nftables: init config package

debian/changelog

@@ -1,6 +1,7 @@
 shione-config (0.1.0) UNRELEASED; urgency=low
 
   * Add current openssh-server configuration.
+  * Add current nftables configuration.
   * Initial release.
 
  -- Mohammed Amar-Bensaber <renken@shione.net>  Sun, 24 Aug 2024 16:06:00 +0200

debian/control

@@ -14,3 +14,12 @@ Provides: ${diverted-files}
 Conflicts: ${diverted-files}
 Description: Opinionated openssh-server configuration.
   Opinionated openssh-server configuration.
+
+Package: nftables-config
+Architecture: all
+Multi-Arch: foreign
+Depends: ${misc:Depends}, nftables
+Provides: ${diverted-files}
+Conflicts: ${diverted-files}
+Description: Shione nftables configuration.
+  Nftables configuration for shione.net.

debian/nftables-config.displace

@@ -0,0 +1 @@
+/etc/nftables.conf

debian/nftables-config.install

@@ -0,0 +1 @@
+files/etc/nftables.conf /etc/

files/etc/nftables.conf

@@ -0,0 +1,122 @@
+#!/usr/sbin/nft -f
+
+flush ruleset
+
+define eth_iface = enp1s0
+define wg_iface = wg0
+define wg_port = 51820
+define dns_port = 53
+define srt_input_udp_port = 60001
+define srt_output_port = 60000
+define srb2kart_port = 5029
+define syncthing_port = 22000
+define syncthing_gui_port = 8384
+
+table inet filter {
+  chain input_ipv4 {
+    # accepting ping (icmp-echo-request) for diagnostic purposes.
+    # However, it also lets probes discover this host is alive.
+    # This sample accepts them within a certain rate limit:
+      icmp type echo-request limit rate 5/second accept
+  }
+
+  chain input_ipv6 {
+    # accept neighbour discovery otherwise connectivity breaks
+    icmpv6 type { nd-neighbor-solicit, nd-router-advert, nd-neighbor-advert } accept
+
+    # accepting ping (icmpv6-echo-request) for diagnostic purposes.
+    # However, it also lets probes discover this host is alive.
+    # This sample accepts them within a certain rate limit:
+    icmpv6 type echo-request limit rate 5/second accept
+  }
+
+  chain input_world {
+    udp dport {
+      $wg_port
+    } accept
+  }
+
+  chain input_vpn {
+    # TODO: Should we limit source address space?
+    #
+    # ip saddr 10.8.0.0/32
+
+    # Allow VPN to use DNS.
+    tcp dport {
+      $dns_port
+      $syncthing_port,
+      $syncthing_gui_port,
+    } accept
+
+    udp dport {
+      $dns_port,
+      $srt_input_udp_port,
+      $syncthing_port,
+    } accept
+  }
+
+  chain input {
+    # By default, drop all traffic unless it meets a filter
+    # criteria specified by the rules that follow below.
+    type filter hook input priority 0; policy drop;
+
+    # Allow traffic from established and related packets, drop invalid
+    ct state vmap { established : accept, related : accept, invalid : drop }
+
+    # Jump to chain according to layer 3 protocol using a verdict map
+    meta protocol vmap { ip : jump input_ipv4, ip6 : jump input_ipv6 }
+
+    # Allow traffic for/from both the world and VPN.
+    tcp dport {
+      ssh,
+      http,
+      https,
+    } accept
+
+    udp dport {
+      $srt_output_port,
+      $srb2kart_port,
+    } accept
+
+    # allow loopback traffic, anything else jump to chain for further evaluation
+    iifname vmap { lo : accept, $eth_iface : jump input_world, $wg_iface : jump input_vpn }
+
+    # Uncomment to enable logging of denied input traffic
+    # log prefix "[nftables] input Denied: " counter drop
+
+    # Reject with polite "port unreachable" icmp response
+    reject
+  }
+
+  chain forward {
+    # Drop everything (assumes this device is not a router)
+    # type filter hook forward priority filter;
+    type filter hook forward priority 0; policy drop;
+
+    # Forward all icmp/icmpv6 packets
+    meta l4proto { icmp, ipv6-icmp } accept
+
+    # Allow traffic from established and related packets, drop invalid
+    ct state vmap { established : accept, related : accept, invalid : drop }
+
+    # Forward traffic within the VPN and between it and the outside world.
+    iifname $wg_iface oifname $wg_iface counter accept;
+    iifname $wg_iface oifname $eth_iface counter accept;
+    iifname $eth_iface oifname $eth_iface counter accept;
+
+    # Reject with polite "host unreachable" icmp response
+    reject with icmpx type host-unreachable
+  }
+
+  chain prerouting {
+    type nat hook prerouting priority 0;
+  }
+
+  chain postrouting {
+    type nat hook postrouting priority 100; policy accept;
+    # Masquerade all packets from WireGuard VPN to the outside world.
+    iifname $wg_iface oifname $eth_iface masquerade
+  }
+
+  # no need to define output chain, default policy is accept if undefined.
+}