From 49278204a4a0c292083ef7daad8e1d0dfaa47806 Mon Sep 17 00:00:00 2001 From: Yuri Tatishchev Date: Sat, 29 Mar 2025 23:01:40 -0700 Subject: [PATCH] router: ifconfig: disable linux arp proxy behavior by default By default, Linux will respond to ARP requests that belong to other interfaces. Normally this isn't a problem, but it causes issues since my WAN and LAN20 are technically bridged. --- hosts/router/ifconfig.nix | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hosts/router/ifconfig.nix b/hosts/router/ifconfig.nix index 132b47e..63f3198 100644 --- a/hosts/router/ifconfig.nix +++ b/hosts/router/ifconfig.nix @@ -46,6 +46,12 @@ let }; in { + # By default, Linux will respond to ARP requests that belong to other interfaces. + # Normally this isn't a problem, but it causes issues + # since my WAN and LAN20 are technically bridged. + # https://networkengineering.stackexchange.com/questions/83071/why-linux-answers-arp-requests-for-ips-that-belong-to-different-network-interfac + boot.kernel.sysctl."net.ipv4.conf.default.arp_filter" = 1; + # It is impossible to do multiple prefix requests with networkd, # so I use dhcpcd for this # https://github.com/systemd/systemd/issues/22571