example, there may be both free and commercial versions of a tool. Other tools restrict what you do with them. For example, you may be free to use the tool, but you may be expected to share any improvements you make.

You should also be aware that licensing may change over time. It is not uncommon for a tool to move from the free category to the commercial category, particularly as new, improved versions are released. This seems to be a fairly common business model.

I have not attempted to describe the licensing for individual tools. I am not a lawyer and do not fully understand all the subtleties of license agreements. Different licenses will apply to different organizations in different ways. In some cases, such as when encryption is involved, different countries have laws that impact licenses in unusual ways. Finally, license agreements change so frequently, anything I write could be inaccurate by the time you read this.

The bottom line, then, is that you should be sure to check appropriate licensing agreements whenever you retrieve any software. Ultimately, it is your responsibility to ensure that your use of these tools is permissible.