summaryrefslogtreecommitdiffstats
path: root/doc/libnftables-json.adoc
blob: d985149a0af357680ae9ce5835768974a9dadcb1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
libnftables-json(5)
===================
Phil Sutter <phil@nwl.cc>
:doctype: manpage
:compat-mode!:

== NAME
libnftables-json - Supported JSON schema by libnftables

== SYNOPSIS
*{ "nftables": [* 'OBJECTS' *] }*

'OBJECTS' := 'LIST_OBJECTS' | 'CMD_OBJECTS'

'LIST_OBJECTS' := 'LIST_OBJECT' [ *,* 'LIST_OBJECTS' ]

'CMD_OBJECTS' := 'CMD_OBJECT' [ *,* 'CMD_OBJECTS' ]

'CMD_OBJECT' := *{* 'CMD'*:* 'LIST_OBJECT' *}* | 'METAINFO_OBJECT'

'CMD' := *"add"* | *"replace"* | *"create"* | *"insert"* | *"delete"* |
         *"list"* | *"reset"* | *"flush"* | *"rename"*

'LIST_OBJECT' := 'TABLE' | 'CHAIN' | 'RULE' | 'SET' | 'MAP' | 'ELEMENT' |
		 'FLOWTABLE' | 'COUNTER' | 'QUOTA' | 'CT_HELPER' | 'LIMIT' |
		 'METAINFO_OBJECT' | 'CT_TIMEOUT' | 'CT_EXPECTATION'

== DESCRIPTION
libnftables supports JSON formatted input and output. This is implemented as an
alternative frontend to the standard CLI syntax parser, therefore basic
behaviour is identical and, for (almost) any operation available in standard
syntax, there should be an equivalent one in JSON.

JSON input may be provided in a single string as parameter to
*nft_run_cmd_from_buffer()* or in a file identified by the 'filename' parameter
of the *nft_run_cmd_from_filename()* function.

JSON output has to be enabled via the *nft_ctx_output_set_json()* function, turning
library standard output into JSON format. Error output remains unaffected.

== GLOBAL STRUCTURE
In general, any JSON input or output is enclosed in an object with a single
property named 'nftables'. Its value is an array containing commands (for
input) or ruleset elements (for output).

A command is an object with a single property whose name identifies the command.
Its value is a ruleset element - basically identical to output elements, apart
from certain properties which may be interpreted differently or are required
when output generally omits them.

== METAINFO OBJECT
In output, the first object in an *nftables* array is a special one containing
library information. Its content is as follows:

[verse]
*{ "metainfo": {
	"version":* 'STRING'*,
	"release_name":* 'STRING'*,
	"json_schema_version":* 'NUMBER'
*}}*

The values of *version* and *release_name* properties are equal to the package
version and release name as printed by *nft -v*. The value of the
*json_schema_version* property is an integer indicating the schema version.

If supplied in library input, the parser will verify the *json_schema_version* value
to not exceed the internally hardcoded one (to make sure the given schema is
fully understood). In future, a lower number than the internal one may activate
compatibility mode to parse outdated and incompatible JSON input.

== COMMAND OBJECTS
The structure accepts an arbitrary amount of commands which are interpreted in
order of appearance. For instance, the following standard syntax input:

----
flush ruleset
add table inet mytable
add chain inet mytable mychain
add rule inet mytable mychain tcp dport 22 accept
----

translates into JSON as such:

----
{ "nftables": [
	{ "flush": { "ruleset": null }},
	{ "add": { "table": {
			"family": "inet",
			"name": "mytable"
	}}},
	{ "add": { "chain": {
			"family": "inet",
			"table": "mytable",
			"name": "mychain"
	}}},
	{ "add": { "rule": {
			"family": "inet",
			"table": "mytable",
			"chain": "mychain",
			"expr": [
				{ "match": {
					"op": "==",
					"left": { "payload": {
							"protocol": "tcp",
							"field": "dport"
					}},
					"right": 22
				}},
				{ "accept": null }
			]
	}}}
]}
----

=== ADD
[verse]
____
*{ "add":* 'ADD_OBJECT' *}*

'ADD_OBJECT' := 'TABLE' | 'CHAIN' | 'RULE' | 'SET' | 'MAP' | 'ELEMENT' |
                'FLOWTABLE' | 'COUNTER' | 'QUOTA' | 'CT_HELPER' | 'LIMIT' |
		'CT_TIMEOUT' | 'CT_EXPECTATION'
____

Add a new ruleset element to the kernel.

