How to start the echo service on OSX Mountain Lion to respond to autossh monitoring

Question

I have the following two machines :

Machine A. OSX Machine which will act as the SSH server
Machine B. An SSH client connecting to the above using autossh

autossh allows persistent, self-healing connections to be made and restarts the child ssh process if it exited abnormally (the man page has details about what 'abnormal' means). Specifically, I am interested in allowing scenario #4 to work:

Periodically (by default every 10 minutes), autossh attempts to pass traffic on the monitor forwarded port. If this fails, autossh will kill the child ssh process (if it is still running) and start a new one

Questions:

1. What is the recommended monitoring approach with autossh? Would it be monitoring on specific ports or using the echo service ? Or would it be to rely on OpenSSH's ServerAliveDelay so that ssh connections exit timely and disable autossh monitoring altogether?

2. If it's the latter, how do I start the echo service on osx? From the wiki page of inetd :

As of version Mac OS X v10.4, Apple has merged the functionality of inetd into launchd.

Therefore, how do I use launchd to start the echo service on osx Mountain Lion?

Answer 1

I would suggest that you stick with ServerAliveDelay and ServerAliveInterval, both of which can be specified inside a local ssh_config file. This will obviate the need for either a monitoring port or the use of the echo service, and will allow the ssh client to handle graceful exits while enabling autossh to restart lost connections.