Open Source Linux Client for Check Point VPN Tunnels

This project contains the source code for an unofficial Linux client for Check Point VPN, written in Rust.

Advantages Over the Official SNX Client for Linux

• Open source
• IPSec support (provides a much faster tunnel)
• More authentication methods
• Better privacy for DNS requests: only requests for VPN-specific suffixes are routed through the tunnel
• Better integration with system DNS resolver
• Optional integration with GNOME Keyring or KDE KWallet
• Customizable routing and DNS settings

Implemented Features

• SAML SSO authentication (only with IPSec tunnel)
• Username/password authentication with MFA support
• Certificate authentication via provided client certificate (PFX, PEM, or HW token)
• HW token support via PKCS11 (only with IPSec tunnel)
• GTK frontend with tray icon
• SSL tunnel via Linux TUN device
• IPSec tunnel via Linux native kernel XFRM interface
• Store passwords in the keychain using Secret Service API
• Automatic IPSec tunnel reconnection without authentication (via optional parameter)

Limitations

• Certificate enrollment and renewal is not supported

Roadmap

• Packaging

System Requirements

• A recent Linux distribution with kernel version 4.19 or higher
• systemd-resolved recommended as a global DNS resolver
• iproute2 (the ip command)
• D-Bus
• GTK3 and libappindicator3 for the GUI frontend

DNS resolver configuration

By default, if systemd-resolved is not detected as a global DNS resolver, snx-rs will fall back to modify the /etc/resolv.conf file directly and DNS servers acquired from the tunnel will be used globally. For better privacy, use the split-tunneling provided by systemd-resolved.

In order to find out whether it is already enabled, check the /etc/resolv.conf file:

readlink /etc/resolv.conf

If it is a symlink pointing to /run/systemd/resolve/stub-resolv.conf then it is already configured on your system. Otherwise follow these steps:

1. sudo ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf
2. sudo systemctl enable --now systemd-resolved
3. sudo systemctl restart NetworkManager

Differences between SSL and IPSec tunnels

IPSec is recommended for all connections because of the performance and feature set. However, in certain situations, it might not work (for example because of the corporate firewall policies). In this case the SSL tunnel can be used which is a subject to some limitations.

Note: IPSec requires that IPv6 module is enabled in the kernel.

	SSL	IPSec
Implementation	User-space TCP-encapsulated tunnel via TUN device	Kernel-space UDP-encapsulated tunnel via native OS support
Performance	Up to 2MB/s	Close to plain connection, limited by VPN server capacity
Ports	TCP port 443	UDP ports 4500 and 500
Supported authentication types	Username/password + MFA codes Certificate	Username/password + MFA codes Certificate + MFA codes Certificate from hardware token + MFA codes SAML SSO with browser-based authentication

GUI Usage

• Run the main application in command mode: sudo snx-rs -m command or install it as a systemd service
• Run the snx-rs-gui application, which will display a tray icon with a menu
• GNOME environment: if the tray icon is not displayed, install the Appindicator extension

Command Line Usage

Check the Configuration Options section for a list of all available options. Options can be specified in the configuration file and the path of the file given via -c /path/to/custom.conf command line parameter.

Alternatively, in standalone mode, they can be specified via the command line of the snx-rs executable.

Before the client can establish a connection, it must know the login (authentication) method to use (--login-type or -o option). To find the supported login types, run it with the -m info parameter:

snx-rs -m info -s remote.acme.com

This command will display the supported login types. Use the vpn_XXX identifier as the login type. If a certificate error is returned, try adding the -X true command line parameter to ignore certificate errors.

Example output (may differ for your server):

Supported tunnel protocols:
        IPSec
        SSL
        L2TP
Available login types:
        vpn_Microsoft_Authenticator (Microsoft Authenticator)
        vpn_Emergency_Access (Emergency Access)
        vpn_Username_Password (Username Password)
        vpn_Azure_Authentication (Azure Authentication)
        vpn (Standard)

There are two ways to use the application:

• Command Mode: Selected by the -m command parameter. In this mode, the application runs as a service without establishing a connection and awaits commands from the external client. Use the snxctl utility to send commands to the service. This mode is recommended for desktop usage. The following commands are accepted:
  • connect: Establish a connection. Parameters are taken from the ~/.config/snx-rs/snx-rs.conf file.
  • disconnect: Disconnect a tunnel.
  • reconnect: Drop the connection and then reconnect.
  • status: Show connection status.
  • info: Show server authentication methods and supported tunnel types.
  • Run it with the --help option to get usage help.
• Standalone Service Mode: Selected by the -m standalone parameter. This is the default mode if no parameters are specified. Run snx-rs --help to get help with all command line parameters. In this mode, the application takes connection parameters either from the command line or from the specified configuration file. This mode is recommended for headless usage.

