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2. Accessing ports with dosemu

Beside ports that certain dosemu-subsystems need, the system administrator can allow access to specific ports. There are several things to consider:

2.1 System Integrity

To block two programms from accessing a port without knowing that the other programm does, this is the strategy dosemu takes.

2.2 System Security

If the strategy administrator did list ports in /etc/dosemu.conf and allow a user listed in /etc/dosemu.users to use dosemu, (s)he must know what he is doing.

2.3 Speed

For ports below 0x400, each process has a map af ports allowed to access. If a port is allowed, vm86() dosen't produce an exception. That way, dosemu has no way to log the values written to that port. To log the value, the port may not be in that map while inside vm86(). This produces an exception, and dosemu can decide on a per incident case what to do with that exception. But that is rather slow.


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