vpn

openvpn

vpn tools are essential for creating secure and private connections over the Internet. They enable users to access restricted content, enhance privacy, and secure sensitive data transmission. By encrypting traffic, VPNs protect users from eavesdropping and other potential threats.

OpenVPN

An open-source VPN solution that provides a secure point-to-point or site-to-site connection in routed or bridged configurations.

Options:

  • -c [config file]: Specify the configuration file to use.
  • -r [remote server]: Specify the remote server to connect to.
  • -p [port number]: Specify the port number to connect to the server.
  • --proto [protocol]: Define the protocol to use (e.g., tcp, udp).
  • -d [device]: Specify the network device type, such as tun or tap.
  • --auth-user-pass [file]: Provide a file with username and password for authentication.
  • --cipher [cipher]: Choose the encryption cipher (e.g., AES-256-CBC).
  • --ca [ca file]: Specify the Certificate Authority (CA) file.
  • --cert [certificate file]: Provide the client certificate file.
  • --key [key file]: Provide the private key file for the client.
  • --route [network] [netmask]: Add a static route.
  • -v: Enable verbose output for detailed information.

Installation:

> sudo apt update && sudo apt install openvpn

Start and Verify:

  • Start: sudo openvpn --config /path/to/config.ovpn
  • Verify: openvpn --version

Example to Connect to a VPN:

> sudo openvpn --config /path/to/config.ovpn

WireGuard

A modern VPN protocol that aims for simplicity and high performance. WireGuard is designed to be easy to configure and deploy.

Options:

  • wg-quick up [config file]: Bring up the WireGuard interface with the specified configuration file.
  • wg-quick down [config file]: Bring down the WireGuard interface.
  • wg genkey: Generate a new private key.wg pubkey: Generate a public key from a given private key.
  • wg set [interface]: Configure the WireGuard interface with specific settings.
  • wg setconf [interface] [config file]: Load configuration settings from a file.
  • wg show [interface]: Display the current configuration and status of the interface.
  • wg addconf [interface] [config file]: Append configuration to the current interface.
  • wg syncconf [interface] [config file]: Sync the interface with the provided configuration file.

Installation:

> sudo apt update && sudo apt install wireguard

Start and Verify:

  • Start: sudo wg-quick up /path/to/wg0.conf
  • Verify: sudo wg

Example to Connect to a VPN:

> sudo wg-quick up /path/to/wg0.conf

StrongSwan

An open-source implementation of IPsec for Linux and other Unix-like operating systems, StrongSwan is designed to secure IP traffic.

Options:

  • --load-all: Load all available connections and credentials.
  • --load-conn [conn name]: Load a specific connection configuration.
  • --load-creds: Load all credentials for authentication.
  • --list-conns: List all defined connections.
  • --list-sas: List active security associations (SAs).
  • --list-certs: List all available certificates.
  • --list-pools: List all configured IP pools.
  • --terminate [conn name]: Terminate a specific connection.
  • --stats: Display statistics on IPsec performance.
  • --log [log file]: Specify the log file for output.

Installation:

> sudo apt update && sudo apt install strongswan

Start and Verify:

  • Start: sudo systemctl start strongswan
  • Verify: sudo systemctl status strongswan

Example to Connect to a VPN:

> sudo strongswan start

IPsec

A suite of protocols used to secure Internet Protocol (IP) communications through authenticating and encrypting each IP packet.

Options:

  • up [connection_name]: Establish a connection with the specified name.
  • down [connection_name]: Terminate a specific connection.
  • status: Display the current IPsec status, including active connections.
  • whack --name [conn name]: Specify the name of a connection for use with other commands.
  • whack --initiate: Initiate a connection manually.
  • whack --terminate: Terminate a manually initiated connection.
  • whack --list: List all known connections and their states.
  • whack --trafficstatus: Display traffic status information.
  • whack --listen: Start IPsec in listening mode for incoming connections.
  • whack --shutdown: Stop all IPsec services and connections.

Installation:

> sudo apt update && sudo apt install ipsec

Start and Verify:

  • Start: sudo ipsec start
  • Verify: sudo ipsec status

Example to Connect to a VPN:

> sudo ipsec up [connection_name]

SSTP

(Secure Socket Tunneling Protocol)

A form of VPN that encapsulates PPP traffic through an SSL channel, allowing for secure remote access.

