nix-conf/modules/router/firewall.nix

222 lines
7.4 KiB
Nix

{ config, lib, pkgs, ... }:
let
vars = import ./vars.nix config;
links = vars.links;
ifs = vars.ifs;
pdFromWan = vars.pdFromWan;
nftIdentifiers = ''
define ZONE_WAN_IFS = { ${ifs.wan.name} }
define ZONE_LAN_IFS = {
${ifs.lan.name},
${ifs.lan10.name},
${ifs.lan20.name},
${ifs.lan30.name},
${ifs.lan40.name},
${ifs.lan50.name},
${ifs.wg0.name},
}
define OPNSENSE_NET6 = ${vars.extra.opnsense.net6}
define ZONE_LAN_EXTRA_NET6 = {
# TODO: reevaluate this statement
${ifs.lan20.net6}, # needed since packets can come in from wan on these addrs
$OPNSENSE_NET6,
}
define RFC1918 = { 10.0.0.0/8, 172.12.0.0/12, 192.168.0.0/16 }
define CLOUDFLARE_NET6 = {
# https://www.cloudflare.com/ips-v6
# TODO: figure out a better way to get addrs dynamically from url
# perhaps building a nixos module/package that fetches the ips?
2400:cb00::/32,
2606:4700::/32,
2803:f800::/32,
2405:b500::/32,
2405:8100::/32,
2a06:98c0::/29,
2c0f:f248::/32,
}
'';
in
{
networking.firewall.enable = false;
networking.nftables.enable = true;
# networking.nftables.ruleset = nftIdentifiers; #doesn't work because it's appended to the end
networking.nftables.tables.nat4 = {
family = "ip";
content = ''
${nftIdentifiers}
map port_forward {
type inet_proto . inet_service : ipv4_addr . inet_service
elements = {
tcp . 8006 : ${ifs.lan50.p4}.10 . 8006,
# opnsense vpn endpoints
# the plan is to maybe eventually move these to nixos
udp . 18596 : ${vars.extra.opnsense.addr4} . 18596,
udp . 48512 : ${vars.extra.opnsense.addr4} . 48512,
udp . 40993 : ${vars.extra.opnsense.addr4} . 40993,
udp . 45608 : ${vars.extra.opnsense.addr4} . 45608,
udp . 35848 : ${vars.extra.opnsense.addr4} . 35848,
udp . 48425 : ${vars.extra.opnsense.addr4} . 48425,
}
}
chain prerouting {
# Initial step, accept by default
type nat hook prerouting priority dstnat; policy accept;
# Port forwarding
fib daddr type local dnat ip to meta l4proto . th dport map @port_forward
}
chain postrouting {
# Last step, accept by default
type nat hook postrouting priority srcnat; policy accept;
# Masquerade LAN addrs
oifname $ZONE_WAN_IFS ip saddr $RFC1918 masquerade
}
'';
};
# Optional IPv6 masquerading (big L if enabled, don't forget to allow forwarding)
networking.nftables.tables.nat6 = {
family = "ip6";
enable = false;
content = ''
${nftIdentifiers}
chain postrouting {
type nat hook postrouting priority srcnat; policy accept;
oifname $ZONE_WAN_IFS ip6 saddr fd00::/8 masquerade
}
'';
};
networking.nftables.tables.firewall = {
family = "inet";
content = ''
${nftIdentifiers}
define ALLOWED_TCP_PORTS = { ssh }
define ALLOWED_UDP_PORTS = { ${toString vars.ifs.wg0.listenPort} }
define ALLOWED_TCP_LAN_PORTS = { ssh, https }
define ALLOWED_UDP_LAN_PORTS = { bootps, dhcpv6-server, domain, https }
set port_forward_v6 {
type inet_proto . ipv6_addr . inet_service
elements = {
# syncthing on alpina
tcp . ${ifs.lan.p6}::11:1 . 22000 ,
udp . ${ifs.lan.p6}::11:1 . 22000 ,
}
}
set cloudflare_forward_v6 {
type ipv6_addr
elements = {
${ifs.lan.p6}::11:1,
}
