Forwarded ports: delay after last close before exiting

[John Hardin]

I use fetchmail+ssh (soon to be openssh) to retrieve mail for several
accounts. The setup for this forwards a couple of local ports to the
mail server POP and IMAP ports, then sleeps. Nothing fancy.

If the first poll has a lot of messages, enough that it extends beyond
the end of the sleep, then when it completes ssh sees no activity on the
forwarded ports and exits. This prevents subsequent polls in that run
from connecting to the mail server and retrieving mail.

Rather than having each poll build its own tunnel, I'd like to add some
code to openssh be able to specify "If the activity on forwarded ports
ends, wait N seconds before exiting" - on the assumption that it would
wait long enough for the next poll in the run to start and open a
forwarded port.

First off, can anybody say "that won't work"? I haven't dug too deeply
into the code yet so I don't know if there are more issues than simply
adding a timer and re-check to the "wait for forwarded ports to
complete" loop.

Second, I want to specify the wait duration on the command line. Since
ssh is supposed to be a drop-in replacement for rsh et. al., the
selection of a letter for this is not unconstrained. Would adding the
option "-W delay" break anything besides command-line compatibility with
regular ssh?

Thanks for your input.

--
        John Hardin
        Internal Systems Administrator
        Apropos Retail Management Systems, Inc.
        <johnh at aproposretail.com>