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nixos/{firewall, nat}: add a nftables based implementation

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Rvfg 2022-12-23 00:23:23 +08:00
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7
nixos/doc/manual/from_md/release-notes/rl-2305.section.xml
View file

@ -303,6 +303,13 @@
the Nix store. the Nix store.
</para> </para>
</listitem> </listitem>
<listitem>
<para>
The <literal>firewall</literal> and <literal>nat</literal>
module now has a nftables based implementation. Enable
<literal>networking.nftables</literal> to use it.
</para>
</listitem>
<listitem> <listitem>
<para> <para>
The <literal>services.fwupd</literal> module now allows The <literal>services.fwupd</literal> module now allows

2
nixos/doc/manual/release-notes/rl-2305.section.md
View file

@ -86,6 +86,8 @@ In addition to numerous new and upgraded packages, this release has the followin
- Resilio sync secret keys can now be provided using a secrets file at runtime, preventing these secrets from ending up in the Nix store. - Resilio sync secret keys can now be provided using a secrets file at runtime, preventing these secrets from ending up in the Nix store.
- The `firewall` and `nat` module now has a nftables based implementation. Enable `networking.nftables` to use it.
- The `services.fwupd` module now allows arbitrary daemon settings to be configured in a structured manner ([`services.fwupd.daemonSettings`](#opt-services.fwupd.daemonSettings)). - The `services.fwupd` module now allows arbitrary daemon settings to be configured in a structured manner ([`services.fwupd.daemonSettings`](#opt-services.fwupd.daemonSettings)).
- The `unifi-poller` package and corresponding NixOS module have been renamed to `unpoller` to match upstream. - The `unifi-poller` package and corresponding NixOS module have been renamed to `unpoller` to match upstream.

4
nixos/modules/module-list.nix
View file

@ -821,6 +821,8 @@
./services/networking/firefox-syncserver.nix ./services/networking/firefox-syncserver.nix
./services/networking/fireqos.nix ./services/networking/fireqos.nix
./services/networking/firewall.nix ./services/networking/firewall.nix
./services/networking/firewall-iptables.nix
./services/networking/firewall-nftables.nix
./services/networking/flannel.nix ./services/networking/flannel.nix
./services/networking/freenet.nix ./services/networking/freenet.nix
./services/networking/freeradius.nix ./services/networking/freeradius.nix
@ -891,6 +893,8 @@
./services/networking/namecoind.nix ./services/networking/namecoind.nix
./services/networking/nar-serve.nix ./services/networking/nar-serve.nix
./services/networking/nat.nix ./services/networking/nat.nix
./services/networking/nat-iptables.nix
./services/networking/nat-nftables.nix
./services/networking/nats.nix ./services/networking/nats.nix
./services/networking/nbd.nix ./services/networking/nbd.nix
./services/networking/ncdns.nix ./services/networking/ncdns.nix

7
nixos/modules/services/audio/roon-bridge.nix
View file

@ -53,13 +53,18 @@ in {
networking.firewall = mkIf cfg.openFirewall { networking.firewall = mkIf cfg.openFirewall {
allowedTCPPortRanges = [{ from = 9100; to = 9200; }]; allowedTCPPortRanges = [{ from = 9100; to = 9200; }];
allowedUDPPorts = [ 9003 ]; allowedUDPPorts = [ 9003 ];
extraCommands = '' extraCommands = optionalString (!config.networking.nftables.enable) ''
iptables -A INPUT -s 224.0.0.0/4 -j ACCEPT iptables -A INPUT -s 224.0.0.0/4 -j ACCEPT
iptables -A INPUT -d 224.0.0.0/4 -j ACCEPT iptables -A INPUT -d 224.0.0.0/4 -j ACCEPT
iptables -A INPUT -s 240.0.0.0/5 -j ACCEPT iptables -A INPUT -s 240.0.0.0/5 -j ACCEPT
iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT
iptables -A INPUT -m pkttype --pkt-type broadcast -j ACCEPT iptables -A INPUT -m pkttype --pkt-type broadcast -j ACCEPT
''; '';
extraInputRules = optionalString config.networking.nftables.enable ''
ip saddr { 224.0.0.0/4, 240.0.0.0/5 } accept
ip daddr 224.0.0.0/4 accept
pkttype { multicast, broadcast } accept
'';
}; };

7
nixos/modules/services/audio/roon-server.nix
View file

@ -58,7 +58,7 @@ in {
{ from = 30000; to = 30010; } { from = 30000; to = 30010; }
]; ];
allowedUDPPorts = [ 9003 ]; allowedUDPPorts = [ 9003 ];
extraCommands = '' extraCommands = optionalString (!config.networking.nftables.enable) ''
## IGMP / Broadcast ## ## IGMP / Broadcast ##
iptables -A INPUT -s 224.0.0.0/4 -j ACCEPT iptables -A INPUT -s 224.0.0.0/4 -j ACCEPT
iptables -A INPUT -d 224.0.0.0/4 -j ACCEPT iptables -A INPUT -d 224.0.0.0/4 -j ACCEPT
@ -66,6 +66,11 @@ in {
iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT
iptables -A INPUT -m pkttype --pkt-type broadcast -j ACCEPT iptables -A INPUT -m pkttype --pkt-type broadcast -j ACCEPT
''; '';
extraInputRules = optionalString config.networking.nftables.enable ''
ip saddr { 224.0.0.0/4, 240.0.0.0/5 } accept
ip daddr 224.0.0.0/4 accept
pkttype { multicast, broadcast } accept
'';
}; };

334
nixos/modules/services/networking/firewall-iptables.nix Normal file
View file