=== REPLACE
[verse]
*{ "replace":* 'RULE' *}*

Replace a rule. In 'RULE', the *handle* property is mandatory and identifies the
rule to be replaced.

=== CREATE
[verse]
*{ "create":* 'ADD_OBJECT' *}*

Identical to *add* command, but returns an error if the object already exists.

=== INSERT
[verse]
*{ "insert":* 'RULE' *}*

This command is identical to *add* for rules, but instead of appending the rule
to the chain by default, it inserts at first position. If a *handle* or *index*
property is given, the rule is inserted before the rule identified by those
properties.

=== DELETE
[verse]
*{ "delete":* 'ADD_OBJECT' *}*

Delete an object from the ruleset. Only the minimal number of properties
required to uniquely identify an object is generally needed in 'ADD_OBJECT'. For
most ruleset elements, this is *family* and *table* plus either *handle* or
*name* (except rules since they don't have a name).

=== LIST
[verse]
____
*{ "list":* 'LIST_OBJECT' *}*

'LIST_OBJECT' := 'TABLE' | 'TABLES' | 'CHAIN' | 'CHAINS' | 'SET' | 'SETS' |
                 'MAP' | 'MAPS | COUNTER' | 'COUNTERS' | 'QUOTA' | 'QUOTAS' |
                 'CT_HELPER' | 'CT_HELPERS' | 'LIMIT' | 'LIMITS' | 'RULESET' |
                 'METER' | 'METERS' | 'FLOWTABLE' | 'FLOWTABLES' |
                 'CT_TIMEOUT' | 'CT_EXPECTATION'
____

List ruleset elements. The plural forms are used to list all objects of that
kind, optionally filtered by *family* and for some, also *table*.

=== RESET
[verse]
____
*{ "reset":* 'RESET_OBJECT' *}*

'RESET_OBJECT' := 'COUNTER' | 'COUNTERS' | 'QUOTA' | 'QUOTAS'
____

Reset state in suitable objects, i.e. zero their internal counter.

=== FLUSH
[verse]
____
*{ "flush":* 'FLUSH_OBJECT' *}*

'FLUSH_OBJECT' := 'TABLE' | 'CHAIN' | 'SET' | 'MAP' | 'METER' | 'RULESET'
____

Empty contents in given object, e.g. remove all chains from given *table* or
remove all elements from given *set*.

=== RENAME
[verse]
*{ "rename":* 'CHAIN' *}*

Rename a chain. The new name is expected in a dedicated property named
*newname*.

== RULESET ELEMENTS

=== TABLE
[verse]
*{ "table": {
	"family":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'
*}}*

This object describes a table.

*family*::
	The table's family, e.g. *"ip"* or *"ip6"*.
*name*::
	The table's name.
*handle*::
	The table's handle. In input, it is used only in *delete* command as
	alternative to *name*.

=== CHAIN
[verse]
*{ "chain": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"newname":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"type":* 'STRING'*,
	"hook":* 'STRING'*,
	"prio":* 'NUMBER'*,
	"dev":* 'STRING'*,
	"policy":* 'STRING'
*}}*

This object describes a chain.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The chain's name.
*handle*::
	The chain's handle. In input, it is used only in *delete* command as
	alternative to *name*.
*newname*::
	A new name for the chain, only relevant in the *rename* command.

The following properties are required for base chains:

*type*::
	The chain's type.
*hook*::
	The chain's hook.
*prio*::
	The chain's priority.
*dev*::
	The chain's bound interface (if in the netdev family).
*policy*::
	The chain's policy.

=== RULE
[verse]
____
*{ "rule": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"chain":* 'STRING'*,
	"expr": [* 'STATEMENTS' *],
	"handle":* 'NUMBER'*,
	"index":* 'NUMBER'*,
	"comment":* 'STRING'
*}}*

'STATEMENTS' := 'STATEMENT' [*,* 'STATEMENTS' ]
____

This object describes a rule. Basic building blocks of rules are statements.
Each rule consists of at least one.

*family*::
	The table's family.
*table*::
	The table's name.
*chain*::
	The chain's name.
*expr*::
	An array of statements this rule consists of. In input, it is used in
	*add*/*insert*/*replace* commands only.
*handle*::
	The rule's handle. In *delete*/*replace* commands, it serves as an identifier
	of the rule to delete/replace. In *add*/*insert* commands, it serves as
	an identifier of an existing rule to append/prepend the rule to.
*index*::
	The rule's position for *add*/*insert* commands. It is used as an alternative to
	*handle* then.
*comment*::
	Optional rule comment.

