TCP time_wait and port exhaustion for servers

William Herrin bill at
Wed Dec 5 18:58:58 UTC 2012

On Wed, Dec 5, 2012 at 12:09 PM, Ray Soucy <rps at> wrote:
> Like most web traffic, the majority of these connections open and
> close in under a second.  When we get to a point that there is enough
> traffic from users behind the proxy to be generating over 500 new
> outgoing connections per second, sustained, we start having users
> experience an error where there are no local ports available to Squid
> to use since they're all tied up in a TIME_WAIT state.
> Here is an example of netstat totals on a box we're seeing the behavior on:
> 481947 TIME_WAIT

Stupid question but how does 500 x 60 = 481947?  To have that many
connections in TIME_WAIT on a 60 second timer, you'd need more like
8000 connections per second, wouldn't you?

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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