MAC addresses, hostnames, and DHCP

[Paul Lussier]

kevin_d_clark at comcast.net (Kevin D. Clark) writes:

> 2:  TCP doesn't have any keepalives by default, and when it does, the
> time period for these are typically in the range of *hours*.

[...]

> 8:  OTOH, if the SSH connection really is timing out after exactly two
> minutes but the state of the connection wasn't in the TIME_WAIT state
> in the preceeding seconds, this suggests to me that there is more of an
> application-layer timeout going on here, because TCP will almost
> certainly retry for more than two minutes.  After all, it is a general
> purpose reliable transport protocol.

FWIW, I just took my entire network down yesterday for close to *9*
hours.  At the end of our massive re-wiring,de-rats-nesting excercise,
I went back to my desktop and unlocked the screen.

Not one of my screen sessions, nor one my 70+ shell sessions on any of
the 30-40 different hosts across the network was lost.  My desktop was
most certainly *not* connected to the network for this entire 9 hour
period.  So, Kevin's right wrt the TCP time out being in the range of
hours!

OTOH, I typically have my ssh connections to worked dropped by the
remote system after some (yet to be determined) time out period.
However, I'm almost certain this is an SSH or firewall configuration
issue, since it's only the _inbound_ connections which time out.  My
ssh connection from work to home typically stays up until our electric
company begins dropping packets ;)
-- 

Seeya,
Paul