=== SET / MAP
[verse]
____
*{ "set": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"type":* 'SET_TYPE'*,
	"policy":* 'SET_POLICY'*,
	"flags": [* 'SET_FLAG_LIST' *],
	"elem":* 'SET_ELEMENTS'*,
	"timeout":* 'NUMBER'*,
	"gc-interval":* 'NUMBER'*,
	"size":* 'NUMBER'
*}}*

*{ "map": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"type":* 'SET_TYPE'*,
	"map":* 'STRING'*,
	"policy":* 'SET_POLICY'*,
	"flags": [* 'SET_FLAG_LIST' *],
	"elem":* 'SET_ELEMENTS'*,
	"timeout":* 'NUMBER'*,
	"gc-interval":* 'NUMBER'*,
	"size":* 'NUMBER'
*}}*

'SET_TYPE' := 'STRING' | *[* 'SET_TYPE_LIST' *]*
'SET_TYPE_LIST' := 'STRING' [*,* 'SET_TYPE_LIST' ]
'SET_POLICY' := *"performance"* | *"memory"*
'SET_FLAG_LIST' := 'SET_FLAG' [*,* 'SET_FLAG_LIST' ]
'SET_FLAG' := *"constant"* | *"interval"* | *"timeout"*
'SET_ELEMENTS' := 'EXPRESSION' | *[* 'EXPRESSION_LIST' *]*
'EXPRESSION_LIST' := 'EXPRESSION' [*,* 'EXPRESSION_LIST' ]
____

These objects describe a named set or map. Maps are a special form of sets in
that they translate a unique key to a value.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The set's name.
*handle*::
	The set's handle. For input, it is used in the *delete* command only.
*type*::
	The set's datatype, see below.
*map*::
	Type of values this set maps to (i.e. this set is a map).
*policy*::
	The set's policy.
*flags*::
	The set's flags.
*elem*::
	Initial set element(s), see below.
*timeout*::
	Element timeout in seconds.
*gc-interval*::
	Garbage collector interval in seconds.
*size*::
	Maximum number of elements supported.

==== TYPE
The set type might be a string, such as *"ipv4_addr"* or an array
consisting of strings (for concatenated types).

==== ELEM
A single set element might be given as string, integer or boolean value for
simple cases. If additional properties are required, a formal *elem* object may
be used.

Multiple elements may be given in an array.

=== ELEMENT
[verse]
____
*{ "element": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"elem":* 'SET_ELEM'
*}}*

'SET_ELEM' := 'EXPRESSION' | *[* 'EXPRESSION_LIST' *]*
'EXPRESSION_LIST' := 'EXPRESSION' [*,* 'EXPRESSION' ]
____

Manipulate element(s) in a named set.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The set's name.
*elem*::
	See elem property of set object.

=== FLOWTABLE
[verse]
____
*{ "flowtable": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"hook":* 'STRING'*,
	"prio":* 'NUMBER'*,
	"dev":* 'FT_INTERFACE'
*}}*

'FT_INTERFACE' := 'STRING' | *[* 'FT_INTERFACE_LIST' *]*
'FT_INTERFACE_LIST' := 'STRING' [*,* 'STRING' ]
____

This object represents a named flowtable.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The flow table's name.
*handle*::
	The flow table's handle. In input, it is used by the *delete* command only.
*hook*::
	The flow table's hook.
*prio*::
	The flow table's priority.
*dev*::
	The flow table's interface(s).

=== COUNTER
[verse]
*{ "counter": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"packets":* 'NUMBER'*,
	"bytes":* 'NUMBER'
*}}*

This object represents a named counter.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The counter's name.
*handle*::
	The counter's handle. In input, it is used by the *delete* command only.
*packets*::
	Packet counter value.
*bytes*::
	Byte counter value.

=== QUOTA
[verse]
*{ "quota": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"bytes":* 'NUMBER'*,
	"used":* 'NUMBER'*,
	"inv":* 'BOOLEAN'
*}}*

This object represents a named quota.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The quota's name.
*handle*::
	The quota's handle. In input, it is used by the *delete* command only.
*bytes*::
	Quota threshold.
*used*::
	Quota used so far.
*inv*::
	If true, match if the quota has been exceeded.

