It's a Berkeleyism. It's not TCP, it's old Berkeley Sockets semantics. [...] Linux does support it, with the "shutdown(2)" call. The shutdown(2) system call wa

It's a Berkeleyism. It's not TCP, it's old Berkeley Sockets semantics. [...] Linux does support it, with the "shutdown(2)" call. The shutdown(2) system call was added to BSD on January 8th, 1983: https://svnweb.freebsd.org/csrg?view=revision&revision=10208 https://svnweb.freebsd.org/csrg?view=revision&revision=10208 So... Berkeley Sockets supported this a bit more than 8 years before Linux even existed. This is totally not a Berkeley Sockets problem.