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nixos/nat: support IPv6 NAT

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Valérian Galliat 2015-02-06 23:55:51 +01:00 committed by Naïm Favier
parent 4e721164a8
commit b93a5a1746
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1 changed files with 97 additions and 23 deletions
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120
nixos/modules/services/networking/nat.nix
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@ -9,7 +9,14 @@ with lib;
let
cfg = config.networking.nat;
dest = if cfg.externalIP == null then "-j MASQUERADE" else "-j SNAT --to-source ${cfg.externalIP}";
mkDest = externalIP: if externalIP == null
then "-j MASQUERADE"
else "-j SNAT --to-source ${externalIP}";
dest = mkDest cfg.externalIP;
destIPv6 = mkDest cfg.externalIPv6;
# Whether given IP (plus optional port) is an IPv6.
isIPv6 = ip: builtins.length (lib.splitString ":" ip) > 2;
helpers = import ./helpers.nix { inherit config lib; };
@ -28,63 +35,80 @@ let
${cfg.extraStopCommands}
'';
setupNat = ''
${helpers}
# Create subchain where we store rules
ip46tables -w -t nat -N nixos-nat-pre
ip46tables -w -t nat -N nixos-nat-post
ip46tables -w -t nat -N nixos-nat-out
mkSetupNat = { iptables, dest, internalIPs, forwardPorts }: ''
# We can't match on incoming interface in POSTROUTING, so
# mark packets coming from the internal interfaces.
${concatMapStrings (iface: ''
iptables -w -t nat -A nixos-nat-pre \
${iptables} -w -t nat -A nixos-nat-pre \
-i '${iface}' -j MARK --set-mark 1
'') cfg.internalInterfaces}
# NAT the marked packets.
${optionalString (cfg.internalInterfaces != []) ''
iptables -w -t nat -A nixos-nat-post -m mark --mark 1 \
${iptables} -w -t nat -A nixos-nat-post -m mark --mark 1 \
${optionalString (cfg.externalInterface != null) "-o ${cfg.externalInterface}"} ${dest}
''}
# NAT packets coming from the internal IPs.
${concatMapStrings (range: ''
iptables -w -t nat -A nixos-nat-post \
${iptables} -w -t nat -A nixos-nat-post \
-s '${range}' ${optionalString (cfg.externalInterface != null) "-o ${cfg.externalInterface}"} ${dest}
'') cfg.internalIPs}
'') internalIPs}
# NAT from external ports to internal ports.
${concatMapStrings (fwd: ''
iptables -w -t nat -A nixos-nat-pre \
${iptables} -w -t nat -A nixos-nat-pre \
-i ${toString cfg.externalInterface} -p ${fwd.proto} \
--dport ${builtins.toString fwd.sourcePort} \
-j DNAT --to-destination ${fwd.destination}
${concatMapStrings (loopbackip:
let
m = builtins.match "([0-9.]+):([0-9-]+)" fwd.destination;
destinationIP = if (m == null) then throw "bad ip:ports `${fwd.destination}'" else elemAt m 0;
destinationPorts = if (m == null) then throw "bad ip:ports `${fwd.destination}'" else builtins.replaceStrings ["-"] [":"] (elemAt m 1);
matchIP = if isIPv6 fwd.destination then "[[]([0-9a-fA-F:]+)[]]" else "([0-9.]+)";
m = builtins.match "${matchIP}:([0-9-]+)" fwd.destination;
destinationIP = if m == null then throw "bad ip:ports `${fwd.destination}'" else elemAt m 0;
destinationPorts = if m == null then throw "bad ip:ports `${fwd.destination}'" else builtins.replaceStrings ["-"] [":"] (elemAt m 1);
in ''
# Allow connections to ${loopbackip}:${toString fwd.sourcePort} from the host itself
iptables -w -t nat -A nixos-nat-out \
${iptables} -w -t nat -A nixos-nat-out \
-d ${loopbackip} -p ${fwd.proto} \
--dport ${builtins.toString fwd.sourcePort} \
-j DNAT --to-destination ${fwd.destination}
# Allow connections to ${loopbackip}:${toString fwd.sourcePort} from other hosts behind NAT
iptables -w -t nat -A nixos-nat-pre \
${iptables} -w -t nat -A nixos-nat-pre \
-d ${loopbackip} -p ${fwd.proto} \
--dport ${builtins.toString fwd.sourcePort} \
-j DNAT --to-destination ${fwd.destination}