=== CT HELPER
[verse]
____
*{ "ct helper": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* '... '*,
	"type":* 'STRING'*,
	"protocol":* 'CTH_PROTO'*,
	"l3proto":* 'STRING'
*}}*

'CTH_PROTO' := *"tcp"* | *"udp"*
____

This object represents a named conntrack helper.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The ct helper's name.
*handle*::
	The ct helper's handle. In input, it is used by the *delete* command only.
*type*::
	The ct helper type name, e.g. *"ftp"* or *"tftp"*.
*protocol*::
	The ct helper's layer 4 protocol.
*l3proto*::
	The ct helper's layer 3 protocol, e.g. *"ip"* or *"ip6"*.

=== LIMIT
[verse]
____
*{ "limit": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"rate":* 'NUMBER'*,
	"per":* 'STRING'*,
	"burst":* 'NUMBER'*,
	"unit":* 'LIMIT_UNIT'*,
	"inv":* 'BOOLEAN'
*}}*

'LIMIT_UNIT' := *"packets"* | *"bytes"*
____

This object represents a named limit.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The limit's name.
*handle*::
	The limit's handle. In input, it is used by the *delete* command only.
*rate*::
	The limit's rate value.
*per*::
	Time unit to apply the limit to, e.g. *"week"*, *"day"*, *"hour"*, etc.
	If omitted, defaults to *"second"*.
*burst*::
	The limit's burst value. If omitted, defaults to *0*.
*unit*::
	Unit of rate and burst values. If omitted, defaults to *"packets"*.
*inv*::
	If true, match if limit was exceeded. If omitted, defaults to *false*.

=== CT TIMEOUT
[verse]
____
*{ "ct timeout": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"protocol":* 'CTH_PROTO'*,
	"state":* 'STRING'*,
	"value:* 'NUMBER'*,
	"l3proto":* 'STRING'
*}}*

'CTH_PROTO' := *"tcp"* | *"udp"* | *"dccp"* | *"sctp"* | *"gre"* | *"icmpv6"* | *"icmp"* | *"generic"*
____

This object represents a named conntrack timeout policy.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The ct timeout object's name.
*handle*::
	The ct timeout object's handle. In input, it is used by *delete* command only.
*protocol*::
	The ct timeout object's layer 4 protocol.
*state*::
	The connection state name, e.g. *"established"*, *"syn_sent"*, *"close"* or
	*"close_wait"*, for which the timeout value has to be updated.
*value*::
	The updated timeout value for the specified connection state.
*l3proto*::
	The ct timeout object's layer 3 protocol, e.g. *"ip"* or *"ip6"*.

=== CT EXPECTATION
[verse]
____
*{ "ct expectation": {
	"family":* 'STRING'*,
	"table":* 'STRING'*,
	"name":* 'STRING'*,
	"handle":* 'NUMBER'*,
	"l3proto":* 'STRING'
	"protocol":* 'CTH_PROTO'*,
	"dport":* 'NUMBER'*,
	"timeout:* 'NUMBER'*,
	"size:* 'NUMBER'*,
*}}*

'CTH_PROTO' := *"tcp"* | *"udp"* | *"dccp"* | *"sctp"* | *"gre"* | *"icmpv6"* | *"icmp"* | *"generic"*
____

This object represents a named conntrack expectation.

*family*::
	The table's family.
*table*::
	The table's name.
*name*::
	The ct expectation object's name.
*handle*::
	The ct expectation object's handle. In input, it is used by *delete* command only.
*l3proto*::
	The ct expectation object's layer 3 protocol, e.g. *"ip"* or *"ip6"*.
*protocol*::
	The ct expectation object's layer 4 protocol.
*dport*::
	The destination port of the expected connection.
*timeout*::
	The time in millisecond that this expectation will live.
*size*::
	The maximum count of expectations to be living in the same time.

== STATEMENTS
Statements are the building blocks for rules. Each rule consists of at least
one.

=== VERDICT
[verse]
*{ "accept": null }*
*{ "drop": null }*
*{ "continue": null }*
*{ "return": null }*
*{ "jump": { "target": * 'STRING' *}}*
*{ "goto": { "target": * 'STRING' *}}*

A verdict either terminates packet traversal through the current chain or
delegates to a different one.

*jump* and *goto* statements expect a target chain name.

=== MATCH
[verse]
*{ "match": {
	"left":* 'EXPRESSION'*,
	"right":* 'EXPRESSION'*,
	"op":* 'STRING'
*}}*

This matches the expression on left hand side (typically a packet header or packet meta
info) with the expression on right hand side (typically a constant value). If the
statement evaluates to true, the next statement in this rule is considered. If not,
processing continues with the next rule in the same chain.

