17.10 Summary

The ioctl commands that are used in network programs can be divided into six categories:

• Socket operations (Are we at the out-of-band mark?)

• File operations (set or clear the nonblocking flag)

• Interface operations (return interface list, obtain broadcast address)

• ARP table operations (create, modify, get, delete)

• Routing table operations (add or delete)

• STREAMS system (Chapter 31)

We will use the socket and file operations, and obtaining the interface list is such a common operation that we developed our own function to do this. We will use this function numerous times in the remainder of the text. Only a few specialized programs use the ioctl operations with the ARP cache and routing table.