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|
{ config, lib, ... }:
with lib;
let
cfg = config.networking.nat;
mkDest = externalIP:
if externalIP == null
then "masquerade"
else "snat ${externalIP}";
dest = mkDest cfg.externalIP;
destIPv6 = mkDest cfg.externalIPv6;
toNftSet = list: concatStringsSep ", " list;
toNftRange = ports: replaceStrings [ ":" ] [ "-" ] (toString ports);
ifaceSet = toNftSet (map (x: ''"${x}"'') cfg.internalInterfaces);
ipSet = toNftSet cfg.internalIPs;
ipv6Set = toNftSet cfg.internalIPv6s;
oifExpr = optionalString (cfg.externalInterface != null) ''oifname "${cfg.externalInterface}"'';
# Whether given IP (plus optional port) is an IPv6.
isIPv6 = ip: length (lib.splitString ":" ip) > 2;
splitIPPorts = IPPorts:
let
matchIP = if isIPv6 IPPorts then "[[]([0-9a-fA-F:]+)[]]" else "([0-9.]+)";
m = builtins.match "${matchIP}:([0-9-]+)" IPPorts;
in
{
IP = if m == null then throw "bad ip:ports `${IPPorts}'" else elemAt m 0;
ports = if m == null then throw "bad ip:ports `${IPPorts}'" else elemAt m 1;
};
mkTable = { ipVer, dest, ipSet, forwardPorts, dmzHost }:
let
# nftables maps for port forward
# l4proto . dport : addr . port
fwdMap = toNftSet (map
(fwd:
with (splitIPPorts fwd.destination);
"${fwd.proto} . ${toNftRange fwd.sourcePort} : ${IP} . ${ports}"
)
forwardPorts);
# nftables maps for port forward loopback dnat
# daddr . l4proto . dport : addr . port
fwdLoopDnatMap = toNftSet (concatMap
(fwd: map
(loopbackip:
with (splitIPPorts fwd.destination);
"${loopbackip} . ${fwd.proto} . ${toNftRange fwd.sourcePort} : ${IP} . ${ports}"
)
fwd.loopbackIPs)
forwardPorts);
# nftables set for port forward loopback snat
# daddr . l4proto . dport
fwdLoopSnatSet = toNftSet (map
(fwd:
with (splitIPPorts fwd.destination);
"${IP} . ${fwd.proto} . ${ports}"
)
forwardPorts);
in
''
chain pre {
type nat hook prerouting priority dstnat;
${optionalString (fwdMap != "") ''
iifname "${cfg.externalInterface}" meta l4proto { tcp, udp } dnat meta l4proto . th dport map { ${fwdMap} } comment "port forward"
''}
${optionalString (fwdLoopDnatMap != "") ''
meta l4proto { tcp, udp } dnat ${ipVer} daddr . meta l4proto . th dport map { ${fwdLoopDnatMap} } comment "port forward loopback from other hosts behind NAT"
''}
${optionalString (dmzHost != null) ''
iifname "${cfg.externalInterface}" dnat ${dmzHost} comment "dmz"
''}
}
chain post {
type nat hook postrouting priority srcnat;
${optionalString (ifaceSet != "") ''
iifname { ${ifaceSet} } ${oifExpr} ${dest} comment "from internal interfaces"
''}
${optionalString (ipSet != "") ''
${ipVer} saddr { ${ipSet} } ${oifExpr} ${dest} comment "from internal IPs"
''}
${optionalString (fwdLoopSnatSet != "") ''
iifname != "${cfg.externalInterface}" ${ipVer} daddr . meta l4proto . th dport { ${fwdLoopSnatSet} } masquerade comment "port forward loopback snat"
''}
}
chain out {
type nat hook output priority mangle;
${optionalString (fwdLoopDnatMap != "") ''
meta l4proto { tcp, udp } dnat ${ipVer} daddr . meta l4proto . th dport map { ${fwdLoopDnatMap} } comment "port forward loopback from the host itself"
''}
}
'';
in
{
config = mkIf (config.networking.nftables.enable && cfg.enable) {
assertions = [
{
assertion = cfg.extraCommands == "";
message = "extraCommands is incompatible with the nftables based nat module: ${cfg.extraCommands}";
}
{
assertion = cfg.extraStopCommands == "";
message = "extraStopCommands is incompatible with the nftables based nat module: ${cfg.extraStopCommands}";
}
{
assertion = config.networking.nftables.rulesetFile == null;
message = "networking.nftables.rulesetFile conflicts with the nat module";
}
];
networking.nftables.tables = {
"nixos-nat" = {
family = "ip";
content = mkTable {
ipVer = "ip";
inherit dest ipSet;
forwardPorts = filter (x: !(isIPv6 x.destination)) cfg.forwardPorts;
inherit (cfg) dmzHost;
};
};
"nixos-nat6" = mkIf cfg.enableIPv6 {
family = "ip6";
name = "nixos-nat";
content = mkTable {
ipVer = "ip6";
dest = destIPv6;
ipSet = ipv6Set;
forwardPorts = filter (x: isIPv6 x.destination) cfg.forwardPorts;
dmzHost = null;
};
};
};
networking.firewall.extraForwardRules = optionalString config.networking.firewall.filterForward ''
${optionalString (ifaceSet != "") ''
iifname { ${ifaceSet} } ${oifExpr} accept comment "from internal interfaces"
''}
${optionalString (ipSet != "") ''
ip saddr { ${ipSet} } ${oifExpr} accept comment "from internal IPs"
''}
${optionalString (ipv6Set != "") ''
ip6 saddr { ${ipv6Set} } ${oifExpr} accept comment "from internal IPv6s"
''}
'';
};
}
|