How Can a Reverse-Ssh Connection Be Launched and Maintained on Ubuntu Boot with Systemd?
My Mum Has a Wee Laptop That Needs, When It Boots Up, to Reverse-Ssh Connect Itself to a Server (So I Can Help out When Needed). I'm Struggling to Get the...
My mum has a wee laptop that needs, when it boots up, to reverse-SSH connect itself to a server (so I can help out when needed).
I'm struggling to get the connection to persist when it is started by systemd.
In /reverse_SSH.sh I've got something like this:
#!/bin/bash
while true; do
ssh -R 19123:localhost:22 mum@
sleep 1000
done
In /etc/systemd/system/reverse_SSH.service I've got something like this:
[Unit]
Description=reverse-SSH
[Service]
Type=fork
ExecStart=/reverse_SSH.sh
[Install]
WantedBy=multi-user.target
When I run sudo systemctl start reverse_SSH, the SSH connection does appear to happen, and the MOTD of the server can be seen in the output of sudo systemctl status reverse_SSH, but the SSH connection doesn't seem to persist and I can't access the machine on the server with a command like ssh sonnyboy@localhost -p 19123.
What nonsense am I doing wrong? Thanks!
1 Answer
I would prefer to use the autossh package for such service. So first install it:
sudo apt update && sudo apt install autossh
Then create configuration entry for your connection, by creating a new file within the directory /etc/ssh/ssh_config.d/. Let's call it reverse.ssh.. Here is an example:
sudo nano /etc/ssh/ssh_config.d/reverse.ssh.
# This file is loaded by /etc/ssh/ssh_config
Host reverse.ssh.
HostName
IdentityFile /root/.ssh/your_passles_id_rsa
User mum
Port 22
RemoteForward 19123 127.0.0.1:22
GatewayPorts yes
Compression yes
- Note the SSH key is possession of the root user who will manage the connection by our service.
- The last two options are not mandatory.
Finally create the service:
sudo nano /etc/systemd/system/reverse-autossh-www-example-org.service
[Unit]
Description=Keeps a resident tunnel to open
#After=network.target
After=network-online.target
[Service]
User=root
ExecStart=/usr/bin/autossh -M 0 -N -q -o "ServerAliveInterval 60" -o "ServerAliveCountMax 3" reverse.ssh.
ExecStop=/usr/bin/killall -s KILL autossh
#ExecStop=/bin/kill $MAINPID
Restart=always
RestartSec=3
#Environment=AUTOSSH_GATETIME=0
[Install]
WantedBy=multi-user.target
Enable and start the service:
sudo systemctl daemon-reload
sudo systemctl enable reverse-autossh-www-example-org.service
sudo systemctl start reverse-autossh-www-example-org.service
I've used this configuration for last two years in order to solve similar task - it works like a charm. However, here are few references:
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