@ -0,0 +1,334 @@
/* This module enables a simple firewall.
The firewall can be customised in arbitrary ways by setting
‘networking.firewall.extraCommands’. For modularity, the firewall
uses several chains:
- ‘nixos-fw’ is the main chain for input packet processing.
- ‘nixos-fw-accept’ is called for accepted packets. If you want
additional logging, or want to reject certain packets anyway, you
can insert rules at the start of this chain.
- ‘nixos-fw-log-refuse’ and ‘nixos-fw-refuse’ are called for
refused packets. (The former jumps to the latter after logging
the packet.) If you want additional logging, or want to accept
certain packets anyway, you can insert rules at the start of
this chain.
- ‘nixos-fw-rpfilter’ is used as the main chain in the mangle table,
called from the built-in ‘PREROUTING’ chain. If the kernel
supports it and `cfg.checkReversePath` is set this chain will
perform a reverse path filter test.
- ‘nixos-drop’ is used while reloading the firewall in order to drop
all traffic. Since reloading isn't implemented in an atomic way
this'll prevent any traffic from leaking through while reloading
the firewall. However, if the reloading fails, the ‘firewall-stop’
script will be called which in return will effectively disable the
complete firewall (in the default configuration).
*/
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.networking.firewall;
inherit (config.boot.kernelPackages) kernel;
kernelHasRPFilter = ((kernel.config.isEnabled or (x: false)) "IP_NF_MATCH_RPFILTER") || (kernel.features.netfilterRPFilter or false);
helpers = import ./helpers.nix { inherit config lib; };
writeShScript = name: text:
let
dir = pkgs.writeScriptBin name ''
#! ${pkgs.runtimeShell} -e
${text}
'';
in
"${dir}/bin/${name}";
startScript = writeShScript "firewall-start" ''
${helpers}
# Flush the old firewall rules. !!! Ideally, updating the
# firewall would be atomic. Apparently that's possible
# with iptables-restore.
ip46tables -D INPUT -j nixos-fw 2> /dev/null || true
for chain in nixos-fw nixos-fw-accept nixos-fw-log-refuse nixos-fw-refuse; do
ip46tables -F "$chain" 2> /dev/null || true
ip46tables -X "$chain" 2> /dev/null || true
done
# The "nixos-fw-accept" chain just accepts packets.
ip46tables -N nixos-fw-accept
ip46tables -A nixos-fw-accept -j ACCEPT
# The "nixos-fw-refuse" chain rejects or drops packets.
ip46tables -N nixos-fw-refuse
${if cfg.rejectPackets then ''
# Send a reset for existing TCP connections that we've
# somehow forgotten about. Send ICMP "port unreachable"
# for everything else.
ip46tables -A nixos-fw-refuse -p tcp ! --syn -j REJECT --reject-with tcp-reset
ip46tables -A nixos-fw-refuse -j REJECT
'' else ''
ip46tables -A nixos-fw-refuse -j DROP
''}
# The "nixos-fw-log-refuse" chain performs logging, then
# jumps to the "nixos-fw-refuse" chain.
ip46tables -N nixos-fw-log-refuse
${optionalString cfg.logRefusedConnections ''
ip46tables -A nixos-fw-log-refuse -p tcp --syn -j LOG --log-level info --log-prefix "refused connection: "
''}
${optionalString (cfg.logRefusedPackets && !cfg.logRefusedUnicastsOnly) ''
ip46tables -A nixos-fw-log-refuse -m pkttype --pkt-type broadcast \
-j LOG --log-level info --log-prefix "refused broadcast: "
ip46tables -A nixos-fw-log-refuse -m pkttype --pkt-type multicast \
-j LOG --log-level info --log-prefix "refused multicast: "
''}
ip46tables -A nixos-fw-log-refuse -m pkttype ! --pkt-type unicast -j nixos-fw-refuse
${optionalString cfg.logRefusedPackets ''
ip46tables -A nixos-fw-log-refuse \
-j LOG --log-level info --log-prefix "refused packet: "
''}
ip46tables -A nixos-fw-log-refuse -j nixos-fw-refuse
# The "nixos-fw" chain does the actual work.
ip46tables -N nixos-fw
# Clean up rpfilter rules
ip46tables -t mangle -D PREROUTING -j nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t mangle -F nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t mangle -X nixos-fw-rpfilter 2> /dev/null || true
${optionalString (kernelHasRPFilter && (cfg.checkReversePath != false)) ''
# Perform a reverse-path test to refuse spoofers
# For now, we just drop, as the mangle table doesn't have a log-refuse yet
ip46tables -t mangle -N nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t mangle -A nixos-fw-rpfilter -m rpfilter --validmark ${optionalString (cfg.checkReversePath == "loose") "--loose"} -j RETURN
# Allows this host to act as a DHCP4 client without first having to use APIPA
iptables -t mangle -A nixos-fw-rpfilter -p udp --sport 67 --dport 68 -j RETURN
# Allows this host to act as a DHCPv4 server
iptables -t mangle -A nixos-fw-rpfilter -s 0.0.0.0 -d 255.255.255.255 -p udp --sport 68 --dport 67 -j RETURN
${optionalString cfg.logReversePathDrops ''
ip46tables -t mangle -A nixos-fw-rpfilter -j LOG --log-level info --log-prefix "rpfilter drop: "
''}
ip46tables -t mangle -A nixos-fw-rpfilter -j DROP
ip46tables -t mangle -A PREROUTING -j nixos-fw-rpfilter
''}
# Accept all traffic on the trusted interfaces.
${flip concatMapStrings cfg.trustedInterfaces (iface: ''
ip46tables -A nixos-fw -i ${iface} -j nixos-fw-accept
'')}
# Accept packets from established or related connections.
ip46tables -A nixos-fw -m conntrack --ctstate ESTABLISHED,RELATED -j nixos-fw-accept
# Accept connections to the allowed TCP ports.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (port:
''
ip46tables -A nixos-fw -p tcp --dport ${toString port} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedTCPPorts
) cfg.allInterfaces)}
# Accept connections to the allowed TCP port ranges.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (rangeAttr:
let range = toString rangeAttr.from + ":" + toString rangeAttr.to; in
''
ip46tables -A nixos-fw -p tcp --dport ${range} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedTCPPortRanges
) cfg.allInterfaces)}
# Accept packets on the allowed UDP ports.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (port:
''
ip46tables -A nixos-fw -p udp --dport ${toString port} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedUDPPorts
) cfg.allInterfaces)}
# Accept packets on the allowed UDP port ranges.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (rangeAttr:
let range = toString rangeAttr.from + ":" + toString rangeAttr.to; in
''
ip46tables -A nixos-fw -p udp --dport ${range} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedUDPPortRanges
) cfg.allInterfaces)}
# Optionally respond to ICMPv4 pings.
${optionalString cfg.allowPing ''
iptables -w -A nixos-fw -p icmp --icmp-type echo-request ${optionalString (cfg.pingLimit != null)
"-m limit ${cfg.pingLimit} "
}-j nixos-fw-accept
''}
${optionalString config.networking.enableIPv6 ''
# Accept all ICMPv6 messages except redirects and node
# information queries (type 139). See RFC 4890, section
# 4.4.
ip6tables -A nixos-fw -p icmpv6 --icmpv6-type redirect -j DROP
ip6tables -A nixos-fw -p icmpv6 --icmpv6-type 139 -j DROP
ip6tables -A nixos-fw -p icmpv6 -j nixos-fw-accept
# Allow this host to act as a DHCPv6 client
ip6tables -A nixos-fw -d fe80::/64 -p udp --dport 546 -j nixos-fw-accept
''}
${cfg.extraCommands}
# Reject/drop everything else.
ip46tables -A nixos-fw -j nixos-fw-log-refuse
# Enable the firewall.
ip46tables -A INPUT -j nixos-fw
'';
stopScript = writeShScript "firewall-stop" ''
${helpers}
# Clean up in case reload fails
ip46tables -D INPUT -j nixos-drop 2>/dev/null || true
