IPv6 is enabled by default. Stateless address autoconfiguration is used to automatically assign IPv6 addresses to all interfaces. You can disable IPv6 support globally by setting: networking.enableIPv6 = false; You can disable IPv6 on a single interface using a normal sysctl (in this example, we use interface eth0): boot.kernel.sysctl."net.ipv6.conf.eth0.disable_ipv6" = true;