Reject conntrack fw DEST without an address in prerouting

internal/nftables/compiler.go

@@ -264,7 +264,7 @@ func (c *Compiler) compileConntrackPair(state *FirewallState, tag, chain string,
 	if ct.Action == config.ConntrackHelper {
 		return nil
 	}
-	if z, ok := c.cfg.Zones[dstZone]; ok && z.Type != config.ZoneFirewall && chain == "raw_prerouting" &&
+	if _, ok := c.cfg.Zones[dstZone]; ok && chain == "raw_prerouting" &&
 		(dstAddr == "" || strings.HasPrefix(dstAddr, "!")) {
 		return fmt.Errorf("conntrack DEST zone %q needs an address in prerouting", dstZone)
 	}

internal/nftables/compiler_test.go

@@ -583,7 +583,7 @@ func TestCompile_ConntrackNoTrack(t *testing.T) {
 			{
 				Action: config.ConntrackNoTrack,
 				Source: "net",
-				Dest:   "fw",
+				Dest:   "fw:192.0.2.1",
 				Proto:  "udp",
 				DPort:  config.PortSpec{"53"},
 			},
@@ -2433,7 +2433,7 @@ func TestCompile_ConntrackZones(t *testing.T) {
 	}{
 		{
 			name: "source zone matches iif",
-			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Dest: "fw", Proto: "udp", DPort: config.PortSpec{"53"}},
+			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Proto: "udp", DPort: config.PortSpec{"53"}},
 			want: map[string][]string{"raw_prerouting": {"iif=eth0"}},
 		},
 		{
@@ -2453,7 +2453,7 @@ func TestCompile_ConntrackZones(t *testing.T) {
 		},
 		{
 			name: "interface-less zone fails closed",
-			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "dmz", Dest: "fw"},
+			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "dmz"},
 			want: map[string][]string{},
 		},
 		{
@@ -2498,7 +2498,7 @@ func TestCompile_ConntrackZones(t *testing.T) {
 		},
 		{
 			name: "chain both with non-fw source emits prerouting only",
-			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Dest: "fw", Proto: "udp", DPort: config.PortSpec{"53"}, Chain: config.ConntrackBoth},
+			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Proto: "udp", DPort: config.PortSpec{"53"}, Chain: config.ConntrackBoth},
 			want: map[string][]string{"raw_prerouting": {"iif=eth0"}},
 		},
 		{
@@ -2508,12 +2508,12 @@ func TestCompile_ConntrackZones(t *testing.T) {
 		},
 		{
 			name: "negated addresses stay one AND-ed match",
-			ct:   config.ConntrackRule{Action: config.ConntrackDrop, Source: "net:!192.0.2.1,198.51.100.1", Dest: "fw"},
+			ct:   config.ConntrackRule{Action: config.ConntrackDrop, Source: "net:!192.0.2.1,198.51.100.1"},
 			want: map[string][]string{"raw_prerouting": {"iif=eth0 !saddr=192.0.2.1 !saddr=198.51.100.1"}},
 		},
 		{
 			name: "sport",
-			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Dest: "fw", Proto: "udp", SPort: config.PortSpec{"123"}},
+			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Proto: "udp", SPort: config.PortSpec{"123"}},
 			want: map[string][]string{"raw_prerouting": {"iif=eth0 sport=123"}},
 		},
 		{
@@ -2521,9 +2521,19 @@ func TestCompile_ConntrackZones(t *testing.T) {
 			ct:      config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Dest: "lan"},
 			wantErr: `conntrack DEST zone "lan" needs an address in prerouting`,
 		},
+		{
+			name:    "fw dest zone without address is rejected in prerouting",
+			ct:      config.ConntrackRule{Action: config.ConntrackDrop, Source: "net", Dest: "fw"},
+			wantErr: `conntrack DEST zone "fw" needs an address in prerouting`,
+		},
+		{
+			name: "fw dest zone with address matches daddr",
+			ct:   config.ConntrackRule{Action: config.ConntrackNoTrack, Source: "net", Dest: "fw:192.0.2.1"},
+			want: map[string][]string{"raw_prerouting": {"iif=eth0 daddr=192.0.2.1"}},
+		},
 		{
 			name: "unknown zone fails closed",
-			ct:   config.ConntrackRule{Action: config.ConntrackDrop, Source: "nte", Dest: "fw"},
+			ct:   config.ConntrackRule{Action: config.ConntrackDrop, Source: "nte"},
 			want: map[string][]string{},
 		},
 		{

tomswall.example.yaml

@@ -191,7 +191,7 @@ snat:
 # conntrack:
 #   - action: notrack
 #     source: net
-#     dest: fw
+#     dest: fw:203.0.113.1
 #     proto: udp
 #     dport: [53]
 #     comment: "Skip conntrack for DNS"