# Clean up after added ruleset
ip46tables -D INPUT -j nixos-fw 2>/dev/null || true
${optionalString (kernelHasRPFilter && (cfg.checkReversePath != false)) ''
ip46tables -t mangle -D PREROUTING -j nixos-fw-rpfilter 2>/dev/null || true
''}
${cfg.extraStopCommands}
'';
reloadScript = writeShScript "firewall-reload" ''
${helpers}
# Create a unique drop rule
ip46tables -D INPUT -j nixos-drop 2>/dev/null || true
ip46tables -F nixos-drop 2>/dev/null || true
ip46tables -X nixos-drop 2>/dev/null || true
ip46tables -N nixos-drop
ip46tables -A nixos-drop -j DROP
# Don't allow traffic to leak out until the script has completed
ip46tables -A INPUT -j nixos-drop
${cfg.extraStopCommands}
if ${startScript}; then
ip46tables -D INPUT -j nixos-drop 2>/dev/null || true
else
echo "Failed to reload firewall... Stopping"
${stopScript}
exit 1
fi
'';
in
{
options = {
networking.firewall = {
extraCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -A INPUT -p icmp -j ACCEPT";
description = lib.mdDoc ''
Additional shell commands executed as part of the firewall
initialisation script. These are executed just before the
final "reject" firewall rule is added, so they can be used
to allow packets that would otherwise be refused.
This option only works with the iptables based firewall.
'';
};
extraStopCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -P INPUT ACCEPT";
description = lib.mdDoc ''
Additional shell commands executed as part of the firewall
shutdown script. These are executed just after the removal
of the NixOS input rule, or if the service enters a failed
state.
This option only works with the iptables based firewall.
'';
};
};
};
# FIXME: Maybe if `enable' is false, the firewall should still be
# built but not started by default?
config = mkIf (cfg.enable && config.networking.nftables.enable == false) {
assertions = [
# This is approximately "checkReversePath -> kernelHasRPFilter",
# but the checkReversePath option can include non-boolean
# values.
{
assertion = cfg.checkReversePath == false || kernelHasRPFilter;
message = "This kernel does not support rpfilter";
}
];
networking.firewall.checkReversePath = mkIf (!kernelHasRPFilter) (mkDefault false);
systemd.services.firewall = {
description = "Firewall";
wantedBy = [ "sysinit.target" ];
wants = [ "network-pre.target" ];
before = [ "network-pre.target" ];
after = [ "systemd-modules-load.service" ];
path = [ cfg.package ] ++ cfg.extraPackages;
# FIXME: this module may also try to load kernel modules, but
# containers don't have CAP_SYS_MODULE. So the host system had
# better have all necessary modules already loaded.
unitConfig.ConditionCapability = "CAP_NET_ADMIN";
unitConfig.DefaultDependencies = false;
reloadIfChanged = true;
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStart = "@${startScript} firewall-start";
ExecReload = "@${reloadScript} firewall-reload";
ExecStop = "@${stopScript} firewall-stop";
};
};
};
}

167
nixos/modules/services/networking/firewall-nftables.nix Normal file
View file

@ -0,0 +1,167 @@
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.networking.firewall;
ifaceSet = concatStringsSep ", " (
map (x: ''"${x}"'') cfg.trustedInterfaces
);
portsToNftSet = ports: portRanges: concatStringsSep ", " (
map (x: toString x) ports
++ map (x: "${toString x.from}-${toString x.to}") portRanges
);
in
{
options = {
networking.firewall = {
extraInputRules = mkOption {
type = types.lines;
default = "";
example = "ip6 saddr { fc00::/7, fe80::/10 } tcp dport 24800 accept";
description = lib.mdDoc ''
Additional nftables rules to be appended to the input-allow
chain.
This option only works with the nftables based firewall.
'';
};
extraForwardRules = mkOption {
type = types.lines;
default = "";
example = "iifname wg0 accept";
description = lib.mdDoc ''
Additional nftables rules to be appended to the forward-allow
chain.
This option only works with the nftables based firewall.
'';
};
};
};
config = mkIf (cfg.enable && config.networking.nftables.enable) {
assertions = [
{
assertion = cfg.extraCommands == "";
message = "extraCommands is incompatible with the nftables based firewall: ${cfg.extraCommands}";
}
{
assertion = cfg.extraStopCommands == "";
message = "extraStopCommands is incompatible with the nftables based firewall: ${cfg.extraStopCommands}";
}
{
assertion = cfg.pingLimit == null || !(hasPrefix "--" cfg.pingLimit);
message = "nftables syntax like \"2/second\" should be used in networking.firewall.pingLimit";
}
{
assertion = config.networking.nftables.rulesetFile == null;
message = "networking.nftables.rulesetFile conflicts with the firewall";
}
];
networking.nftables.ruleset = ''
table inet nixos-fw {
${optionalString (cfg.checkReversePath != false) ''
chain rpfilter {
type filter hook prerouting priority mangle + 10; policy drop;
meta nfproto ipv4 udp sport . udp dport { 67 . 68, 68 . 67 } accept comment "DHCPv4 client/server"
fib saddr . mark ${optionalString (cfg.checkReversePath != "loose") ". iif"} oif exists accept
${optionalString cfg.logReversePathDrops ''
log level info prefix "rpfilter drop: "
''}
}
''}
chain input {
type filter hook input priority filter; policy drop;
${optionalString (ifaceSet != "") ''iifname { ${ifaceSet} } accept comment "trusted interfaces"''}
# Some ICMPv6 types like NDP is untracked
ct state vmap { invalid : drop, established : accept, related : accept, * : jump input-allow } comment "*: new and untracked"
${optionalString cfg.logRefusedConnections ''
tcp flags syn / fin,syn,rst,ack log level info prefix "refused connection: "
''}
${optionalString (cfg.logRefusedPackets && !cfg.logRefusedUnicastsOnly) ''
pkttype broadcast log level info prefix "refused broadcast: "
pkttype multicast log level info prefix "refused multicast: "
''}
${optionalString cfg.logRefusedPackets ''
pkttype host log level info prefix "refused packet: "
''}
${optionalString cfg.rejectPackets ''
meta l4proto tcp reject with tcp reset
reject
''}
}
chain input-allow {
${concatStrings (mapAttrsToList (iface: cfg:
let
ifaceExpr = optionalString (iface != "default") "iifname ${iface}";
tcpSet = portsToNftSet cfg.allowedTCPPorts cfg.allowedTCPPortRanges;
udpSet = portsToNftSet cfg.allowedUDPPorts cfg.allowedUDPPortRanges;
in
''
${optionalString (tcpSet != "") "${ifaceExpr} tcp dport { ${tcpSet} } accept"}
${optionalString (udpSet != "") "${ifaceExpr} udp dport { ${udpSet} } accept"}
''
) cfg.allInterfaces)}
${optionalString cfg.allowPing ''
icmp type echo-request ${optionalString (cfg.pingLimit != null) "limit rate ${cfg.pingLimit}"} accept comment "allow ping"
''}
icmpv6 type != { nd-redirect, 139 } accept comment "Accept all ICMPv6 messages except redirects and node information queries (type 139). See RFC 4890, section 4.4."
ip6 daddr fe80::/64 udp dport 546 accept comment "DHCPv6 client"
${cfg.extraInputRules}
}
${optionalString cfg.filterForward ''
chain forward {
type filter hook forward priority filter; policy drop;
ct state vmap { invalid : drop, established : accept, related : accept, * : jump forward-allow } comment "*: new and untracked"
}
chain forward-allow {
icmpv6 type != { router-renumbering, 139 } accept comment "Accept all ICMPv6 messages except renumbering and node information queries (type 139). See RFC 4890, section 4.3."
ct status dnat accept comment "allow port forward"
${cfg.extraForwardRules}
}
''}
}
'';
};
}

