đ ī¸ Day 8: Linux Services
Services are the silent workers of your operating system. đˇââī¸
đ Service vs. Process
A Service is essentially a process that runs in the background, often starting automatically at boot.
| Feature | Service đ ī¸ | Process đ |
|---|---|---|
| Start | Automatic or Manual | Manual (User) |
| Mode | Background (Daemon) | Foreground (mostly) |
| Lifespan | Long-running | Often short-lived |
| Example | ssh, apache2 |
ls, cd, cat |
Note: In Kali,
systemdis the manager that controls these services.
đšī¸ Essential Service Commands
Manage your services using systemctl.
1. Check Status
systemctl status ssh
Look for Active: active (running) to confirm it's working.
2. Start a Service
sudo systemctl start ssh
Starts the service immediately.
3. Stop a Service
sudo systemctl stop ssh
Stops the service immediately.
4. Enable at Boot
sudo systemctl enable ssh
Ensures the service starts automatically when you turn on the computer.
5. Disable at Boot
sudo systemctl disable ssh
Prevents the service from starting automatically.
6. Restart
sudo systemctl restart ssh
Stops and then starts the service (useful for applying config changes).
7. List Running Services
systemctl --type=service --state=running
â ī¸ Why Services Matter?
Understanding services is critical for security:
- Target: Hackers often target services rather than simple processes.
- Persistence: Malware often installs itself as a service to run continuously in the background using misleading names to hide.
- Privilege: If a vulnerable service runs as
root, compromising it gives the attacker full control. đģ