The kppp Handbook
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# 8.2. kppp has the SUID bit on. What about security?

Itīs virtually impossible to write a dialer without the SUID bit, that is both safe and easy to use for unexperienced users. kppp addresses the security issues with the following strategy:

- Immidiatly after program start, kppp forks.

- The master process (which does all GUI stuff, user interaction and such) drops the SUID state afterwards, and runs with normal user privileges.

- The slave process keeps itīs privileges, and is responsible for all actions that need root privileges. To keep this part safe, no KDE/Qt library calls are used here, just simple C library calls. The source code for this process is short (around 500 lines) and well documented, so itīs easy for to check it for security holes.

- Master and slave process communicate with standard UNIX IPC.

Many thanks to Harri Porten for writing this excellent piece of code. I thought it was impossible - he made it within a week.

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