}
chain input {
type filter hook input priority filter; policy drop;
# Drop router adverts from self
# peculiarity due to wan and lan20 being bridged
# TODO: figure out a less jank way to do this
iifname $ZONE_WAN_IFS ip6 saddr ${links.lanLL} icmpv6 type nd-router-advert log prefix "self radvt: " drop
# iifname $ZONE_WAN_IFS ip6 saddr ${links.lanLL} ip6 nexthdr icmpv6 log prefix "self icmpv6: " drop
# iifname $ZONE_WAN_IFS ip6 saddr ${links.lanLL} log prefix "self llv6: " drop
# iifname $ZONE_WAN_IFS ip6 saddr ${links.lanLL} log drop
# iifname $ZONE_LAN_IFS ip6 saddr ${links.wanLL} log drop
# Allow established and related connections
# All icmp stuff should (theoretically) be handled by ct related
# https://serverfault.com/a/632363
ct state established,related accept
# However, that doesn't happen for router advertisements from what I can tell
# TODO: more testing
# Allow ICMPv6 on local addrs
ip6 nexthdr icmpv6 ip6 saddr { fe80::/10, ${pdFromWan}0::/60 } accept
ip6 nexthdr icmpv6 ip6 daddr fe80::/10 accept # TODO: not sure if necessary
# Allow all traffic from loopback interface
iif lo accept
# Allow DHCPv6 traffic
# I thought dhcpv6-client traffic would be accepted by established/related,
# but apparently not.
ip6 daddr { fe80::/10, ff02::/16 } th dport { dhcpv6-client, dhcpv6-server } accept
# Global input rules
tcp dport $ALLOWED_TCP_PORTS accept
udp dport $ALLOWED_UDP_PORTS accept
# WAN zone input rules
iifname $ZONE_WAN_IFS jump zone_wan_input
# LAN zone input rules
# iifname $ZONE_LAN_IFS accept
iifname $ZONE_LAN_IFS jump zone_lan_input
ip6 saddr $ZONE_LAN_EXTRA_NET6 jump zone_lan_input
# log
}
chain forward {
type filter hook forward priority filter; policy drop;
# Allow established and related connections
ct state established,related accept
# WAN zone forward rules
iifname $ZONE_WAN_IFS jump zone_wan_forward
# LAN zone forward rules
iifname $ZONE_LAN_IFS jump zone_lan_forward
ip6 saddr $ZONE_LAN_EXTRA_NET6 jump zone_lan_forward
}
chain zone_wan_input {
# Allow specific stuff from WAN
}
chain zone_wan_forward {
# Port forwarding
ct status dnat accept
# Allowed IPv6 ports
meta l4proto . ip6 daddr . th dport @port_forward_v6 accept
# Allowed IPv6 from cloudflare
ip6 saddr $CLOUDFLARE_NET6 ip6 daddr @cloudflare_forward_v6 th dport https accept
}
chain zone_lan_input {
# Allow all ICMPv6 from LAN
ip6 nexthdr icmpv6 accept
# Allow all ICMP from LAN
ip protocol icmp accept
# Allow specific services from LAN
tcp dport $ALLOWED_TCP_LAN_PORTS accept
udp dport $ALLOWED_UDP_LAN_PORTS accept
}
chain zone_lan_forward {
# Allow port forwarded targets
# ct status dnat accept
# Allow all traffic from LAN to WAN, except ULAs
oifname $ZONE_WAN_IFS ip6 saddr fd00::/8 drop # Not sure if needed
oifname $ZONE_WAN_IFS accept;
# Allow traffic between LANs
oifname $ZONE_LAN_IFS accept
}
chain output {
# Accept anything out of self by default
type filter hook output priority filter; policy accept;
# NAT reflection
# oif lo ip daddr != 127.0.0.0/8 dnat ip to meta l4proto . th dport map @port_forward_v4
}
'';
};
}