*left*::
	Left hand side of this match.
*right*::
	Right hand side of this match.
*op*::
	Operator indicating the type of comparison.

==== OPERATORS

[horizontal]
*&*:: Binary AND
*|*:: Binary OR
*^*:: Binary XOR
*<<*:: Left shift
*>>*:: Right shift
*==*:: Equal
*!=*:: Not equal
*<*:: Less than
*>*:: Greater than
*<=*:: Less than or equal to
*>=*:: Greater than or equal to
*in*:: Perform a lookup, i.e. test if bits on RHS are contained in LHS value

Unlike with the standard API, the operator is mandatory here. In the standard API,
a missing operator may be resolved in two ways, depending on the type of expression
on the RHS:

- If the RHS is a bitmask or a list of bitmasks, the expression resolves into a
  binary operation with the inequality operator, like this: '+LHS & RHS != 0+'.
- In any other case, the equality operator is simply inserted.

For the non-trivial first case, the JSON API supports the *in* operator.

=== COUNTER
[verse]
____
*{ "counter": {
	"packets":* 'NUMBER'*,
	"bytes":* 'NUMBER'
*}}*

*{ "counter":* 'STRING' *}*
____

This object represents a byte/packet counter. In input, no properties are
required. If given, they act as initial values for the counter.

The first form creates an anonymous counter which lives in the rule it appears
in. The second form specifies a reference to a named counter object.

*packets*::
	Packets counted.
*bytes*::
	Bytes counted.

=== MANGLE
[verse]
*{ "mangle": {
	"key":* 'EXPRESSION'*,
	"value":* 'EXPRESSION'
*}}*

This changes the packet data or meta info.

*key*::
	The packet data to be changed, given as an *exthdr*, *payload*, *meta*, *ct* or
	*ct helper* expression.
*value*::
	Value to change data to.

=== QUOTA
[verse]
____
*{ "quota": {
	"val":* 'NUMBER'*,
	"val_unit":* 'STRING'*,
	"used":* 'NUMBER'*,
	"used_unit":* 'STRING'*,
	"inv":* 'BOOLEAN'
*}}*

*{ "quota":* 'STRING' *}*
____

The first form creates an anonymous quota which lives in the rule it appears in.
The second form specifies a reference to a named quota object.

*val*::
	Quota value.
*val_unit*::
	Unit of *val*, e.g. *"kbytes"* or *"mbytes"*. If omitted, defaults to
	*"bytes"*.
*used*::
	Quota used so far. Optional on input. If given, serves as initial value.
*used_unit*::
	Unit of *used*. Defaults to *"bytes"*.
*inv*::
	If *true*, will match if quota was exceeded. Defaults to *false*.

=== LIMIT
[verse]
____
*{ "limit": {
	"rate":* 'NUMBER'*,
	"rate_unit":* 'STRING'*,
	"per":* 'STRING'*,
	"burst":* 'NUMBER'*,
	"burst_unit":* 'STRING'*,
	"inv":* 'BOOLEAN'
*}}*

*{ "limit":* 'STRING' *}*
____

The first form creates an anonymous limit which lives in the rule it appears in.
The second form specifies a reference to a named limit object.

*rate*::
	Rate value to limit to.
*rate_unit*::
	Unit of *rate*, e.g. *"packets"* or *"mbytes"*. Defaults to *"packets"*.
*per*::
	Denominator of *rate*, e.g. *"week"* or *"minutes"*.
*burst*::
	Burst value. Defaults to *0*.
*burst_unit*::
	Unit of *burst*, ignored if *rate_unit* is *"packets"*. Defaults to
	*"bytes"*.
*inv*::
	If *true*, matches if the limit was exceeded. Defaults to *false*.

=== FWD
[verse]
____
*{ "fwd": {
	"dev":* 'EXPRESSION'*,
	"family":* 'FWD_FAMILY'*,
	"addr":* 'EXPRESSION'
*}}*

'FWD_FAMILY' := *"ip"* | *"ip6"*
____

Forward a packet to a different destination.

*dev*::
	Interface to forward the packet on.
*family*::
	Family of *addr*.
*addr*::
	IP(v6) address to forward the packet to.

Both *family* and *addr* are optional, but if at least one is given, both must be present.

=== NOTRACK
[verse]
*{ "notrack": null }*

Disable connection tracking for the packet.

=== DUP
[verse]
*{ "dup": {
	"addr":* 'EXPRESSION'*,
	"dev":* 'EXPRESSION'
*}}*

Duplicate a packet to a different destination.

