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Re: FTP keep alive connection

From: Jamie Lokier <>
Date: Wed, 7 Nov 2007 18:44:44 +0000

Daniel Stenberg wrote:
> On Wed, 7 Nov 2007, Patrick Monnerat wrote:
> >SO_KEEPALIVE (associated with keep-alive timeout adjustments in the
> >firewall and/or client OS) may create transparent activity on the control
> >connection without disturbing the FTP protocol itself.
> Yes, assuming you can make it send keepalive packets more often than the
> timeout time is set to in the firewall. If I recall things correctly,
> SO_KEEPALIVE default is something like two hours and I believe there are
> operating systems on which changing that time is hard.

For the benefit of those operating systems, you could send NOOP, and
_if_ a response is received _during_ data transfer (meaning the server
does process commands), then send more... However it would be quite a
complication to the client code, risk upsetting some servers, not help
with some servers, and probably not worth the effort.

-- Jamie
Received on 2007-11-07