I'm going to be deploying a number of machines in the near future which will be behind routers. It won't be feasible to set up dynamic DNS on each router and port forwarding, so is there a way I can configure these machines to initiate a TCP connection to my computer and then have my computer initiate a SSH connection to the remote computer over that connection? IE:COMPUTER A OPENS TCP CONNECTION TO COMPUTER BCOMPUTER B OPENS SSH CONNECTION OVER THE EXISTING TCP CONNECTION TO COMPUTER ACOMPUTER B NOW HAS SSH CONNECTION TO COMPUTER AIs this possible, and if so, how can I do it? 
How can I configure a reverse SSH connection to the connecting computer?
ssh;tcp
In /etc/ssh/sshd for Computer B set:AllowTcpForwarding yesTCPKeepAlive yesFrom Computer A:$ ssh -R 2222:localhost:22 ip.of.computer.bFrom Computer B:$ ssh localhost -p 2222Note that 2222 is an arbitrary high-port number I picked. That port on Computer B will then be tunneled back through the SSH connection initialized on Computer A to port 22. If you have multiple machines you should use a different port for each machine.For your use case you will probably want to run this from a script so that you can make it a daemon and periodically try to re-connect if the link is dropped. You will probably want a special account with a shell of just /bin/true on Computer B to handle the incoming connections. You can then setup either a single key or multiple keys for each machine that are allowed to call home.On Computer A you might find the -n, -N and -T options useful to disconnect it from local input (so it can run in the background), not try to run any remote command, just open the tunnel, and not create a tty.Most normal methods of spawning a daemon don't work very well with setting up a network tunnel like this. A problem in network connectivity would make it try to beat the wall down to get through. A simple loop with a sleep to wait should do the trick. Ten minutes is a nice number because it doesn't flood the network and log files with attemps if there is a problem (like Computer B being offline) but it still gets you back in reasonably quick if the connection is droped.#/bin/shwhile true; do    sleep $((60*10))    ssh -nNT -R 2222:localhost:22 ip.of.computer.bdoneA script like that can be run launched on boot /etc/rc.local. Your first change to log into the machine will start about ten minutes after the Computer A boots.