*addr*::
	Address to duplicate packet to.
*dev*::
	Interface to duplicate packet on. May be omitted to not specify an
	interface explicitly.

=== NETWORK ADDRESS TRANSLATION
[verse]
____
*{ "snat": {
	"addr":* 'EXPRESSION'*,
	"family":* 'STRING'*,
	"port":* 'EXPRESSION'*,
	"flags":* 'FLAGS'
*}}*

*{ "dnat": {
	"addr":* 'EXPRESSION'*,
	"family":* 'STRING'*,
	"port":* 'EXPRESSION'*,
	"flags":* 'FLAGS'
*}}*

*{ "masquerade": {
	"port":* 'EXPRESSION'*,
	"flags":* 'FLAGS'
*}}*

*{ "redirect": {
	"port":* 'EXPRESSION'*,
	"flags":* 'FLAGS'
*}}*

'FLAGS' := 'FLAG' | *[* 'FLAG_LIST' *]*
'FLAG_LIST' := 'FLAG' [*,* 'FLAG_LIST' ]
'FLAG' := *"random"* | *"fully-random"* | *"persistent"*
____

Perform Network Address Translation.

*addr*::
	Address to translate to.
*family*::
	Family of *addr*, either *ip* or *ip6*. Required in *inet*
	table family.
*port*::
	Port to translate to.
*flags*::
	Flag(s).

All properties are optional and default to none.

=== REJECT
[verse]
*{ "reject": {
	"type":* 'STRING'*,
	"expr":* 'EXPRESSION'
*}}*

Reject the packet and send the given error reply.

*type*::
	Type of reject, either *"tcp reset"*, *"icmpx"*, *"icmp"* or *"icmpv6"*.
*expr*::
	ICMP code to reject with.

All properties are optional.

=== SET
[verse]
*{ "set": {
	"op":* 'STRING'*,
	"elem":* 'EXPRESSION'*,
	"set":* 'STRING'
*}}*

Dynamically add/update elements to a set.

*op*::
	Operator on set, either *"add"* or *"update"*.
*elem*::
	Set element to add or update.
*set*::
	Set reference.

=== LOG
[verse]
____
*{ "log": {
	"prefix":* 'STRING'*,
	"group":* 'NUMBER'*,
	"snaplen":* 'NUMBER'*,
	"queue-threshold":* 'NUMBER'*,
	"level":* 'LEVEL'*,
	"flags":* 'FLAGS'
*}}*

'LEVEL' := *"emerg"* | *"alert"* | *"crit"* | *"err"* | *"warn"* | *"notice"* |
           *"info"* | *"debug"* | *"audit"*

'FLAGS' := 'FLAG' | *[* 'FLAG_LIST' *]*
'FLAG_LIST' := 'FLAG' [*,* 'FLAG_LIST' ]
'FLAG' := *"tcp sequence"* | *"tcp options"* | *"ip options"* | *"skuid"* |
          *"ether"* | *"all"*
____

Log the packet.

*prefix*::
	Prefix for log entries.
*group*::
	Log group.
*snaplen*::
	Snaplen for logging.
*queue-threshold*::
	Queue threshold.
*level*::
	Log level. Defaults to *"warn"*.
*flags*::
	Log flags.

All properties are optional.

=== CT HELPER
[verse]
*{ "ct helper":* 'EXPRESSION' *}*

Enable the specified conntrack helper for this packet.

*ct helper*::
	CT helper reference.

=== METER
[verse]
*{ "meter": {
	"name":* 'STRING'*,
	"key":* 'EXPRESSION'*,
	"stmt":* 'STATEMENT'
*}}*

Apply a given statement using a meter.

*name*::
	Meter name.
*key*::
	Meter key.
*stmt*::
	Meter statement.

=== QUEUE
[verse]
____
*{ "queue": {
	"num":* 'EXPRESSION'*,
	"flags":* 'FLAGS'
*}}*

'FLAGS' := 'FLAG' | *[* 'FLAG_LIST' *]*
'FLAG_LIST' := 'FLAG' [*,* 'FLAG_LIST' ]
'FLAG' := *"bypass"* | *"fanout"*
____

Queue the packet to userspace.

*num*::
	Queue number.
*flags*::
	Queue flags.

=== VERDICT MAP
[verse]
*{ "vmap": {
	"key":* 'EXPRESSION'*,
	"data":* 'EXPRESSION'
*}}*

Apply a verdict conditionally.

