Closer...

eth0.network

@@ -5,6 +5,4 @@ Name=eth0
 [Network]
 DHCP=yes
 Gateway=0.0.0.0/1
-DNS=8.8.8.8
-DNS=8.8.4.4
 IPForward=yes

lan0.network

@@ -1,8 +1,8 @@
 [Match]
 Name=lan0
-# MACAddress=dc:a6:32:0a:b5:84
+# MACAddress=00:e0:4c:6d:0c:74
 
 [Network]
 Address=10.0.0.1/24
 IPForward=yes
-IPMasquerade=yes
+IPMasquerade=ipv4

link.fish

@@ -0,0 +1,12 @@
+#!/usr/bin/env fish
+
+function rmlink
+	rm -f $argv[1]
+	ezln $argv[1] $argv[2]
+end
+
+rmlink dnsmasq.conf /etc/dnsmasq.conf
+rmlink usb-ethernet-as-lan0.link /etc/systemd/network/10-usb-eth-adapter.link
+
+cp eth0.network /etc/systemd/network/eth0.network
+cp lan0.network /etc/systemd/network/lan0.network

nftables

@@ -3,6 +3,8 @@ flush ruleset
 table inet filter {
 	chain input {
 		type filter hook input priority filter; policy accept;
+		udp dport 546 accept
+		udp dport 53 accept
 		ct state { established, related } accept
 		ct state invalid drop
 		iifname "lo" accept

readme.md

@@ -1,9 +1,3 @@
-+ Guide: https://wiki.archlinux.org/title/router
-+ Interfaces configuration:
-	+ See `/etc/systemd/network`
-+ DNS & LAN DHCP
-	+ See `/etc/dnsmasq.conf`
-	+ See `/etc/sysctl.d/30-ipforward.conf`
-+ Firewall & NAT
-	+ See `sudo iptables --list`
-	+ See `cat /etc/iptables/iptables.rules`
+# TODO
+
++ IPv6?