iptables -w -t nat -A nixos-nat-post \
${iptables} -w -t nat -A nixos-nat-post \
-d ${destinationIP} -p ${fwd.proto} \
--dport ${destinationPorts} \
-j SNAT --to-source ${loopbackip}
'') fwd.loopbackIPs}
'') cfg.forwardPorts}
'') forwardPorts}
'';
setupNat = ''
${helpers}
# Create subchains where we store rules
ip46tables -w -t nat -N nixos-nat-pre
ip46tables -w -t nat -N nixos-nat-post
ip46tables -w -t nat -N nixos-nat-out
${mkSetupNat {
iptables = "iptables";
inherit dest;
inherit (cfg) internalIPs;
forwardPorts = filter (x: !(isIPv6 x.destination)) cfg.forwardPorts;
}}
${optionalString cfg.enableIPv6 (mkSetupNat {
iptables = "ip6tables";
dest = destIPv6;
internalIPs = cfg.internalIPv6s;
forwardPorts = filter (x: isIPv6 x.destination) cfg.forwardPorts;
})}
${optionalString (cfg.dmzHost != null) ''
iptables -w -t nat -A nixos-nat-pre \
@ -117,6 +141,15 @@ in
'';
};
networking.nat.enableIPv6 = mkOption {
type = types.bool;
default = false;
description =
''
Whether to enable IPv6 NAT.
'';
};
networking.nat.internalInterfaces = mkOption {
type = types.listOf types.str;
default = [];
@ -141,6 +174,18 @@ in
'';
};
networking.nat.internalIPv6s = mkOption {
type = types.listOf types.str;
default = [];
example = [ "fc00::/64" ];
description =
''
The IPv6 address ranges for which to perform NAT. Packets
coming from these addresses (on any interface) and destined
for the external interface will be rewritten.
'';
};
networking.nat.externalInterface = mkOption {
type = types.nullOr types.str;
default = null;
@ -164,6 +209,19 @@ in
'';
};
networking.nat.externalIPv6 = mkOption {
type = types.nullOr types.str;
default = null;
example = "2001:dc0:2001:11::175";
description =
''
The public IPv6 address to which packets from the local
network are to be rewritten. If this is left empty, the
IP address associated with the external interface will be
used.
'';
};
networking.nat.forwardPorts = mkOption {
type = with types; listOf (submodule {
options = {
@ -176,7 +234,7 @@ in
destination = mkOption {
type = types.str;
example = "10.0.0.1:80";
description = "Forward connection to destination ip:port; to specify a port range, use ip:start-end";
description = "Forward connection to destination ip:port (or [ipv6]:port); to specify a port range, use ip:start-end";
};
proto = mkOption {
@ -195,11 +253,15 @@ in
};
});
default = [];
example = [ { sourcePort = 8080; destination = "10.0.0.1:80"; proto = "tcp"; } ];
example = [
{ sourcePort = 8080; destination = "10.0.0.1:80"; proto = "tcp"; }
{ sourcePort = 8080; destination = "[fc00::2]:80"; proto = "tcp"; }
];
description =
''
List of forwarded ports from the external interface to
internal destinations by using DNAT.
internal destinations by using DNAT. Destination can be
IPv6 if IPv6 NAT is enabled.
'';
};
@ -246,6 +308,9 @@ in
(mkIf config.networking.nat.enable {
assertions = [
{ assertion = cfg.enableIPv6 -> config.networking.enableIPv6;
message = "networking.nat.enableIPv6 requires networking.enableIPv6";
}
{ assertion = (cfg.dmzHost != null) -> (cfg.externalInterface != null);
message = "networking.nat.dmzHost requires networking.nat.externalInterface";
}
@ -261,6 +326,15 @@ in
kernel.sysctl = {
"net.ipv4.conf.all.forwarding" = mkOverride 99 true;
"net.ipv4.conf.default.forwarding" = mkOverride 99 true;
} // optionalAttrs cfg.enableIPv6 {
# Do not prevent IPv6 autoconfiguration.
# See <http://strugglers.net/~andy/blog/2011/09/04/linux-ipv6-router-advertisements-and-forwarding/>.
"net.ipv6.conf.all.accept_ra" = mkOverride 99 2;
"net.ipv6.conf.default.accept_ra" = mkOverride 99 2;
# Forward IPv6 packets.
"net.ipv6.conf.all.forwarding" = mkOverride 99 true;
"net.ipv6.conf.default.forwarding" = mkOverride 99 true;
};
};