[laumars]

Sure, not a problem:

"A keep-alive is a small piece of data transmitted between a client and a server to ensure that the connection is still open or to keep the connection open. Many protocols implement this as a way of cleaning up dead connections to the server. If a client does not respond, the connection is closed.

SSH does not enable this by default. There are pros and cons to this. A major pro is that under a lot of conditions if you disconnect from the Internet, your connection will be usable when you reconnect. For those who drop out of WiFi a lot, this is a major plus when you discover you don't need to login again."

Source: http://www.symkat.com/ssh-tips-and-tricks-you-need

There's probably better sources out there, that was just one of the top results in Google as, if I'm honest, I'm not an expert on this either.

[bluecmd]

Devil is in the details, but the source actually talks against you here:

  This happens because your router or firewall is trying to clean up dead connections. It's seeing that no data has been  transmitted in N seconds and falsely assumes that the  connection is no longer in use.
 To rectify this you can add a Keep-Alive. This will ensure that your connection stays open to the server and the firewall doesn't close it.

In other words: What keep-alive does is that it prevents routers/middle-ware-boxes to forget that the connection exists in the first place. This is not needed on a clean internet connection where everything is treated as stateless and simple routing is everything that is done.

[laumars]

It also says: "if you disconnect from the Internet, your connection will be usable when you reconnect.". The same logic applies if you restart your network interfaces on the server.

I'm open to being proved wrong here, but as I've already said, only been doing this for several years now, so I'd need a counter argument to explain the mechanics of what's allowing the connection to reattach rather than "it's not possible" :)

edit: hmmm, re-reading the latter part of keep alive article I posted, it does seem to imply what your saying. So how come my SSH connections aren't nuked then? Is this just a property of TCP/IP (I'm not a networking guy so ignorant to some of the lower level stuff)

[bluecmd]

Yes, as long as both endpoints (TCP/IP stacks) keep their state it doesn't matter what stuff does between them. Interfaces being one of the things being between stacks. That is what allows for stuff like live application migration as long as you bring the TCP/IP state.

[laumars]

I see. Thank you :)