580
nixos/modules/services/networking/firewall.nix
View file

@ -1,35 +1,3 @@
/* This module enables a simple firewall.
The firewall can be customised in arbitrary ways by setting
‘networking.firewall.extraCommands’. For modularity, the firewall
uses several chains:
- ‘nixos-fw’ is the main chain for input packet processing.
- ‘nixos-fw-accept’ is called for accepted packets. If you want
additional logging, or want to reject certain packets anyway, you
can insert rules at the start of this chain.
- ‘nixos-fw-log-refuse’ and ‘nixos-fw-refuse’ are called for
refused packets. (The former jumps to the latter after logging
the packet.) If you want additional logging, or want to accept
certain packets anyway, you can insert rules at the start of
this chain.
- ‘nixos-fw-rpfilter’ is used as the main chain in the mangle table,
called from the built-in ‘PREROUTING’ chain. If the kernel
supports it and `cfg.checkReversePath` is set this chain will
perform a reverse path filter test.
- ‘nixos-drop’ is used while reloading the firewall in order to drop
all traffic. Since reloading isn't implemented in an atomic way
this'll prevent any traffic from leaking through while reloading
the firewall. However, if the reloading fails, the ‘firewall-stop’
script will be called which in return will effectively disable the
complete firewall (in the default configuration).
*/
{ config, lib, pkgs, ... }: { config, lib, pkgs, ... }:
with lib; with lib;
@ -38,216 +6,6 @@ let
cfg = config.networking.firewall; cfg = config.networking.firewall;
inherit (config.boot.kernelPackages) kernel;
kernelHasRPFilter = ((kernel.config.isEnabled or (x: false)) "IP_NF_MATCH_RPFILTER") || (kernel.features.netfilterRPFilter or false);
helpers = import ./helpers.nix { inherit config lib; };
writeShScript = name: text: let dir = pkgs.writeScriptBin name ''
#! ${pkgs.runtimeShell} -e
${text}
''; in "${dir}/bin/${name}";
defaultInterface = { default = mapAttrs (name: value: cfg.${name}) commonOptions; };
allInterfaces = defaultInterface // cfg.interfaces;
startScript = writeShScript "firewall-start" ''
${helpers}
# Flush the old firewall rules. !!! Ideally, updating the
# firewall would be atomic. Apparently that's possible
# with iptables-restore.
ip46tables -D INPUT -j nixos-fw 2> /dev/null || true
for chain in nixos-fw nixos-fw-accept nixos-fw-log-refuse nixos-fw-refuse; do
ip46tables -F "$chain" 2> /dev/null || true
ip46tables -X "$chain" 2> /dev/null || true
done
# The "nixos-fw-accept" chain just accepts packets.
ip46tables -N nixos-fw-accept
ip46tables -A nixos-fw-accept -j ACCEPT
# The "nixos-fw-refuse" chain rejects or drops packets.
ip46tables -N nixos-fw-refuse
${if cfg.rejectPackets then ''
# Send a reset for existing TCP connections that we've
# somehow forgotten about. Send ICMP "port unreachable"
# for everything else.
ip46tables -A nixos-fw-refuse -p tcp ! --syn -j REJECT --reject-with tcp-reset
ip46tables -A nixos-fw-refuse -j REJECT
'' else ''
ip46tables -A nixos-fw-refuse -j DROP
''}
# The "nixos-fw-log-refuse" chain performs logging, then
# jumps to the "nixos-fw-refuse" chain.
ip46tables -N nixos-fw-log-refuse
${optionalString cfg.logRefusedConnections ''
ip46tables -A nixos-fw-log-refuse -p tcp --syn -j LOG --log-level info --log-prefix "refused connection: "
''}
${optionalString (cfg.logRefusedPackets && !cfg.logRefusedUnicastsOnly) ''
ip46tables -A nixos-fw-log-refuse -m pkttype --pkt-type broadcast \
-j LOG --log-level info --log-prefix "refused broadcast: "
ip46tables -A nixos-fw-log-refuse -m pkttype --pkt-type multicast \
-j LOG --log-level info --log-prefix "refused multicast: "
''}
ip46tables -A nixos-fw-log-refuse -m pkttype ! --pkt-type unicast -j nixos-fw-refuse
${optionalString cfg.logRefusedPackets ''
ip46tables -A nixos-fw-log-refuse \
-j LOG --log-level info --log-prefix "refused packet: "
''}
ip46tables -A nixos-fw-log-refuse -j nixos-fw-refuse
# The "nixos-fw" chain does the actual work.
ip46tables -N nixos-fw
# Clean up rpfilter rules
ip46tables -t mangle -D PREROUTING -j nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t mangle -F nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t mangle -X nixos-fw-rpfilter 2> /dev/null || true
${optionalString (kernelHasRPFilter && (cfg.checkReversePath != false)) ''
# Perform a reverse-path test to refuse spoofers
# For now, we just drop, as the mangle table doesn't have a log-refuse yet
ip46tables -t mangle -N nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t mangle -A nixos-fw-rpfilter -m rpfilter --validmark ${optionalString (cfg.checkReversePath == "loose") "--loose"} -j RETURN
# Allows this host to act as a DHCP4 client without first having to use APIPA
iptables -t mangle -A nixos-fw-rpfilter -p udp --sport 67 --dport 68 -j RETURN
# Allows this host to act as a DHCPv4 server
iptables -t mangle -A nixos-fw-rpfilter -s 0.0.0.0 -d 255.255.255.255 -p udp --sport 68 --dport 67 -j RETURN
${optionalString cfg.logReversePathDrops ''
ip46tables -t mangle -A nixos-fw-rpfilter -j LOG --log-level info --log-prefix "rpfilter drop: "
''}
ip46tables -t mangle -A nixos-fw-rpfilter -j DROP
ip46tables -t mangle -A PREROUTING -j nixos-fw-rpfilter
''}
# Accept all traffic on the trusted interfaces.
${flip concatMapStrings cfg.trustedInterfaces (iface: ''
ip46tables -A nixos-fw -i ${iface} -j nixos-fw-accept
'')}
# Accept packets from established or related connections.
ip46tables -A nixos-fw -m conntrack --ctstate ESTABLISHED,RELATED -j nixos-fw-accept
# Accept connections to the allowed TCP ports.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (port:
''
ip46tables -A nixos-fw -p tcp --dport ${toString port} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedTCPPorts
) allInterfaces)}
# Accept connections to the allowed TCP port ranges.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (rangeAttr:
let range = toString rangeAttr.from + ":" + toString rangeAttr.to; in
''
ip46tables -A nixos-fw -p tcp --dport ${range} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedTCPPortRanges
) allInterfaces)}
# Accept packets on the allowed UDP ports.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (port:
''
ip46tables -A nixos-fw -p udp --dport ${toString port} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedUDPPorts
) allInterfaces)}
# Accept packets on the allowed UDP port ranges.
${concatStrings (mapAttrsToList (iface: cfg:
concatMapStrings (rangeAttr:
let range = toString rangeAttr.from + ":" + toString rangeAttr.to; in
''
ip46tables -A nixos-fw -p udp --dport ${range} -j nixos-fw-accept ${optionalString (iface != "default") "-i ${iface}"}
''
) cfg.allowedUDPPortRanges
) allInterfaces)}
# Optionally respond to ICMPv4 pings.
${optionalString cfg.allowPing ''
iptables -w -A nixos-fw -p icmp --icmp-type echo-request ${optionalString (cfg.pingLimit != null)
"-m limit ${cfg.pingLimit} "
}-j nixos-fw-accept
''}
${optionalString config.networking.enableIPv6 ''
# Accept all ICMPv6 messages except redirects and node
# information queries (type 139). See RFC 4890, section
# 4.4.
ip6tables -A nixos-fw -p icmpv6 --icmpv6-type redirect -j DROP
ip6tables -A nixos-fw -p icmpv6 --icmpv6-type 139 -j DROP
ip6tables -A nixos-fw -p icmpv6 -j nixos-fw-accept
# Allow this host to act as a DHCPv6 client
ip6tables -A nixos-fw -d fe80::/64 -p udp --dport 546 -j nixos-fw-accept
''}
${cfg.extraCommands}
# Reject/drop everything else.
ip46tables -A nixos-fw -j nixos-fw-log-refuse
# Enable the firewall.
ip46tables -A INPUT -j nixos-fw
'';
stopScript = writeShScript "firewall-stop" ''
${helpers}
# Clean up in case reload fails
ip46tables -D INPUT -j nixos-drop 2>/dev/null || true
# Clean up after added ruleset
ip46tables -D INPUT -j nixos-fw 2>/dev/null || true
${optionalString (kernelHasRPFilter && (cfg.checkReversePath != false)) ''
ip46tables -t mangle -D PREROUTING -j nixos-fw-rpfilter 2>/dev/null || true
''}
${cfg.extraStopCommands}
'';
reloadScript = writeShScript "firewall-reload" ''
${helpers}
# Create a unique drop rule
ip46tables -D INPUT -j nixos-drop 2>/dev/null || true
ip46tables -F nixos-drop 2>/dev/null || true
ip46tables -X nixos-drop 2>/dev/null || true
ip46tables -N nixos-drop
ip46tables -A nixos-drop -j DROP
# Don't allow traffic to leak out until the script has completed
ip46tables -A INPUT -j nixos-drop
${cfg.extraStopCommands}
if ${startScript}; then
ip46tables -D INPUT -j nixos-drop 2>/dev/null || true
else
echo "Failed to reload firewall... Stopping"
${stopScript}
exit 1
fi
'';
canonicalizePortList = canonicalizePortList =
ports: lib.unique (builtins.sort builtins.lessThan ports); ports: lib.unique (builtins.sort builtins.lessThan ports);
@ -257,22 +15,20 @@ let
default = [ ]; default = [ ];
apply = canonicalizePortList; apply = canonicalizePortList;
example = [ 22 80 ]; example = [ 22 80 ];
description = description = lib.mdDoc ''
lib.mdDoc '' List of TCP ports on which incoming connections are
List of TCP ports on which incoming connections are accepted.
accepted. '';
'';
}; };
allowedTCPPortRanges = mkOption { allowedTCPPortRanges = mkOption {
type = types.listOf (types.attrsOf types.port); type = types.listOf (types.attrsOf types.port);
default = [ ]; default = [ ];
example = [ { from = 8999; to = 9003; } ]; example = [{ from = 8999; to = 9003; }];
description = description = lib.mdDoc ''
lib.mdDoc '' A range of TCP ports on which incoming connections are
A range of TCP ports on which incoming connections are accepted.
accepted. '';
'';
}; };
allowedUDPPorts = mkOption { allowedUDPPorts = mkOption {
@ -280,20 +36,18 @@ let
default = [ ]; default = [ ];
apply = canonicalizePortList; apply = canonicalizePortList;
example = [ 53 ]; example = [ 53 ];
description = description = lib.mdDoc ''
lib.mdDoc '' List of open UDP ports.
List of open UDP ports. '';
'';
}; };
allowedUDPPortRanges = mkOption { allowedUDPPortRanges = mkOption {
type = types.listOf (types.attrsOf types.port); type = types.listOf (types.attrsOf types.port);
default = [ ]; default = [ ];
example = [ { from = 60000; to = 61000; } ]; example = [{ from = 60000; to = 61000; }];
description = description = lib.mdDoc ''
lib.mdDoc '' Range of open UDP ports.
Range of open UDP ports. '';
'';
}; };
}; };
@ -301,240 +55,222 @@ in
{ {
###### interface
options = { options = {
networking.firewall = { networking.firewall = {
enable = mkOption { enable = mkOption {
type = types.bool; type = types.bool;
default = true; default = true;
description = description = lib.mdDoc ''
lib.mdDoc '' Whether to enable the firewall. This is a simple stateful
Whether to enable the firewall. This is a simple stateful firewall that blocks connection attempts to unauthorised TCP
firewall that blocks connection attempts to unauthorised TCP or UDP ports on this machine.
or UDP ports on this machine. It does not affect packet '';
forwarding.
'';
}; };
package = mkOption { package = mkOption {
type = types.package; type = types.package;
default = pkgs.iptables; default = if config.networking.nftables.enable then pkgs.nftables else pkgs.iptables;
defaultText = literalExpression "pkgs.iptables"; defaultText = literalExpression ''if config.networking.nftables.enable then "pkgs.nftables" else "pkgs.iptables"'';
example = literalExpression "pkgs.iptables-legacy"; example = literalExpression "pkgs.iptables-legacy";
description = description = lib.mdDoc ''
lib.mdDoc '' The package to use for running the firewall service.
The iptables package to use for running the firewall service. '';
'';
}; };
logRefusedConnections = mkOption { logRefusedConnections = mkOption {
type = types.bool; type = types.bool;
default = true; default = true;