Options:

  • --serverurl [url]: Specify the server URL to connect to.
  • -u [username]: Specify the username for authentication.
  • -p [password]: Specify the password for authentication.
  • --cert-warn: Allow the use of a certificate with a warning.
  • --ca-cert [path]: Specify the path to the Certificate Authority (CA) certificate for SSL verification.
  • --ipparam [param]: Define the IP parameters to use.
  • --log-stderr [path]: Log to standard error output to a specified file.
  • --log-level [level]: Set the log level for detailed logs.
  • --background: Run the client in the background after establishing the connection.
  • --debug: Enable debugging mode for more detailed output.
  • --help: Display the help information and available options.

Installation:

> sudo apt update && sudo apt install sstp-client

Start and Verify:

  • Start: sudo sstpc --log-level 4 --user [username] --password [password] sstp://[server]:[port]
  • Verify: Check logs for connection status.

Example to Connect to a VPN:

> sudo sstpc --log-level 4 --user [username] --password [password] sstp://[server]:[port]

OpenConnect

An open-source client for Cisco’s AnyConnect VPN that supports a variety of VPN configurations.

Options:

  • --serverurl [url]: Specify the server URL to connect to.
  • -u [username]: Specify the username for authentication.
  • --passwd-on-stdin: Read the password from standard input.
  • --servercert [cert]: Validate the server certificate.
  • -g [group]: Specify the authentication group.
  • --cookie [cookie]: Provide a cookie for authentication.
  • --background: Run the client in the background after the connection is established.
  • --script [script]: Specify a script to run after connecting.
  • --pid-file [file]: Specify the path for the process ID (PID) file.
  • --protocol [protocol]: Specify the VPN protocol to use.
  • --help: Display help information and available options

Installation:

> sudo apt update && sudo apt install openconnect

Start and Verify:

  • Start: sudo openconnect [vpn.server.com] --auth-group [group]
  • Verify: openconnect --version

Example to Connect to a VPN:

> sudo openconnect [vpn.server.com] --auth-group [group]

L2TP

(Layer 2 Tunneling Protocol)

L2TP (Layer 2 Tunneling Protocol) is a tunneling protocol used to support VPNs. However, L2TP itself does not provide encryption or confidentiality. It requires additional encryption (commonly through IPsec) to secure the connection.

Options:

  • -c [config]: Specify the configuration file to use.
  • -D: Enable debug output.
  • -p [pid]: Specify the process ID (PID) file.
  • -e: Display error messages.
  • -f: Run the process in the foreground.
  • -s: Log to syslog.
  • -v: Enable verbose output.
  • -h: Display help information.
  • -n: Disable running as a daemon.
  • -l [log]: Specify the path for the log file.

Installation:

> sudo apt update && sudo apt install xl2tpd

Start and Verify:

  • Start: sudo systemctl start xl2tpd
  • Verify: sudo systemctl status xl2tpd

Example to Connect to a VPN:

To connect to a VPN using L2TP with IPsec, you would typically use the ipsec command. L2TP generally relies on IPsec for security, so ensure your system has IPsec configured.

> sudo ipsec up [connection_name]

SoftEther VPN

SoftEther is an open-source, multi-protocol VPN software that provides an easy-to-use and flexible VPN solution. It supports various VPN protocols such as L2TP, SSTP, OpenVPN, and more, allowing for secure and reliable VPN connections.

Options:

  • /SERVER: Specify the VPN server to connect to.
  • /PORT [port]: Specify the port for the VPN server.
  • /HUB [hub]: Define the VPN hub to use.
  • /CMD [command]: Specify the command to execute.
  • /PASSWORD [password]: Provide the password for authentication.
  • /user [username]: Provide the username for authentication.
  • /IN [input]: Specify the input parameter.
  • /OUT [output]: Specify the output parameter.
  • /ENCRYPTION [encryption]: Specify the encryption type to use.
  • /LANG [language]: Specify the language for the client interface.

Installation:

> sudo apt update && sudo apt install softether-vpnclient

Start and Verify:

  • Start: sudo vpncmd
  • Verify: vpncmd <server> /client /status

Example to Connect to a VPN:

> sudo vpncmd <server> /client /connect

Additional Options

Each VPN tool may have further options, such as:

  • Configuration Files: Set up custom configurations for each tool.
  • Logging Levels: Adjust verbosity for debugging and tracking activity.
  • Authentication Details: Specify credentials for VPNs that require login.