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nixos/nat: Don't flush tables, create subchains for autogenerated rules

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This commit is contained in:
William A. Kennington III 2014-09-16 16:56:08 -07:00
parent 194419244d
commit ae195727b7
1 changed files with 19 additions and 8 deletions
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27
nixos/modules/services/networking/nat.nix
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@ -13,38 +13,49 @@ let
dest = if cfg.externalIP == null then "-j MASQUERADE" else "-j SNAT --to-source ${cfg.externalIP}"; dest = if cfg.externalIP == null then "-j MASQUERADE" else "-j SNAT --to-source ${cfg.externalIP}";
flushNat = '' flushNat = ''
iptables -w -t nat -F PREROUTING iptables -w -t nat -D PREROUTING -j nixos-nat-pre 2>/dev/null|| true
iptables -w -t nat -F POSTROUTING iptables -w -t nat -F nixos-nat-pre 2>/dev/null || true
iptables -w -t nat -X iptables -w -t nat -X nixos-nat-pre 2>/dev/null || true
iptables -w -t nat -D POSTROUTING -j nixos-nat-post 2>/dev/null || true
iptables -w -t nat -F nixos-nat-post 2>/dev/null || true
iptables -w -t nat -X nixos-nat-post 2>/dev/null || true
''; '';
setupNat = '' setupNat = ''
# Create subchain where we store rules
iptables -w -t nat -N nixos-nat-pre
iptables -w -t nat -N nixos-nat-post
# We can't match on incoming interface in POSTROUTING, so # We can't match on incoming interface in POSTROUTING, so
# mark packets coming from the external interfaces. # mark packets coming from the external interfaces.
${concatMapStrings (iface: '' ${concatMapStrings (iface: ''
iptables -w -t nat -A PREROUTING \ iptables -w -t nat -A nixos-nat-pre \
-i '${iface}' -j MARK --set-mark 1 -i '${iface}' -j MARK --set-mark 1
'') cfg.internalInterfaces} '') cfg.internalInterfaces}
# NAT the marked packets. # NAT the marked packets.
${optionalString (cfg.internalInterfaces != []) '' ${optionalString (cfg.internalInterfaces != []) ''
iptables -w -t nat -A POSTROUTING -m mark --mark 1 \ iptables -w -t nat -A nixos-nat-post -m mark --mark 1 \
-o ${cfg.externalInterface} ${dest} -o ${cfg.externalInterface} ${dest}
''} ''}
# NAT packets coming from the internal IPs. # NAT packets coming from the internal IPs.
${concatMapStrings (range: '' ${concatMapStrings (range: ''
iptables -w -t nat -A POSTROUTING \ iptables -w -t nat -A nixos-nat-post \
-s '${range}' -o ${cfg.externalInterface} ${dest} -s '${range}' -o ${cfg.externalInterface} ${dest}
'') cfg.internalIPs} '') cfg.internalIPs}
# NAT from external ports to internal ports. # NAT from external ports to internal ports.
${concatMapStrings (fwd: '' ${concatMapStrings (fwd: ''
iptables -w -t nat -A PREROUTING \ iptables -w -t nat -A nixos-nat-pre \
-i ${cfg.externalInterface} -p tcp \ -i ${cfg.externalInterface} -p tcp \
--dport ${builtins.toString fwd.sourcePort} \ --dport ${builtins.toString fwd.sourcePort} \
-j DNAT --to-destination ${fwd.destination} -j DNAT --to-destination ${fwd.destination}
'') cfg.forwardPorts} '') cfg.forwardPorts}
# Append our chains to the nat tables
iptables -w -t nat -A PREROUTING -j nixos-nat-pre
iptables -w -t nat -A POSTROUTING -j nixos-nat-post
''; '';
in in
@ -157,7 +168,7 @@ in
extraStopCommands = flushNat; extraStopCommands = flushNat;
}; };
systemd.services = mkIf (!config.networking.firewall.enable) { nat = { systemd.services = mkIf (!config.networking.firewall.enable) { nat = {
description = "Network Address Translation"; description = "Network Address Translation";
wantedBy = [ "network.target" ]; wantedBy = [ "network.target" ];
after = [ "network-interfaces.target" "systemd-modules-load.service" ]; after = [ "network-interfaces.target" "systemd-modules-load.service" ];