illumos gate

TCP keepalive is a useful mechanism, but figuring out how to configure it is non-trivial. getsockopt(3SOCKET) describes SO_KEEPALIVE, but doesn't talk about the various related options like how often probes are sent and how long they can be outstanding before the connection is terminated. In fact, the default is two hours, which seems less than useful for many applications, so configuring it is important.

getsocket(3SOCKET) does reference tcp(7p) in the "SEE ALSO" section, and that man page does describe the socket options TCP_KEEPALIVE_THRESHOLD, TCP_KEEPALIVE_ABORT_THRESHOLD, and the more portable parameters TCP_KEEPIDLE, TCP_KEEPCNT, and TCP_KEEPINTVL.

I think it would help a lot if the existing paragraph about SO_KEEPALIVE in the getsockopt(3SOCKET) page had a sentence like this:

"Protocol-specific parameters that determine how often these messages are transmitted and when connections are terminated by this mechanism are documented in tcp(7p)."