How I use autossh

autossh is nice little program that will auto restart ssh connections when they drop
This is extremely useful if you use ssh-tunnels a lot.

  • autossh is a program to start a copy of ssh and monitor it, restarting it as necessary should it die or stop passing traffic. The idea is from rstunnel (Reliable SSH Tunnel), but implemented in C.
  • Connection monitoring using a loop of port forwardings or a remote echo service.
  • Backs off on rate of connection attempts when experiencing rapid failures such as connection refused.

I have my raspberrypi at home using autossh to do a remote port foward of ssh to my server.

 

To set this up I created an account on my server I just for tunneling.
User called tunnel with the shell set to /bin/false
On the rpi I generated ssh-keys (with no password)

Toss the public key into the tunnel account of the remote servers  ~/.ssh/authorized_keys

now test it with out auto ssh:

root@rpi:~# ssh -N -R 3333:localhost:22 tunnel@server
the -N is for no shell; the -R is forwarding the rpi’s ssh’d to your remote server on port 3333
now from the server you can do  ssh user@localhost -p 3333   and login :D

 

Now for autossh!
i use autossh in cron; not _sure_ if that’s how its meant to be used… but it works very nicely
as roots , crontab -e
*/1 * * * * autossh -M 20001 -R 3333:localhost:22 -N tunnel@server
this will check the tunnel every minute, and if its not up it will bring it up

 

 

Its like a lazy mans vpn! :D

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