description = description = lib.mdDoc ''
lib.mdDoc '' Whether to log rejected or dropped incoming connections.
Whether to log rejected or dropped incoming connections. Note: The logs are found in the kernel logs, i.e. dmesg
Note: The logs are found in the kernel logs, i.e. dmesg or journalctl -k.
or journalctl -k. '';
'';
}; };
logRefusedPackets = mkOption { logRefusedPackets = mkOption {
type = types.bool; type = types.bool;
default = false; default = false;
description = description = lib.mdDoc ''
lib.mdDoc '' Whether to log all rejected or dropped incoming packets.
Whether to log all rejected or dropped incoming packets. This tends to give a lot of log messages, so it's mostly
This tends to give a lot of log messages, so it's mostly useful for debugging.
useful for debugging. Note: The logs are found in the kernel logs, i.e. dmesg
Note: The logs are found in the kernel logs, i.e. dmesg or journalctl -k.
or journalctl -k. '';
'';
}; };
logRefusedUnicastsOnly = mkOption { logRefusedUnicastsOnly = mkOption {
type = types.bool; type = types.bool;
default = true; default = true;
description = description = lib.mdDoc ''
lib.mdDoc '' If {option}`networking.firewall.logRefusedPackets`
If {option}`networking.firewall.logRefusedPackets` and this option are enabled, then only log packets
and this option are enabled, then only log packets specifically directed at this machine, i.e., not broadcasts
specifically directed at this machine, i.e., not broadcasts or multicasts.
or multicasts. '';
'';
}; };
rejectPackets = mkOption { rejectPackets = mkOption {
type = types.bool; type = types.bool;
default = false; default = false;
description = description = lib.mdDoc ''
lib.mdDoc '' If set, refused packets are rejected rather than dropped
If set, refused packets are rejected rather than dropped (ignored). This means that an ICMP "port unreachable" error
(ignored). This means that an ICMP "port unreachable" error message is sent back to the client (or a TCP RST packet in
message is sent back to the client (or a TCP RST packet in case of an existing connection). Rejecting packets makes
case of an existing connection). Rejecting packets makes port scanning somewhat easier.
port scanning somewhat easier. '';
'';
}; };
trustedInterfaces = mkOption { trustedInterfaces = mkOption {
type = types.listOf types.str; type = types.listOf types.str;
default = [ ]; default = [ ];
example = [ "enp0s2" ]; example = [ "enp0s2" ];
description = description = lib.mdDoc ''
lib.mdDoc '' Traffic coming in from these interfaces will be accepted
Traffic coming in from these interfaces will be accepted unconditionally. Traffic from the loopback (lo) interface
unconditionally. Traffic from the loopback (lo) interface will always be accepted.
will always be accepted. '';
'';
}; };
allowPing = mkOption { allowPing = mkOption {
type = types.bool; type = types.bool;
default = true; default = true;
description = description = lib.mdDoc ''
lib.mdDoc '' Whether to respond to incoming ICMPv4 echo requests
Whether to respond to incoming ICMPv4 echo requests ("pings"). ICMPv6 pings are always allowed because the
("pings"). ICMPv6 pings are always allowed because the larger address space of IPv6 makes network scanning much
larger address space of IPv6 makes network scanning much less effective.
less effective. '';
'';
}; };
pingLimit = mkOption { pingLimit = mkOption {
type = types.nullOr (types.separatedString " "); type = types.nullOr (types.separatedString " ");
default = null; default = null;
example = "--limit 1/minute --limit-burst 5"; example = "--limit 1/minute --limit-burst 5";
description = description = lib.mdDoc ''
lib.mdDoc '' If pings are allowed, this allows setting rate limits on them.
If pings are allowed, this allows setting rate limits
on them. If non-null, this option should be in the form of For the iptables based firewall, it should be set like
flags like "--limit 1/minute --limit-burst 5" "--limit 1/minute --limit-burst 5".
'';
For the nftables based firewall, it should be set like
"2/second" or "1/minute burst 5 packets".
'';
}; };
checkReversePath = mkOption { checkReversePath = mkOption {
type = types.either types.bool (types.enum ["strict" "loose"]); type = types.either types.bool (types.enum [ "strict" "loose" ]);
default = kernelHasRPFilter; default = true;
defaultText = literalMD "`true` if supported by the chosen kernel"; defaultText = literalMD "`true` except if the iptables based firewall is in use and the kernel lacks rpfilter support";
example = "loose"; example = "loose";
description = description = lib.mdDoc ''
lib.mdDoc '' Performs a reverse path filter test on a packet. If a reply
Performs a reverse path filter test on a packet. If a reply to the packet would not be sent via the same interface that
to the packet would not be sent via the same interface that the packet arrived on, it is refused.
the packet arrived on, it is refused.
If using asymmetric routing or other complicated routing, set If using asymmetric routing or other complicated routing, set
this option to loose mode or disable it and setup your own this option to loose mode or disable it and setup your own
counter-measures. counter-measures.
This option can be either true (or "strict"), "loose" (only This option can be either true (or "strict"), "loose" (only
drop the packet if the source address is not reachable via any drop the packet if the source address is not reachable via any
interface) or false. Defaults to the value of interface) or false.
kernelHasRPFilter. '';
'';
}; };
logReversePathDrops = mkOption { logReversePathDrops = mkOption {
type = types.bool; type = types.bool;
default = false; default = false;
description = description = lib.mdDoc ''
lib.mdDoc '' Logs dropped packets failing the reverse path filter test if
Logs dropped packets failing the reverse path filter test if the option networking.firewall.checkReversePath is enabled.
the option networking.firewall.checkReversePath is enabled. '';
''; };
filterForward = mkOption {
type = types.bool;
default = false;
description = lib.mdDoc ''
Enable filtering in IP forwarding.
This option only works with the nftables based firewall.
'';
}; };
connectionTrackingModules = mkOption { connectionTrackingModules = mkOption {
type = types.listOf types.str; type = types.listOf types.str;
default = [ ]; default = [ ];
example = [ "ftp" "irc" "sane" "sip" "tftp" "amanda" "h323" "netbios_sn" "pptp" "snmp" ]; example = [ "ftp" "irc" "sane" "sip" "tftp" "amanda" "h323" "netbios_sn" "pptp" "snmp" ];
description = description = lib.mdDoc ''
lib.mdDoc '' List of connection-tracking helpers that are auto-loaded.
List of connection-tracking helpers that are auto-loaded. The complete list of possible values is given in the example.
The complete list of possible values is given in the example.
As helpers can pose as a security risk, it is advised to As helpers can pose as a security risk, it is advised to
set this to an empty list and disable the setting set this to an empty list and disable the setting
networking.firewall.autoLoadConntrackHelpers unless you networking.firewall.autoLoadConntrackHelpers unless you
know what you are doing. Connection tracking is disabled know what you are doing. Connection tracking is disabled
by default. by default.
Loading of helpers is recommended to be done through the Loading of helpers is recommended to be done through the
CT target. More info: CT target. More info:
https://home.regit.org/netfilter-en/secure-use-of-helpers/ https://home.regit.org/netfilter-en/secure-use-of-helpers/
''; '';
}; };
autoLoadConntrackHelpers = mkOption { autoLoadConntrackHelpers = mkOption {
type = types.bool; type = types.bool;
default = false; default = false;
description = description = lib.mdDoc ''
lib.mdDoc '' Whether to auto-load connection-tracking helpers.
Whether to auto-load connection-tracking helpers. See the description at networking.firewall.connectionTrackingModules
See the description at networking.firewall.connectionTrackingModules
(needs kernel 3.5+) (needs kernel 3.5+)
''; '';
};
extraCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -A INPUT -p icmp -j ACCEPT";
description =
lib.mdDoc ''
Additional shell commands executed as part of the firewall
initialisation script. These are executed just before the
final "reject" firewall rule is added, so they can be used
to allow packets that would otherwise be refused.
'';
}; };
extraPackages = mkOption { extraPackages = mkOption {
type = types.listOf types.package; type = types.listOf types.package;
default = [ ]; default = [ ];
example = literalExpression "[ pkgs.ipset ]"; example = literalExpression "[ pkgs.ipset ]";
description = description = lib.mdDoc ''
lib.mdDoc '' Additional packages to be included in the environment of the system
Additional packages to be included in the environment of the system as well as the path of networking.firewall.extraCommands.
as well as the path of networking.firewall.extraCommands. '';
'';
};
extraStopCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -P INPUT ACCEPT";
description =
lib.mdDoc ''
Additional shell commands executed as part of the firewall
shutdown script. These are executed just after the removal
of the NixOS input rule, or if the service enters a failed
state.
'';
}; };
interfaces = mkOption { interfaces = mkOption {
default = { }; default = { };
type = with types; attrsOf (submodule [ { options = commonOptions; } ]); type = with types; attrsOf (submodule [{ options = commonOptions; }]);
description = description = lib.mdDoc ''
lib.mdDoc '' Interface-specific open ports.
Interface-specific open ports. '';
''; };
allInterfaces = mkOption {
internal = true;
visible = false;
default = { default = mapAttrs (name: value: cfg.${name}) commonOptions; } // cfg.interfaces;
type = with types; attrsOf (submodule [{ options = commonOptions; }]);
description = lib.mdDoc ''
All open ports.
'';
}; };
} // commonOptions; } // commonOptions;
}; };
###### implementation
# FIXME: Maybe if `enable' is false, the firewall should still be
# built but not started by default?
config = mkIf cfg.enable { config = mkIf cfg.enable {
assertions = [
{
assertion = cfg.filterForward -> config.networking.nftables.enable;
message = "filterForward only works with the nftables based firewall";
}
];
networking.firewall.trustedInterfaces = [ "lo" ]; networking.firewall.trustedInterfaces = [ "lo" ];
environment.systemPackages = [ cfg.package ] ++ cfg.extraPackages; environment.systemPackages = [ cfg.package ] ++ cfg.extraPackages;
@ -545,40 +281,6 @@ in
options nf_conntrack nf_conntrack_helper=1 options nf_conntrack nf_conntrack_helper=1
''; '';
assertions = [
# This is approximately "checkReversePath -> kernelHasRPFilter",
# but the checkReversePath option can include non-boolean
# values.
{ assertion = cfg.checkReversePath == false || kernelHasRPFilter;
message = "This kernel does not support rpfilter"; }
];
systemd.services.firewall = {
description = "Firewall";
wantedBy = [ "sysinit.target" ];
wants = [ "network-pre.target" ];
before = [ "network-pre.target" ];
after = [ "systemd-modules-load.service" ];
path = [ cfg.package ] ++ cfg.extraPackages;
# FIXME: this module may also try to load kernel modules, but
# containers don't have CAP_SYS_MODULE. So the host system had
# better have all necessary modules already loaded.
unitConfig.ConditionCapability = "CAP_NET_ADMIN";
unitConfig.DefaultDependencies = false;
reloadIfChanged = true;
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStart = "@${startScript} firewall-start";
ExecReload = "@${reloadScript} firewall-reload";
ExecStop = "@${stopScript} firewall-stop";
};
};
}; };
} }

