AutoSSH reverse tunnel service config for systemd

autossh-jump-rtunnel.service

[Unit]
Description=AutoSSH reverse tunnel service for jump.you.io 100022 -> 22
After=network.target

[Service]
Environment="AUTOSSH_GATETIME=0"
ExecStart=/usr/bin/autossh -M 0 -o "ExitOnForwardFailure=yes" -o "ServerAliveInterval 30" -o "ServerAliveCountMax 3" -NR 10022:127.0.0.1:22 [email protected] -i /home/root/.ssh/id_rsa

[Install]
WantedBy=multi-user.target

Place this file at:

/etc/systemd/system/autossh-jump-rtunnel.service

Also don't forget to generate a key-pair for root and put the public key in the authorized_keys file on the jump box.

My inspiration for this reverse tunnel came from the standard tunnel in this example:

• https://www.everythingcli.org/ssh-tunnelling-for-fun-and-profit-autossh/

Looks like for this to work after a restart the following lines need to be added to to the ~/.profile file:

ecryptfs-mount-private
cd "$HOME"

• http://askubuntu.com/questions/115497/encrypted-home-directory-not-auto-mounting
• https://stephen.rees-carter.net/thought/encrypted-home-directories-ssh-key-authentication

To enable to service unit in systemd do the following:

$ sudo systemctl daemon-reload
$ systemctl start autossh-jump-rtunnel.service
$ systemctl enable autossh-jump-rtunnel.service

I've munged something based on this, though I'm using /root/.ssh/config to manage most of the connection options. I ran into some trouble because I had left the -f option on the autossh command I'd been running manually before. Removing that fixed it. My line is ExecStart=/usr/bin/autossh -M 0 -NT tunnel. I have this all set up because I am tunneling through a bastion host to get to the actual machine I want to port forward from.

As https://unix.stackexchange.com/a/379991/47775 mentioned you could change the After target with network-online.target