In this article:
    Applicable to:
    • Twingate Component: Client
    • Platform: Linux (NixOS)

    Overview

    The Twingate Client does not detect a firewall if networking.firewall is used to configure firewall rules, on NixOS.

    Cause

    While the NixOS provided firewall solution uses iptables in the backend (a firewall solution supported by the Twingate Client), the Twingate Client is unable to detect NixOS’s iptables use of inetworking.firewall.

    Solution

    To use iptables for the Twingate Client device posture firewall, the firewall requirements must be met.

    Firewall Requirements

    ⚠️ Warning
    • Before applying any changes to firewall rules, review your organization's security policies and test in a controlled environment.
    • Changing firewall policies may block legitimate traffic, including SSH and DNS. Always ensure that essential traffic is explicitly allowed before setting restrictive policies.
    • networking.firewall must be disabled.
    • iptables must be installed.
    • INPUT chain's default policy must be set to DROP.
    • For details on setting default policies in iptables, see either: