OSEC

Neohapsis is currently accepting applications for employment. For more information, please visit our website www.neohapsis.com or email hr@neohapsis.com
 
Re: Closing policy connections to smtp causes smtps in CLOSE_WAIT

From: Victor Duchovni (Victor.DuchovniMorganStanley.com)
Date: Sun Apr 02 2006 - 15:14:47 CDT

On Sun, Apr 02, 2006 at 07:47:09PM +0200, Robert Felber wrote:

> Hello,
>
> I'm trying now since 4 days to solve an annoying issue.
>
> smtpd opens a connection to a policy server.
> Communication is done, attributes shared, actions done.
>
> Now smtp leaves the connection open, the policy server is fine
> with that.
>
> Now if either the user, or the policy server decides to close
> a idle connction, we have smtps in CLOSE_WAIT state.

Unlike SIP, TCP requires both sides to close the connection before
the state is completely released.

> The smtps are hanging in a flock.

Idle SMTP servers don't do anything until they get an SMTP connection.

> On BSD it seems, that the connection will be closed and reopened
> as soon if a new policy request is requested,

When the SMTP server discovers that the connection is closed, it
will reconnect.

> on linux 2.6 it seems to hang.

Show a system call trace? Sounds like a Linux bug. Is a TCP policy
service, or a unix-domain socket policy service?

> I've tried shutdown(2) (with argument 2) as well as close()
>
> How can I ensure that an idle connection may not only be closed
> by postfix.
>

TCP connections are closed one end at a time. The until the
other end sends its FIN the connection is still open, though
data transfer may not be possible (will result in a RST).

--
        Viktor.

Disclaimer: off-list followups get on-list replies or get ignored.
Please do not ignore the "Reply-To" header.

To unsubscribe from the postfix-users list, visit
http://www.postfix.org/lists.html or click the link below:
<mailto:majordomopostfix.org?body=unsubscribe%20postfix-users>

If my response solves your problem, the best way to thank me is to not
send an "it worked, thanks" follow-up. If you must respond, please put
"It worked, thanks" in the "Subject" so I can delete these quickly.