LWM-Linux/04 - Networking in Linux/VPN and Proxy Configuration.md

i# VPN and proxy configuration in Linux

## 1. VPN Configuration

VPNs (Virtual Private Networks) provide secure, encrypted connections over public networks. There are several VPN protocols and clients available for Linux.

### OpenVPN:
OpenVPN is one of the most popular and secure VPN protocols. To set it up:

- 1. Install OpenVPN:
```
sudo apt install openvpn
```

- 2. Obtain configuration files from your VPN provider.

- 3. Connect to the VPN:
```
sudo openvpn --config /path/to/your/config.ovpn
```

- 4. For automatic connection, create a systemd service:
```
sudo nano /etc/systemd/system/openvpn.service
```
Add the following content:
```
[Unit]
Description=OpenVPN connection to YOUR_VPN
After=network.target

[Service]
ExecStart=/usr/sbin/openvpn --config /path/to/your/config.ovpn
Restart=always

[Install]
WantedBy=multi-user.target
```

Enable and start the service:
```
sudo systemctl enable openvpn.service
sudo systemctl start openvpn.service
```

### WireGuard:
WireGuard is a newer, faster VPN protocol. To set it up:

- a. Install WireGuard:
```
sudo apt install wireguard
```

- b. Create a configuration file:
```
sudo nano /etc/wireguard/wg0.conf
```
Add your WireGuard configuration details.

- c. Start the WireGuard connection:
```
sudo wg-quick up wg0
```

- d. To enable automatic connection on boot:
```
sudo systemctl enable wg-quick@wg0
```

### Built-in VPN clients:
Many Linux distributions include built-in VPN clients in their network managers, supporting protocols like OpenVPN, L2TP/IPsec, and PPTP.

## 2. Proxy Configuration

Proxies route your traffic through an intermediary server. There are several ways to configure proxies in Linux:

### Environment variables:
Set these variables in your shell configuration file (e.g., ~/.bashrc):
```
export http_proxy="http://proxy_server:port"
export https_proxy="http://proxy_server:port"
export ftp_proxy="http://proxy_server:port"
export no_proxy="localhost,127.0.0.1,::1"
```

### System-wide proxy settings:
For GNOME-based systems:
- a. Open Settings > Network > Network Proxy
- b. Choose "Manual" and enter your proxy details

### For KDE-based systems:
- a. Open System Settings > Network Settings > Proxy
- b. Choose "Manual" and enter your proxy details

### Application-specific proxy settings:
Many applications have their own proxy settings. For example:

- Firefox: Preferences > Network Settings > Configure Proxy Access to the Internet
- Chrome: Settings > Advanced > System > Open your computer's proxy settings

### Command-line tools:
Use proxychains to route terminal commands through a proxy:

#### 1. Install proxychains:
```
sudo apt install proxychains
```

#### 2. Configure proxychains:
```
sudo nano /etc/proxychains.conf
```
Add your proxy server details.

#### 3. Use proxychains:
```
proxychains command_to_run
```

### SOCKS proxy with SSH:
Create a SOCKS proxy using SSH:
```
ssh -D 1080 -f -C -q -N username@remote_host
```
Then configure applications to use SOCKS5 proxy at 127.0.0.1:1080.

## 3. Testing and Verification

To verify your VPN or proxy configuration:

- Check your IP address:
```
curl ifconfig.me
```

- DNS leak test:
```
dig +short myip.opendns.com @resolver1.opendns.com
```

- WebRTC leak test (in browsers)

- Use tools like ipleak.net or dnsleak.com

## 4. Security Considerations

- Keep your VPN client and system updated
- Use strong authentication methods (e.g., certificates for OpenVPN)
- Be cautious with free VPN or proxy services
- Consider using a kill switch to prevent traffic leaks if the VPN disconnects

## 5. Troubleshooting

- Check logs: `journalctl -u openvpn` or `journalctl -u wg-quick@wg0`
- Verify DNS settings
- Ensure correct permissions on configuration files
- Check for conflicting network settings

- [(1) Setting Up a VPN on Linux Mint: A Step-by-Step Guide - FOSS Linux.](https://www.fosslinux.com/102356/how-to-set-up-a-vpn-on-linux-mint.htm.)
- [(2) How to Configure OpenVPN in Linux Mint? – IPVanish.](https://support.ipvanish.com/hc/en-us/articles/360001738513-How-to-Configure-OpenVPN-in-Linux-Mint.)
- [(3) How to configure OpenVPN on Linux Mint - FastVPN - Namecheap.](https://www.namecheap.com/support/knowledgebase/article.aspx/10416/2271/how-to-configure-openvpn-on-linux-mint/.)
- [(4) How to Set up an OpenVPN Connection in Linux Mint - Comparitech.](https://www.comparitech.com/blog/vpn-privacy/openvpn-connection-linux-mint/.)