From 29ddd0cb7c2c37d8aaea51e0eecb70d8c5e88208 Mon Sep 17 00:00:00 2001 From: Erik Simon Date: Wed, 29 Jul 2026 21:43:11 +0200 Subject: [PATCH] neptun: stop processing router advertisements on eth0 Addressing is fully static, but netcup's router still sends periodic RAs on this segment; the kernel then tries (and fails, since the static route already exists) to install its own default route from them, spamming "ndisc_router_discovery failed to add default route" on the console. --- hosts/neptun/configuration.nix | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hosts/neptun/configuration.nix b/hosts/neptun/configuration.nix index 8ac3d1a..ec06d6b 100644 --- a/hosts/neptun/configuration.nix +++ b/hosts/neptun/configuration.nix @@ -42,6 +42,12 @@ # default via fe80::1 dev eth0 metric 1024 onlink networking.defaultGateway6 = { address = "fe80::1"; interface = "eth0"; }; networking.nameservers = [ "9.9.9.9" "1.1.1.1" "2620:fe::fe" ]; + # Addressing is fully static above, but netcup's router still sends periodic + # RAs on this segment; the kernel then tries (and fails, since the static + # route already exists) to install its own default route from them, spamming + # "ndisc_router_discovery failed to add default route" on the console. Stop + # it from processing RAs on eth0 at all rather than just live with the noise. + boot.kernel.sysctl."net.ipv6.conf.eth0.accept_ra" = 0; # ---- Local split-DNS stub ---- # neptun must NOT take the tailnet's DNS: headscale points every node at