Christof Meerwald <cme...@cmeerw.org> writes: > On Sun, Aug 28, 2016 at 02:13:34PM +0200, Tomasz Sterna wrote: >> W dniu 27.08.2016, sob o godzinie 14∶55 -0400, użytkownik Greg Troxel >> napisał: >> > should jabberd2 force TCP keepalive on? >> I'm not sure whether it is possible. >> At least on Linux it is a system-wide setting and requires root to >> change. > > Are you sure? There appear to be some socket options that can be set > for each socket: > > http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/#setsockopt
I'm not running Linux, so we're talking more or less about what POSIX specifies for the BSD sockets interface. But, that page describes in the SO_KEEPALIVE case exactly the traditional BSD socket option for keepalive, which I suspect dates from about 4.2BSD but my memory of the late 80s is now a bit fuzzy. So yes, I meant to have a way to enable keepalive via SO_KEEPALIVE on all sockets. But that's not really the right thing. Tomasz's point about Linux and system-wide setting is probably about what the default value is if a program doesn't ask for keepalives. OS X has a sysctl for this. NetBSD doesn't; it's up to the program, as it was historically. On the system in question, it is surely behind a buggy firewall. However, that's beyond my control. It's interesting that this doesn't show up, because I would expect the mobile to lose the data connection and fail to close the TCP connection fairly often. Arguably I have a system-wide problem, not a jabber problem. But still, given that clients just vanish, it seems like there should be some mechanism for connections to get cleaned up. I will check out the application-level keepalive. What I think I want is that for a connection from a client, if there has been no traffic in or out for 24h, to send a space. That will break the stale connections after a day, and it should not cause any additional traffic on real connections. For now I can just send a keepalive every 24h, and that's close enough.
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