On linux echo 20 > /proc/sys/net/ipv4/tcp_fin_timeout

saurik · on Nov 26, 2012

The question was not "how do you do it once you decide" but "how do you decide on such an arbitrary replacement".

Also: "Do not be confused by the /proc/sys/net/ipv4/tcp_fin_timeout config item. The FIN TIMEOUT is not the same as the TIMEWAIT length." -- http://www.stolk.org/debian/timewait.html

priestjim · on Nov 26, 2012

The value was picked heuristically after measuring through Ganglia and a set of CLI tools the average TCP dialog duration between a set of mobile devices and our database and then performing a set of tests with varying TIMEWAIT lengths. The 20 second period is a sweet (and round :)) spot with < 0.01% of packets / day arriving after FIN. It's a good approach all in all, since our expected payload packet set is extremely small (just 1 on broadband connections with large MTUs).

- Panagiotis Papadomitsos, Head of Infrastructure @ BugSense

krichman · on Nov 27, 2012

I was hoping it got chosen empirically. It's awesome that they were wise enough to not pick some theoretical best and calling it a day.