*key*::
	Map key.
*data*::
	Mapping expression consisting of value/verdict pairs.

=== CT COUNT
[verse]
*{ "ct count": {
	"val":* 'NUMBER'*,
	"inv":* 'BOOLEAN'
*}}*

Limit the number of connections using conntrack.

*val*::
	Connection count threshold.
*inv*::
	If *true*, match if *val* was exceeded. If omitted, defaults to
	*false*.

=== CT TIMEOUT
[verse]
*{ "ct timeout":* 'EXPRESSION' *}*

Assign connection tracking timeout policy.

*ct timeout*::
	CT timeout reference.

=== CT EXPECTATION
[verse]
*{ "ct expectation":* 'EXPRESSION' *}*

Assign connection tracking expectation.

*ct expectation*::
	CT expectation reference.

=== XT
[verse]
____
*{ "xt": {
	"type":* 'TYPENAME'*,
	"name":* 'STRING'
*}}*

'TYPENAME' := *match* | *target* | *watcher*
____

This represents an xt statement from xtables compat interface. It is a
fallback if translation is not available or not complete.

Seeing this means the ruleset (or parts of it) were created by *iptables-nft*
and one should use that to manage it.

*BEWARE:* nftables won't restore these statements.

== EXPRESSIONS
Expressions are the building blocks of (most) statements. In their most basic
form, they are just immediate values represented as a JSON string, integer or
boolean type.

=== IMMEDIATES
[verse]
'STRING'
'NUMBER'
'BOOLEAN'

Immediate expressions are typically used for constant values. For strings, there
are two special cases:

*@STRING*::
	The remaining part is taken as set name to create a set reference.
*\**::
	Construct a wildcard expression.

=== LISTS
[verse]
'ARRAY'

List expressions are constructed by plain arrays containing of an arbitrary
number of expressions.

=== CONCAT
[verse]
____
*{ "concat":* 'CONCAT' *}*

'CONCAT' := *[* 'EXPRESSION_LIST' *]*
'EXPRESSION_LIST' := 'EXPRESSION' [*,* 'EXPRESSION_LIST' ]
____

Concatenate several expressions.

=== SET
[verse]
____
*{ "set":* 'SET' *}*

'SET' := 'EXPRESSION' | *[* 'EXPRESSION_LIST' *]*
____

This object constructs an anonymous set. For mappings, an array of arrays with
exactly two elements is expected.

=== MAP
[verse]
*{ "map": {
	"key":* 'EXPRESSION'*,
	"data":* 'EXPRESSION'
*}}*

Map a key to a value.

*key*::
	Map key.
*data*::
	Mapping expression consisting of value/target pairs.

=== PREFIX
[verse]
*{ "prefix": {
	"addr":* 'EXPRESSION'*,
	"len":* 'NUMBER'
*}}*

Construct an IPv4 or IPv6 prefix consisting of address part in *addr* and prefix
length in *len*.

=== RANGE
[verse]
*{ "range": [* 'EXPRESSION' *,* 'EXPRESSION' *] }*

Construct a range of values. The first array item denotes the lower boundary,
the second one the upper boundary.

=== PAYLOAD
[verse]
____
*{ "payload": {
	"base":* 'BASE'*,
	"offset":* 'NUMBER'*,
	"len":* 'NUMBER'
*}}*

*{ "payload": {
	"protocol":* 'STRING'*,
	"field":* 'STRING'
*}}*

'BASE' := *"ll"* | *"nh"* | *"th"*
____

Construct a payload expression, i.e. a reference to a certain part of packet
data. The first form creates a raw payload expression to point at a random
number (*len*) of bytes at a certain offset (*offset*) from a given reference
point (*base*). The following *base* values are accepted:

*"ll"*::
	The offset is relative to Link Layer header start offset.
*"nh"*::
	The offset is relative to Network Layer header start offset.
*"th"*::
	The offset is relative to Transport Layer header start offset.

The second form allows one to reference a field by name (*field*) in a named packet
header (*protocol*).

=== EXTHDR
[verse]
*{ "exthdr": {
	"name":* 'STRING'*,
	"field":* 'STRING'*,
	"offset":* 'NUMBER'
*}}*

Create a reference to a field (*field*) in an IPv6 extension header (*name*).
*offset* is used only for *rt0* protocol.

If the *field* property is not given, the expression is to be used as a header
existence check in a *match* statement with a boolean on the right hand side.

