Setup SSH for accessing outside from network

To set up port forwarding for SSH from a router to allow external access to a Kali Linux machine, you need to configure your router and ensure your Kali Linux SSH server is correctly set up. Here's a step-by-step guide on how to do this:

### Step 1: Configure SSH on Kali Linux
1. **Install OpenSSH Server** (if not already installed):
   ```bash
   sudo apt update
   sudo apt install openssh-server
   ```

2. **Start and Enable SSH Service**:
   ```bash
   sudo systemctl start ssh
   sudo systemctl enable ssh
   ```

3. **Check SSH Status**:
   ```bash
   sudo systemctl status ssh
   ```

4. **Optional: Change Default SSH Port** (for security):
   Edit the SSH configuration file:
   ```bash
   sudo nano /etc/ssh/sshd_config
   ```
   Change the line:
   ```
   #Port 22
   ```
   to something like:
   ```
   Port 8022
   ```
   Save the file and restart the SSH service:
   ```bash
   sudo systemctl restart ssh
   ```

### Step 2: Configure Port Forwarding on the Router
Since router interfaces vary by manufacturer, the general steps are as follows:

1. **Access the Router's Web Interface**:
   - Open a web browser and enter the router's IP address (commonly 192.168.1.1 or 192.168.0.1).
   - Log in with the router's admin credentials.

2. **Locate the Port Forwarding Section**:
   - This is often found under "Advanced Settings," "Firewall," or "NAT/QoS."

3. **Create a Port Forwarding Rule**:
   - **Service Name**: Give the rule a name (e.g., "SSH to Kali").
   - **Port Range**: Enter the external port you want to use (e.g., 8022).
   - **Internal IP Address**: Enter the local IP address of your Kali Linux machine (find it using `ifconfig` or `ip a`).
   - **Internal Port**: Enter the SSH port on your Kali Linux machine (default 22, or 8022 if you changed it).
   - **Protocol**: Set to TCP.
   - **Save/Apply** the settings.

### Step 3: Ensure Firewall on Kali Linux is Allowing SSH Traffic
1. **Allow SSH Traffic**:
   ```bash
   sudo ufw allow 22/tcp    # or the custom port number if you changed it
   sudo ufw enable
   sudo ufw status
   ```

### Step 4: Test External SSH Access
1. **Find Your External IP Address**:
   - You can find it by searching "What is my IP" on Google.

2. **Test the SSH Connection**:
   From an external network (not the same local network as your Kali Linux machine), use an SSH client to connect:
   ```bash
   ssh -p 8022 user@your-external-ip
   ```
   Replace `user` with your Kali Linux username, `8022` with your chosen external port, and `your-external-ip` with your external IP address.

### Summary
By following these steps, you will set up port forwarding on your router to allow external SSH access to your Kali Linux machine. Ensure your router settings are saved and your SSH service on Kali Linux is running properly. For added security, consider using a non-standard port and disabling password authentication in favor of SSH key-based authentication.