While not intending to cross-post, after sending this question to the OpenSSH list on SecurityFocus, I noticed that the list is rather low traffic (the previous post was approximately 5 months prior). That being said, I decided to repost here as the issue will probably get more eyeballs (and will stand a better chance of being of use to others if answered):
The issue: I have a reverse SSH tunnel from an internal machine to a host in my DMZ which is set to launch at system boot and relaunch if the tunnel fails. However, when the tunnel is interrupted (for example, due to a network outage), it cannot reestablish due to the port on the DMZ host being in use. From my read of the OpenSSH mailing list archives and elsewhere, this appears to be because the port is in a TIME_WAIT state. This is fine: I can put in a sleep statement in the script that sets up the tunnel. However, this leads to two questions:1) Any idea how to determine what the TIME_WAIT interval is defined as on a particular Linux (or other) system? While I could just sleep for 5 minutes and be fine, it would be good to shave off as much time as possible. 2) While OpenSSH doesn't appear to support the "ClearAllForwardings" option, is there similar functionality whereby an auth'd connection can automatically teardown and recreate an existing connection it had previously established? A long sleep would probably be "good enough" but I'd prefer to handle the TIME_WAIT condition in a more efficient manner if possible. I appreciate any guidance or suggestions!