ansible-infra/resources/chaosknoten/router/nftables/nftables.conf
June e3c12b18e8
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router(host): add nftables config for basic router functionality
2025-09-20 23:34:17 +02:00

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#!/usr/sbin/nft -f
## Variables
# Interfaces
define if_net1_v4_wan = "net1"
define if_net2_v6_wan = "net2"
define if_net0_2_v4_nat = "net0.2"
define if_net0_3_ci_runner = "net0.3"
# Interface Groups
define wan_ifs = { $if_net1_v4_wan,
$if_net2_v6_wan }
define lan_ifs = { $if_net0_2_v4_nat,
$if_net0_3_ci_runner }
## Rules
table inet reverse-path-forwarding {
chain rpf-filter {
type filter hook prerouting priority mangle + 10; policy drop;
# Only allow packets if their source address is routed via their incoming interface.
# https://github.com/NixOS/nixpkgs/blob/d9d87c51960050e89c79e4025082ed965e770d68/nixos/modules/services/networking/firewall-nftables.nix#L100
fib saddr . mark . iif oif exists accept
}
}
table inet host {
chain input {
type filter hook input priority filter; policy drop;
iifname "lo" accept comment "allow loopback"
ct state invalid drop
ct state established,related accept
ip protocol icmp accept
ip6 nexthdr icmpv6 accept
# Allow SSH access.
tcp dport 22 accept comment "allow ssh access"
# Allow DHCP server access.
iifname $if_net0_3_ci_runner udp dport 67 accept comment "allow dhcp server access"
}
}
table ip v4nat {
chain prerouting {
type nat hook prerouting priority dstnat; policy accept;
}
chain postrouting {
type nat hook postrouting priority srcnat; policy accept;
oifname $if_net1_v4_wan masquerade
}
}
table inet forward {
chain forward {
type filter hook forward priority filter; policy drop;
ct state invalid drop
ct state established,related accept
# Allow internet access.
meta nfproto ipv6 iifname $lan_ifs oifname $if_net2_v6_wan accept comment "allow v6 internet access"
meta nfproto ipv4 iifname $lan_ifs oifname $if_net1_v4_wan accept comment "allow v4 internet access"
}
}