191
nixos/modules/services/networking/nat-iptables.nix Normal file
View file

@ -0,0 +1,191 @@
# This module enables Network Address Translation (NAT).
# XXX: todo: support multiple upstream links
# see http://yesican.chsoft.biz/lartc/MultihomedLinuxNetworking.html
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.networking.nat;
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; };
flushNat = ''
${helpers}
ip46tables -w -t nat -D PREROUTING -j nixos-nat-pre 2>/dev/null|| true
ip46tables -w -t nat -F nixos-nat-pre 2>/dev/null || true
ip46tables -w -t nat -X nixos-nat-pre 2>/dev/null || true
ip46tables -w -t nat -D POSTROUTING -j nixos-nat-post 2>/dev/null || true
ip46tables -w -t nat -F nixos-nat-post 2>/dev/null || true
ip46tables -w -t nat -X nixos-nat-post 2>/dev/null || true
ip46tables -w -t nat -D OUTPUT -j nixos-nat-out 2>/dev/null || true
ip46tables -w -t nat -F nixos-nat-out 2>/dev/null || true
ip46tables -w -t nat -X nixos-nat-out 2>/dev/null || true
${cfg.extraStopCommands}
'';
mkSetupNat = { iptables, dest, internalIPs, forwardPorts }: ''
# We can't match on incoming interface in POSTROUTING, so
# mark packets coming from the internal interfaces.
${concatMapStrings (iface: ''
${iptables} -w -t nat -A nixos-nat-pre \
-i '${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 \
${optionalString (cfg.externalInterface != null) "-o ${cfg.externalInterface}"} ${dest}
''}
# NAT packets coming from the internal IPs.
${concatMapStrings (range: ''
${iptables} -w -t nat -A nixos-nat-post \
-s '${range}' ${optionalString (cfg.externalInterface != null) "-o ${cfg.externalInterface}"} ${dest}
'') internalIPs}
# NAT from external ports to internal ports.
${concatMapStrings (fwd: ''
${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}
${concatMapStrings (loopbackip:
let
matchIP = if isIPv6 fwd.destination then "[[]([0-9a-fA-F:]+)[]]" else "([0-9.]+)";
m = builtins.match "${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 \
-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 \
-d ${loopbackip} -p ${fwd.proto} \
--dport ${builtins.toString fwd.sourcePort} \
-j DNAT --to-destination ${fwd.destination}
${iptables} -w -t nat -A nixos-nat-post \
-d ${destinationIP} -p ${fwd.proto} \
--dport ${destinationPorts} \
-j SNAT --to-source ${loopbackip}
'') fwd.loopbackIPs}
'') 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 \
-i ${toString cfg.externalInterface} -j DNAT \
--to-destination ${cfg.dmzHost}
''}
${cfg.extraCommands}
# Append our chains to the nat tables
ip46tables -w -t nat -A PREROUTING -j nixos-nat-pre
ip46tables -w -t nat -A POSTROUTING -j nixos-nat-post
ip46tables -w -t nat -A OUTPUT -j nixos-nat-out
'';
in
{
options = {
networking.nat.extraCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -A INPUT -p icmp -j ACCEPT";
description = lib.mdDoc ''
Additional shell commands executed as part of the nat
initialisation script.
This option is incompatible with the nftables based nat module.
'';
};
networking.nat.extraStopCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -D INPUT -p icmp -j ACCEPT || true";
description = lib.mdDoc ''
Additional shell commands executed as part of the nat
teardown script.
This option is incompatible with the nftables based nat module.
'';
};
};
config = mkIf (!config.networking.nftables.enable)
(mkMerge [
({ networking.firewall.extraCommands = mkBefore flushNat; })
(mkIf config.networking.nat.enable {
networking.firewall = mkIf config.networking.firewall.enable {
extraCommands = setupNat;
extraStopCommands = flushNat;
};
systemd.services = mkIf (!config.networking.firewall.enable) {
nat = {
description = "Network Address Translation";
wantedBy = [ "network.target" ];
after = [ "network-pre.target" "systemd-modules-load.service" ];
path = [ config.networking.firewall.package ];
unitConfig.ConditionCapability = "CAP_NET_ADMIN";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
};
script = flushNat + setupNat;
postStop = flushNat;
};
};
})
]);
}

184
nixos/modules/services/networking/nat-nftables.nix Normal file
View file

@ -0,0 +1,184 @@
{ config, lib, pkgs, ... }:
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 does not support both port and port range as values in a dnat map.
# e.g. "dnat th dport map { 80 : 10.0.0.1 . 80, 443 : 10.0.0.2 . 900-1000 }"
# So we split them.
fwdPorts = filter (x: length (splitString "-" x.destination) == 1) forwardPorts;
fwdPortsRange = filter (x: length (splitString "-" x.destination) > 1) forwardPorts;
# nftables maps for port forward
# l4proto . dport : addr . port
toFwdMap = forwardPorts: toNftSet (map
(fwd:
with (splitIPPorts fwd.destination);
"${fwd.proto} . ${toNftRange fwd.sourcePort} : ${IP} . ${ports}"
)
forwardPorts);
fwdMap = toFwdMap fwdPorts;
fwdRangeMap = toFwdMap fwdPortsRange;
# nftables maps for port forward loopback dnat
# daddr . l4proto . dport : addr . port
toFwdLoopDnatMap = forwardPorts: toNftSet (concatMap
(fwd: map
(loopbackip:
with (splitIPPorts fwd.destination);
"${loopbackip} . ${fwd.proto} . ${toNftRange fwd.sourcePort} : ${IP} . ${ports}"
)
fwd.loopbackIPs)
forwardPorts);
fwdLoopDnatMap = toFwdLoopDnatMap fwdPorts;
fwdLoopDnatRangeMap = toFwdLoopDnatMap fwdPortsRange;
# nftables set for port forward loopback snat
# daddr . l4proto . dport
fwdLoopSnatSet = toNftSet (map
(fwd:
with (splitIPPorts fwd.destination);
"${IP} . ${fwd.proto} . ${ports}"
)
forwardPorts);
in
''
chain pre {
type nat hook prerouting priority dstnat;
${optionalString (fwdMap != "") ''
iifname "${cfg.externalInterface}" dnat meta l4proto . th dport map { ${fwdMap} } comment "port forward"
''}
${optionalString (fwdRangeMap != "") ''
iifname "${cfg.externalInterface}" dnat meta l4proto . th dport map { ${fwdRangeMap} } comment "port forward"
''}
${optionalString (fwdLoopDnatMap != "") ''
dnat ${ipVer} daddr . meta l4proto . th dport map { ${fwdLoopDnatMap} } comment "port forward loopback from other hosts behind NAT"
''}
${optionalString (fwdLoopDnatRangeMap != "") ''
dnat ${ipVer} daddr . meta l4proto . th dport map { ${fwdLoopDnatRangeMap} } 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 != "") ''
dnat ${ipVer} daddr . meta l4proto . th dport map { ${fwdLoopDnatMap} } comment "port forward loopback from the host itself"
''}
${optionalString (fwdLoopDnatRangeMap != "") ''
dnat ${ipVer} daddr . meta l4proto . th dport map { ${fwdLoopDnatRangeMap} } 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.ruleset = ''
table ip nixos-nat {
${mkTable {
ipVer = "ip";
inherit dest ipSet;
forwardPorts = filter (x: !(isIPv6 x.destination)) cfg.forwardPorts;
inherit (cfg) dmzHost;
}}
}
${optionalString cfg.enableIPv6 ''
table ip6 nixos-nat {
${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"
''}
'';
};
}

