Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!pasteur!ucbvax!RUDY.FAC.CS.CMU.EDU!Rudy.Nedved From: Rudy.Nedved@RUDY.FAC.CS.CMU.EDU Newsgroups: comp.protocols.tcp-ip Subject: Re: Unix TCP connectivity problems Message-ID: <8902030504.AA05796@ucbvax.Berkeley.EDU> Date: 2 Feb 89 17:07:38 GMT References: Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 18 Mark et al, The CMU version of the pseudo terminal (pty) driver for 4.3BSD based Unix (or for Mach Unix) has the concept of detached jobs. For this reason, it is not a big deal to lose a network connection for Mach systems (assuming you are running the CMU modified telnet daemon which uses the CMU pty driver). For programs that use the network, you can detect a problem with an aborted connection by checking errno which is documented in intro(2). You will get an errno of ENETUNREACH, ENETRESET, ECONNABORTED or ECONNRESET (most likely). But for general transparent network support of terminal sessions, the concept of a detached terminal is needed. We have had this concept since 4.0BSD Unix before the days of TCP (we used it for Xerox BSP/PUP 'Chat' connections). -Rudy