Ubuntu(systemd) tmate service for ssh

tmate_for_ssh.md

The motivation is: reverse ssh to remote computer, the only thing needed is that the remote is connected to the Internet.

1. On 18.04 or older remote, get tmate, put it in /usr/local/bin (20.04 is 2.4.0 but has issues /w -F [tmate-io/tmate#204]):

curl -L https://github.com/tmate-io/tmate/releases/download/2.4.0/tmate-2.4.0-static-linux-amd64.tar.xz|tar xJv
sudo mv tmate-2.4.0-static-linux-amd/tmate /usr/local/bin

2. Put public keys in ~/.ssh/authorized_keys

3. Get API key from https://tmate.io/ (or host your own server)

4. Create ~/.tmate.conf

set tmate-api-key "<YOUR_API_KEY>"                                
set tmate-session-name "<SESSION_NAME>"                     
set tmate-authorized-keys "~/.ssh/authorized_keys"        

Session name is chosen by you

5. Create /etc/systemd/system/tmate@.service

[Install]
WantedBy=multi-user.target

[Unit]
Description=Tmate-SSH
Wants=network-online.target
After=network-online.target

[Service]
Type=simple
Restart=always
User=%i
ExecStart=/usr/local/bin/tmate -F

6. Install tmate as service with

systemctl daemon-reload
systemctl start tmate@<user>
systemctl enable tmate@<user>

7. You can reboot and ssh from any computer with private key:

ssh <REGISTRED_USERNAME_FROM_TMATE>/<SESSION_NAME>@lon1.tmate.io