Certificate validation

The following parameters control certificate validation during TLS and IKE exchanges:

• ca-cert: Comma-separated list of paths to PEM or DER files which contain custom CA root certificates
• no-cert-check: true|false. Disable server hostname check for TLS connection. Insecure and not recommended. Default is false.
• ignore-server-cert: true|false. Disable all TLS certificate checks. Insecure and not recommended. Default is false.
• ipsec-cert-check: true|false. Enable additional certificate checks for IKE exchange. Requires custom CA root certificate to be specified. Standard system-wide CA roots are not used. Default is false (certificates are not checked).

Note that enabling any of the insecure options may compromise the channel security.

Certificate Authentication

The following parameters control certificate-based authentication:

• cert-type: One of "none", "pkcs12", "pkcs8", or "pkcs11". Choose "pkcs12" to read the certificate from an external PFX file. Choose "pkcs8" to read the certificate from an external PEM file (containing both private key and x509 cert). Choose "pkcs11" to use a hardware token via a PKCS11 driver.
• cert-path: Path to the PFX, PEM, or custom PKCS11 driver file, depending on the selected cert type. The default PKCS11 driver is opensc-pkcs11.so, which requires the opensc package to be installed.
• cert-password: Password for PKCS12 or PIN for PKCS11. Must be provided for those types.
• cert-id: Optional hexadecimal ID of the certificate for the PKCS11 type. Could be in the form of 'xx:xx:xx' or 'xxxxxx'.

Persistent IPSec session (experimental)

A new ike-persist option will save IPSec session to disk and restore it after the service or computer restarts, it will then attempt to automatically reconnect the tunnel without authentication. This parameter works best in combination with the ike-lifetime option: for example, setting ike-lifetime to 604800 will keep the session for 7 days.

Note that most IPSec servers have shorter IKE duration configured, so it may be terminated earlier. There is also a corresponding GUI switch under "Misc settings" category in the settings dialog.

Automatic channel reconnection will happen when running in the standalone mode, when GUI application starts or when snxctl sends the "connect" command.

Additional Usage Notes

• If SAML SSO authentication is used in standalone mode, the browser URL will be printed to the console. In command mode, the browser will be opened automatically.
• If the password is not provided in the configuration file, the first entered MFA challenge code will be stored in the OS keychain unless the no-keychain parameter is specified. Keychain integration is provided only in command mode.

Troubleshooting common problems

Problem	Solution
deadline has elapsed	Check if the correct login type is specified (one of the vpn_XXX identifiers returned from the "-m info" command).
failed to fill whole buffer	This error means the IPSec traffic is intercepted by man-in-the-middle, which could be a router doing packet inspection or an attacker.
Unknown device type	Make sure IPv6 protocol is enabled in the Linux kernel and 'xfrm' module can be loaded with sudo modprobe xfrm. IPSec support requires IPv6 to be enabled.
[0020] The user is not defined properly	Application failed to negotiate IPSec encryption parameters. Usually it means that Check Point server is misconfigured with the obsolete insecure ciphers.
error sending request for url (https://IP_OR_HOSTNAME/clients/)	VPN server certificate is self-signed or untrusted. Use ignore-server-cert parameter to disable all HTTPS certificate checks. Use no-cert-check to only disable hostname validation.

Contributing

Pull requests, bug reports, and suggestions are welcome. This is a hobby project I maintain in my free time.

Before opening a PR, make sure to reformat the sources with the cargo fmt command and run it through the cargo clippy for any warnings.

Building from Sources

The easiest way to build the project is using the distrobox:

• Provision distrobox container: distrobox create --image ubuntu:22.04 --name snx-ubuntu
• Enter the container: distrobox enter snx-ubuntu
• Install the required dependencies: sudo apt install build-essential pkg-config libssl-dev libgtk-3-dev
• Install a recent Rust compiler
• Run cargo build to build the debug version, or cargo build --release to build the release version
• If the GUI frontend is not needed, build it with cargo build --release --workspace --exclude snx-rs-gui

Acknowledgements

Special thanks to the cpyvpn project for inspiration around SAML and IKEv1 exchange.

License

Licensed under the GNU Affero General Public License version 3. c