341
nixos/modules/services/networking/nat.nix
View file

@ -7,219 +7,95 @@
with lib; with lib;
let let
cfg = config.networking.nat; cfg = config.networking.nat;
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; };
flushNat = ''
${helpers}
ip46tables -w -t nat -D PREROUTING -j nixos-nat-pre 2>/dev/null|| true
ip46tables -w -t nat -F nixos-nat-pre 2>/dev/null || true
ip46tables -w -t nat -X nixos-nat-pre 2>/dev/null || true
ip46tables -w -t nat -D POSTROUTING -j nixos-nat-post 2>/dev/null || true
ip46tables -w -t nat -F nixos-nat-post 2>/dev/null || true
ip46tables -w -t nat -X nixos-nat-post 2>/dev/null || true
ip46tables -w -t nat -D OUTPUT -j nixos-nat-out 2>/dev/null || true
ip46tables -w -t nat -F nixos-nat-out 2>/dev/null || true
ip46tables -w -t nat -X nixos-nat-out 2>/dev/null || true
${cfg.extraStopCommands}
'';
mkSetupNat = { iptables, dest, internalIPs, forwardPorts }: ''
# We can't match on incoming interface in POSTROUTING, so
# mark packets coming from the internal interfaces.
${concatMapStrings (iface: ''
${iptables} -w -t nat -A nixos-nat-pre \
-i '${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 \
${optionalString (cfg.externalInterface != null) "-o ${cfg.externalInterface}"} ${dest}
''}
# NAT packets coming from the internal IPs.
${concatMapStrings (range: ''
${iptables} -w -t nat -A nixos-nat-post \
-s '${range}' ${optionalString (cfg.externalInterface != null) "-o ${cfg.externalInterface}"} ${dest}
'') internalIPs}
# NAT from external ports to internal ports.
${concatMapStrings (fwd: ''
${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}
${concatMapStrings (loopbackip:
let
matchIP = if isIPv6 fwd.destination then "[[]([0-9a-fA-F:]+)[]]" else "([0-9.]+)";
m = builtins.match "${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 \
-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 \
-d ${loopbackip} -p ${fwd.proto} \
--dport ${builtins.toString fwd.sourcePort} \
-j DNAT --to-destination ${fwd.destination}
${iptables} -w -t nat -A nixos-nat-post \
-d ${destinationIP} -p ${fwd.proto} \
--dport ${destinationPorts} \
-j SNAT --to-source ${loopbackip}
'') fwd.loopbackIPs}
'') 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 \
-i ${toString cfg.externalInterface} -j DNAT \
--to-destination ${cfg.dmzHost}
''}
${cfg.extraCommands}
# Append our chains to the nat tables
ip46tables -w -t nat -A PREROUTING -j nixos-nat-pre
ip46tables -w -t nat -A POSTROUTING -j nixos-nat-post
ip46tables -w -t nat -A OUTPUT -j nixos-nat-out
'';
in in
{ {
###### interface
options = { options = {
networking.nat.enable = mkOption { networking.nat.enable = mkOption {
type = types.bool; type = types.bool;
default = false; default = false;
description = description = lib.mdDoc ''
lib.mdDoc '' Whether to enable Network Address Translation (NAT).
Whether to enable Network Address Translation (NAT). '';
'';
}; };
networking.nat.enableIPv6 = mkOption { networking.nat.enableIPv6 = mkOption {
type = types.bool; type = types.bool;
default = false; default = false;
description = description = lib.mdDoc ''
lib.mdDoc '' Whether to enable IPv6 NAT.
Whether to enable IPv6 NAT. '';
'';
}; };
networking.nat.internalInterfaces = mkOption { networking.nat.internalInterfaces = mkOption {
type = types.listOf types.str; type = types.listOf types.str;
default = []; default = [ ];
example = [ "eth0" ]; example = [ "eth0" ];
description = description = lib.mdDoc ''
lib.mdDoc '' The interfaces for which to perform NAT. Packets coming from
The interfaces for which to perform NAT. Packets coming from these interface and destined for the external interface will
these interface and destined for the external interface will be rewritten.
be rewritten. '';
'';
}; };
networking.nat.internalIPs = mkOption { networking.nat.internalIPs = mkOption {
type = types.listOf types.str; type = types.listOf types.str;
default = []; default = [ ];
example = [ "192.168.1.0/24" ]; example = [ "192.168.1.0/24" ];
description = description = lib.mdDoc ''
lib.mdDoc '' The IP address ranges for which to perform NAT. Packets
The IP address ranges for which to perform NAT. Packets coming from these addresses (on any interface) and destined
coming from these addresses (on any interface) and destined for the external interface will be rewritten.
for the external interface will be rewritten. '';
'';
}; };
networking.nat.internalIPv6s = mkOption { networking.nat.internalIPv6s = mkOption {
type = types.listOf types.str; type = types.listOf types.str;
default = []; default = [ ];
example = [ "fc00::/64" ]; example = [ "fc00::/64" ];
description = description = lib.mdDoc ''
lib.mdDoc '' The IPv6 address ranges for which to perform NAT. Packets
The IPv6 address ranges for which to perform NAT. Packets coming from these addresses (on any interface) and destined
coming from these addresses (on any interface) and destined for the external interface will be rewritten.
for the external interface will be rewritten. '';
'';
}; };
networking.nat.externalInterface = mkOption { networking.nat.externalInterface = mkOption {
type = types.nullOr types.str; type = types.nullOr types.str;
default = null; default = null;
example = "eth1"; example = "eth1";
description = description = lib.mdDoc ''
lib.mdDoc '' The name of the external network interface.
The name of the external network interface. '';
'';
}; };
networking.nat.externalIP = mkOption { networking.nat.externalIP = mkOption {
type = types.nullOr types.str; type = types.nullOr types.str;
default = null; default = null;
example = "203.0.113.123"; example = "203.0.113.123";
description = description = lib.mdDoc ''
lib.mdDoc '' The public IP address to which packets from the local
The public IP address to which packets from the local network are to be rewritten. If this is left empty, the
network are to be rewritten. If this is left empty, the IP address associated with the external interface will be
IP address associated with the external interface will be used.
used. '';
'';
}; };
networking.nat.externalIPv6 = mkOption { networking.nat.externalIPv6 = mkOption {
type = types.nullOr types.str; type = types.nullOr types.str;
default = null; default = null;
example = "2001:dc0:2001:11::175"; example = "2001:dc0:2001:11::175";
description = description = lib.mdDoc ''
lib.mdDoc '' The public IPv6 address to which packets from the local
The public IPv6 address to which packets from the local network are to be rewritten. If this is left empty, the
network are to be rewritten. If this is left empty, the IP address associated with the external interface will be
IP address associated with the external interface will be used.
used. '';
'';
}; };
networking.nat.forwardPorts = mkOption { networking.nat.forwardPorts = mkOption {
@ -246,122 +122,75 @@ in
loopbackIPs = mkOption { loopbackIPs = mkOption {
type = types.listOf types.str; type = types.listOf types.str;
default = []; default = [ ];
example = literalExpression ''[ "55.1.2.3" ]''; example = literalExpression ''[ "55.1.2.3" ]'';
description = lib.mdDoc "Public IPs for NAT reflection; for connections to `loopbackip:sourcePort' from the host itself and from other hosts behind NAT"; description = lib.mdDoc "Public IPs for NAT reflection; for connections to `loopbackip:sourcePort' from the host itself and from other hosts behind NAT";
}; };
}; };
}); });
default = []; default = [ ];
example = [ example = [
{ sourcePort = 8080; destination = "10.0.0.1:80"; proto = "tcp"; } { sourcePort = 8080; destination = "10.0.0.1:80"; proto = "tcp"; }
{ sourcePort = 8080; destination = "[fc00::2]:80"; proto = "tcp"; } { sourcePort = 8080; destination = "[fc00::2]:80"; proto = "tcp"; }
]; ];
description = description = lib.mdDoc ''
lib.mdDoc '' List of forwarded ports from the external interface to
List of forwarded ports from the external interface to internal destinations by using DNAT. Destination can be
internal destinations by using DNAT. Destination can be IPv6 if IPv6 NAT is enabled.
IPv6 if IPv6 NAT is enabled. '';
'';
}; };
networking.nat.dmzHost = mkOption { networking.nat.dmzHost = mkOption {
type = types.nullOr types.str; type = types.nullOr types.str;
default = null; default = null;
example = "10.0.0.1"; example = "10.0.0.1";
description = description = lib.mdDoc ''
lib.mdDoc '' The local IP address to which all traffic that does not match any
The local IP address to which all traffic that does not match any forwarding rule is forwarded.
forwarding rule is forwarded. '';
'';
};
networking.nat.extraCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -A INPUT -p icmp -j ACCEPT";
description =
lib.mdDoc ''
Additional shell commands executed as part of the nat
initialisation script.
'';
};
networking.nat.extraStopCommands = mkOption {
type = types.lines;
default = "";
example = "iptables -D INPUT -p icmp -j ACCEPT || true";
description =
lib.mdDoc ''
Additional shell commands executed as part of the nat
teardown script.
'';
}; };
}; };
###### implementation config = mkIf config.networking.nat.enable {
config = mkMerge [ assertions = [
{ networking.firewall.extraCommands = mkBefore flushNat; } {
(mkIf config.networking.nat.enable { 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";
}
{
assertion = (cfg.forwardPorts != [ ]) -> (cfg.externalInterface != null);
message = "networking.nat.forwardPorts requires networking.nat.externalInterface";
}
];
assertions = [ # Use the same iptables package as in config.networking.firewall.
{ assertion = cfg.enableIPv6 -> config.networking.enableIPv6; # When the firewall is enabled, this should be deduplicated without any
message = "networking.nat.enableIPv6 requires networking.enableIPv6"; # error.
} environment.systemPackages = [ config.networking.firewall.package ];
{ assertion = (cfg.dmzHost != null) -> (cfg.externalInterface != null);
message = "networking.nat.dmzHost requires networking.nat.externalInterface";
}
{ assertion = (cfg.forwardPorts != []) -> (cfg.externalInterface != null);
message = "networking.nat.forwardPorts requires networking.nat.externalInterface";
}
];
# Use the same iptables package as in config.networking.firewall. boot = {
# When the firewall is enabled, this should be deduplicated without any kernelModules = [ "nf_nat_ftp" ];
# error. kernel.sysctl = {
environment.systemPackages = [ config.networking.firewall.package ]; "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;
boot = { # Forward IPv6 packets.
kernelModules = [ "nf_nat_ftp" ]; "net.ipv6.conf.all.forwarding" = mkOverride 99 true;
kernel.sysctl = { "net.ipv6.conf.default.forwarding" = mkOverride 99 true;
"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;
};
}; };
};
networking.firewall = mkIf config.networking.firewall.enable { };
extraCommands = setupNat;
extraStopCommands = flushNat;
};
systemd.services = mkIf (!config.networking.firewall.enable) { nat = {
description = "Network Address Translation";
wantedBy = [ "network.target" ];
after = [ "network-pre.target" "systemd-modules-load.service" ];
path = [ config.networking.firewall.package ];
unitConfig.ConditionCapability = "CAP_NET_ADMIN";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
};
script = flushNat + setupNat;
postStop = flushNat;
}; };
})
];
} }

26
nixos/modules/services/networking/nftables.nix
View file

@ -12,11 +12,9 @@ in
default = false; default = false;
description = description =
lib.mdDoc '' lib.mdDoc ''
Whether to enable nftables. nftables is a Linux-based packet Whether to enable nftables and use nftables based firewall if enabled.
filtering framework intended to replace frameworks like iptables. nftables is a Linux-based packet filtering framework intended to
replace frameworks like iptables.
This conflicts with the standard networking firewall, so make sure to
disable it before using nftables.
Note that if you have Docker enabled you will not be able to use Note that if you have Docker enabled you will not be able to use
nftables without intervention. Docker uses iptables internally to nftables without intervention. Docker uses iptables internally to
@ -79,19 +77,17 @@ in
lib.mdDoc '' lib.mdDoc ''
The ruleset to be used with nftables. Should be in a format that The ruleset to be used with nftables. Should be in a format that
can be loaded using "/bin/nft -f". The ruleset is updated atomically. can be loaded using "/bin/nft -f". The ruleset is updated atomically.
This option conflicts with rulesetFile.
''; '';
}; };
networking.nftables.rulesetFile = mkOption { networking.nftables.rulesetFile = mkOption {
type = types.path; type = types.nullOr types.path;
default = pkgs.writeTextFile { default = null;
name = "nftables-rules";
text = cfg.ruleset;
};
defaultText = literalMD ''a file with the contents of {option}`networking.nftables.ruleset`'';
description = description =
lib.mdDoc '' lib.mdDoc ''
The ruleset file to be used with nftables. Should be in a format that The ruleset file to be used with nftables. Should be in a format that
can be loaded using "nft -f". The ruleset is updated atomically. can be loaded using "nft -f". The ruleset is updated atomically.
This option conflicts with ruleset and nftables based firewall.
''; '';
}; };
}; };
@ -99,10 +95,6 @@ in
###### implementation ###### implementation
config = mkIf cfg.enable { config = mkIf cfg.enable {
assertions = [{
assertion = config.networking.firewall.enable == false;
message = "You can not use nftables and iptables at the same time. networking.firewall.enable must be set to false.";
}];
boot.blacklistedKernelModules = [ "ip_tables" ]; boot.blacklistedKernelModules = [ "ip_tables" ];
environment.systemPackages = [ pkgs.nftables ]; environment.systemPackages = [ pkgs.nftables ];
networking.networkmanager.firewallBackend = mkDefault "nftables"; networking.networkmanager.firewallBackend = mkDefault "nftables";
@ -116,7 +108,9 @@ in
rulesScript = pkgs.writeScript "nftables-rules" '' rulesScript = pkgs.writeScript "nftables-rules" ''
#! ${pkgs.nftables}/bin/nft -f #! ${pkgs.nftables}/bin/nft -f
flush ruleset flush ruleset
include "${cfg.rulesetFile}" ${if cfg.rulesetFile != null then ''
include "${cfg.rulesetFile}"
'' else cfg.ruleset}
''; '';
in { in {
Type = "oneshot"; Type = "oneshot";

