On Mon, 29 Jul 2013 15:10:34 +0000 (UTC) "Artem S. Tashkinov" <[email protected]> wrote:
> Hello, > > Currently the Linux kernel disallows to start listening on a TCP/UDP socket if > there are open connections against the port, regardless connections status. > So even > if _all_ you have is some stale (i.e. no longer active connections pending > destruction) > the kernel will not allow to reuse this socket. > > Stephen Hemminger argues that this behaviour is expected even though it's 100% > counter productive, it defies common sense and I cannot think of any security > implications > should this feature be allowed. > > Besides, when discussing this bug on Wine's bugzilla I have shown that this > behavior not > only affect Windows applications running under Wine, but also native POSIX > applications. > > If nothing else is listening to incoming connections how can _old_ _stale_ > connections > prevent an application from listening on the port? Windows has no qualms > about allowing > that, why the Linux kernel works differently? > > I want to hear how the current apparently _broken_ behaviour, "The current > socket API > behavior is unlikely to be changed because so many applications expect it", > can be expected. > > Also I'd like to know which applications depend on this "feature". > > Imagine a situation, > > You have an apache server serving connections on port 80. For some reasons a > crash in > one of its modules causes the daemon crash but during the crash Apache had > some open > connections on this port. > > According to Stephen Hemminger I cannot relaunch Apache until the kernel > waits arbitrary > time in order to clean stale connections for its networking pool. > > I fail to see how this behaviour can be "expected". > > More on it here: > > https://bugzilla.kernel.org/show_bug.cgi?id=45571 > http://bugs.winehq.org/show_bug.cgi?id=26031 I understand your problem, people have been having to deal with it for 30 years. The attitude in your response makes it seem like you just discovered fire, read a book like Steven's network programming if you need more info. If you don't use SO_REUSEADDR then yes application has to wait for time wait period. If you do enable SO_REUSEADDR then it is possible to bind to a port with existing stale connections. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
