systemd listen on port and run command on connect

systemctl start restart-db.service


● restart-db.service – Restart MySQL Listener
Loaded: loaded (/lib/systemd/system/restart-db.service; disabled; vendor preset: enabled)
Active: active (running) since Mon 2023-11-27 21:29:28 UTC; 11s ago
Main PID: 41246 (bash)
Tasks: 2 (limit: 76710)
Memory: 572.0K
CPU: 1ms
CGroup: /system.slice/restart-db.service
├─41246 /bin/bash -xc “echo -e \”HTTP/1.1 204 No Content\\r\\nConnection: close\\r\\n\\r\” | nc -p 7777 -l -w 1; sudo systemctl restart mysql”
└─41248 nc -p 7777 -l -w

vim /etc/sudoers.d/restart-db
restart ALL=(ALL) NOPASSWD: /usr/bin/systemctl restart mysql

Also possible use socat with some simple auth:
socat -u TCP-LISTEN:7777,keepalive,reuseaddr,rcvbuf=7777 STDOUT | grep -w -q “mypassword” && sudo systemctl restart mysql

netstat -natp| grep :111
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 1/systemd

To 111 port listening disable you can like this:
systemctl stop rpcbind.socket

systemctl disable rpcbind.socket
Removed symlink /etc/systemd/system/sockets.target.wants/rpcbind.socket

chmod +x /etc/rc.d/rc.local
systemctl enable rc-local

systemctl start rc-local or jus try reboot server

journalctl –vacuum-time=2d

journalctl –vacuum-size=500M


systemctl isolate runlevel3.target


systemctl isolate runlevel5.target


systemctl list-unit-files –type=service

You can fix this with some extra service and systemd:

[Unit]
After=network.target

[Service]
RemainAfterExit=yes
ExecStart=-/bin/true
ExecStop=-/usr/bin/pkill sshfs

[Install]
WantedBy=multi-user.target

place this to /etc/systemd/system/