6
nixos/tests/all-tests.nix
View file

@ -211,7 +211,8 @@ in {
firefox-esr = handleTest ./firefox.nix { firefoxPackage = pkgs.firefox-esr; }; # used in `tested` job firefox-esr = handleTest ./firefox.nix { firefoxPackage = pkgs.firefox-esr; }; # used in `tested` job
firefox-esr-102 = handleTest ./firefox.nix { firefoxPackage = pkgs.firefox-esr-102; }; firefox-esr-102 = handleTest ./firefox.nix { firefoxPackage = pkgs.firefox-esr-102; };
firejail = handleTest ./firejail.nix {}; firejail = handleTest ./firejail.nix {};
firewall = handleTest ./firewall.nix {}; firewall = handleTest ./firewall.nix { nftables = false; };
firewall-nftables = handleTest ./firewall.nix { nftables = true; };
fish = handleTest ./fish.nix {}; fish = handleTest ./fish.nix {};
flannel = handleTestOn ["x86_64-linux"] ./flannel.nix {}; flannel = handleTestOn ["x86_64-linux"] ./flannel.nix {};
fluentd = handleTest ./fluentd.nix {}; fluentd = handleTest ./fluentd.nix {};
@ -412,6 +413,9 @@ in {
nat.firewall = handleTest ./nat.nix { withFirewall = true; }; nat.firewall = handleTest ./nat.nix { withFirewall = true; };
nat.firewall-conntrack = handleTest ./nat.nix { withFirewall = true; withConntrackHelpers = true; }; nat.firewall-conntrack = handleTest ./nat.nix { withFirewall = true; withConntrackHelpers = true; };
nat.standalone = handleTest ./nat.nix { withFirewall = false; }; nat.standalone = handleTest ./nat.nix { withFirewall = false; };
nat.nftables.firewall = handleTest ./nat.nix { withFirewall = true; nftables = true; };
nat.nftables.firewall-conntrack = handleTest ./nat.nix { withFirewall = true; withConntrackHelpers = true; nftables = true; };
nat.nftables.standalone = handleTest ./nat.nix { withFirewall = false; nftables = true; };
nats = handleTest ./nats.nix {}; nats = handleTest ./nats.nix {};
navidrome = handleTest ./navidrome.nix {}; navidrome = handleTest ./navidrome.nix {};
nbd = handleTest ./nbd.nix {}; nbd = handleTest ./nbd.nix {};

13
nixos/tests/firewall.nix
View file

@ -1,7 +1,7 @@
# Test the firewall module. # Test the firewall module.
import ./make-test-python.nix ( { pkgs, ... } : { import ./make-test-python.nix ( { pkgs, nftables, ... } : {
name = "firewall"; name = "firewall" + pkgs.lib.optionalString nftables "-nftables";
meta = with pkgs.lib.maintainers; { meta = with pkgs.lib.maintainers; {
maintainers = [ eelco ]; maintainers = [ eelco ];
}; };
@ -11,6 +11,7 @@ import ./make-test-python.nix ( { pkgs, ... } : {
{ ... }: { ... }:
{ networking.firewall.enable = true; { networking.firewall.enable = true;
networking.firewall.logRefusedPackets = true; networking.firewall.logRefusedPackets = true;
networking.nftables.enable = nftables;
services.httpd.enable = true; services.httpd.enable = true;
services.httpd.adminAddr = "foo@example.org"; services.httpd.adminAddr = "foo@example.org";
}; };
@ -23,6 +24,7 @@ import ./make-test-python.nix ( { pkgs, ... } : {
{ ... }: { ... }:
{ networking.firewall.enable = true; { networking.firewall.enable = true;
networking.firewall.rejectPackets = true; networking.firewall.rejectPackets = true;
networking.nftables.enable = nftables;
}; };
attacker = attacker =
@ -35,10 +37,11 @@ import ./make-test-python.nix ( { pkgs, ... } : {
testScript = { nodes, ... }: let testScript = { nodes, ... }: let
newSystem = nodes.walled2.config.system.build.toplevel; newSystem = nodes.walled2.config.system.build.toplevel;
unit = if nftables then "nftables" else "firewall";
in '' in ''
start_all() start_all()
walled.wait_for_unit("firewall") walled.wait_for_unit("${unit}")
walled.wait_for_unit("httpd") walled.wait_for_unit("httpd")
attacker.wait_for_unit("network.target") attacker.wait_for_unit("network.target")
@ -54,12 +57,12 @@ import ./make-test-python.nix ( { pkgs, ... } : {
walled.succeed("ping -c 1 attacker >&2") walled.succeed("ping -c 1 attacker >&2")
# If we stop the firewall, then connections should succeed. # If we stop the firewall, then connections should succeed.
walled.stop_job("firewall") walled.stop_job("${unit}")
attacker.succeed("curl -v http://walled/ >&2") attacker.succeed("curl -v http://walled/ >&2")
# Check whether activation of a new configuration reloads the firewall. # Check whether activation of a new configuration reloads the firewall.
walled.succeed( walled.succeed(
"${newSystem}/bin/switch-to-configuration test 2>&1 | grep -qF firewall.service" "${newSystem}/bin/switch-to-configuration test 2>&1 | grep -qF ${unit}.service"
) )
''; '';
}) })

12
nixos/tests/nat.nix
View file

@ -3,14 +3,16 @@
# client on the inside network, a server on the outside network, and a # client on the inside network, a server on the outside network, and a
# router connected to both that performs Network Address Translation # router connected to both that performs Network Address Translation
# for the client. # for the client.
import ./make-test-python.nix ({ pkgs, lib, withFirewall, withConntrackHelpers ? false, ... }: import ./make-test-python.nix ({ pkgs, lib, withFirewall, withConntrackHelpers ? false, nftables ? false, ... }:
let let
unit = if withFirewall then "firewall" else "nat"; unit = if nftables then "nftables" else (if withFirewall then "firewall" else "nat");
routerBase = routerBase =
lib.mkMerge [ lib.mkMerge [
{ virtualisation.vlans = [ 2 1 ]; { virtualisation.vlans = [ 2 1 ];
networking.firewall.enable = withFirewall; networking.firewall.enable = withFirewall;
networking.firewall.filterForward = nftables;
networking.nftables.enable = nftables;
networking.nat.internalIPs = [ "192.168.1.0/24" ]; networking.nat.internalIPs = [ "192.168.1.0/24" ];
networking.nat.externalInterface = "eth1"; networking.nat.externalInterface = "eth1";
} }
@ -21,7 +23,8 @@ import ./make-test-python.nix ({ pkgs, lib, withFirewall, withConntrackHelpers ?
]; ];
in in
{ {
name = "nat" + (if withFirewall then "WithFirewall" else "Standalone") name = "nat" + (lib.optionalString nftables "Nftables")
+ (if withFirewall then "WithFirewall" else "Standalone")
+ (lib.optionalString withConntrackHelpers "withConntrackHelpers"); + (lib.optionalString withConntrackHelpers "withConntrackHelpers");
meta = with pkgs.lib.maintainers; { meta = with pkgs.lib.maintainers; {
maintainers = [ eelco rob ]; maintainers = [ eelco rob ];
@ -34,6 +37,7 @@ import ./make-test-python.nix ({ pkgs, lib, withFirewall, withConntrackHelpers ?
{ virtualisation.vlans = [ 1 ]; { virtualisation.vlans = [ 1 ];
networking.defaultGateway = networking.defaultGateway =
(pkgs.lib.head nodes.router.config.networking.interfaces.eth2.ipv4.addresses).address; (pkgs.lib.head nodes.router.config.networking.interfaces.eth2.ipv4.addresses).address;
networking.nftables.enable = nftables;
} }
(lib.optionalAttrs withConntrackHelpers { (lib.optionalAttrs withConntrackHelpers {
networking.firewall.connectionTrackingModules = [ "ftp" ]; networking.firewall.connectionTrackingModules = [ "ftp" ];
@ -111,7 +115,7 @@ import ./make-test-python.nix ({ pkgs, lib, withFirewall, withConntrackHelpers ?
# FIXME: this should not be necessary, but nat.service is not started because # FIXME: this should not be necessary, but nat.service is not started because
# network.target is not triggered # network.target is not triggered
# (https://github.com/NixOS/nixpkgs/issues/16230#issuecomment-226408359) # (https://github.com/NixOS/nixpkgs/issues/16230#issuecomment-226408359)
${lib.optionalString (!withFirewall) '' ${lib.optionalString (!withFirewall && !nftables) ''
router.succeed("systemctl start nat.service") router.succeed("systemctl start nat.service")
''} ''}
client.succeed("curl --fail http://server/ >&2") client.succeed("curl --fail http://server/ >&2")