Ulrich Drepper noted a difference between the Linux connect(2) man page and the POSIX specification. The former states, "connectionless sockets may dissolve the association by connecting to an address with the sa_family member of sockaddr set to AF_UNSPEC." The latter reads, "if address is a null address for the protocol, the socket's peer address shall be reset." Ulrich explained that he preferred the description in the Linux man page, but the Linux kernel seems to actually follow the POSIX specification, "is this functionality which got lost over time? Or is the man page wrong and this never was the case? Is this a worthwhile change?"
Alan Cox noted, "we got it from the 1003.4g draft socket specification if I remember rightly." David Miller suggested, "the whole AF_UNSPEC thing I'm almost certain comes from BSD, which has behaved that way for centuries." Alan concurred, "its entirely plausible that [the 1003.4g draft socket specification] got it from 4BSE." Ulrich concluded, "I guess I'll just go ahead and file a problem report with the spec. Maybe the Unix vendors will test their implementations and provide feedback."