=== TCP OPTION
[verse]
*{ "tcp option": {
	"name":* 'STRING'*,
	"field":* 'STRING'
*}}*

Create a reference to a field (*field*) of a TCP option header (*name*).

If the *field* property is not given, the expression is to be used as a TCP option
existence check in a *match* statement with a boolean on the right hand side.

=== SCTP CHUNK
[verse]
*{ "sctp chunk": {
	"name":* 'STRING'*,
	"field":* 'STRING'
*}}*

Create a reference to a field (*field*) of an SCTP chunk (*name*).

If the *field* property is not given, the expression is to be used as an SCTP
chunk existence check in a *match* statement with a boolean on the right hand
side.

=== META
[verse]
____
*{ "meta": {
	"key":* 'META_KEY'
*}}*

'META_KEY' := *"length"* | *"protocol"* | *"priority"* | *"random"* | *"mark"* |
              *"iif"* | *"iifname"* | *"iiftype"* | *"oif"* | *"oifname"* |
	      *"oiftype"* | *"skuid"* | *"skgid"* | *"nftrace"* |
	      *"rtclassid"* | *"ibriport"* | *"obriport"* | *"ibridgename"* |
	      *"obridgename"* | *"pkttype"* | *"cpu"* | *"iifgroup"* |
	      *"oifgroup"* | *"cgroup"* | *"nfproto"* | *"l4proto"* |
	      *"secpath"*
____

Create a reference to packet meta data.

=== RT
[verse]
____
*{ "rt": {
	"key":* 'RT_KEY'*,
	"family":* 'RT_FAMILY'
*}}*

'RT_KEY' := *"classid"* | *"nexthop"* | *"mtu"*
'RT_FAMILY' := *"ip"* | *"ip6"*
____

Create a reference to packet routing data.

The *family* property is optional and defaults to unspecified.

=== CT
[verse]
____
*{ "ct": {
	"key":* 'STRING'*,
	"family":* 'CT_FAMILY'*,
	"dir":* 'CT_DIRECTION'
*}}*

'CT_FAMILY' := *"ip"* | *"ip6"*
'CT_DIRECTION' := *"original"* | *"reply"*
____

Create a reference to packet conntrack data.

Some CT keys do not support a direction. In this case, *dir* must not be
given.

=== NUMGEN
[verse]
____
*{ "numgen": {
	"mode":* 'NG_MODE'*,
	"mod":* 'NUMBER'*,
	"offset":* 'NUMBER'
*}}*

'NG_MODE' := *"inc"* | *"random"*
____

Create a number generator.

The *offset* property is optional and defaults to 0.

=== HASH
[verse]
____
*{ "jhash": {
	"mod":* 'NUMBER'*,
	"offset":* 'NUMBER'*,
	"expr":* 'EXPRESSION'*,
	"seed":* 'NUMBER'
*}}*

*{ "symhash": {
	"mod":* 'NUMBER'*,
	"offset":* 'NUMBER'
*}}*
____

Hash packet data.

The *offset* and *seed* properties are optional and default to 0.

=== FIB
[verse]
____
*{ "fib": {
	"result":* 'FIB_RESULT'*,
	"flags":* 'FIB_FLAGS'
*}}*

'FIB_RESULT' := *"oif"* | *"oifname"* | *"type"*

'FIB_FLAGS' := 'FIB_FLAG' | *[* 'FIB_FLAG_LIST' *]*
'FIB_FLAG_LIST' := 'FIB_FLAG' [*,* 'FIB_FLAG_LIST' ]
'FIB_FLAG' := *"saddr"* | *"daddr"* | *"mark"* | *"iif"* | *"oif"*
____

Perform kernel Forwarding Information Base lookups.

=== BINARY OPERATION
[verse]
*{ "|": [* 'EXPRESSION'*,* 'EXPRESSION' *] }*
*{ "^": [* 'EXPRESSION'*,* 'EXPRESSION' *] }*
*{ "&": [* 'EXPRESSION'*,* 'EXPRESSION' *] }*
*{ "+<<+": [* 'EXPRESSION'*,* 'EXPRESSION' *] }*
*{ ">>": [* 'EXPRESSION'*,* 'EXPRESSION' *] }*

All binary operations expect an array of exactly two expressions, of which the
first element denotes the left hand side and the second one the right hand
side.

=== VERDICT
[verse]
*{ "accept": null }*
*{ "drop": null }*
*{ "continue": null }*
*{ "return": null }*
*{ "jump": { "target":* 'STRING' *}}*
*{ "goto": { "target":* 'STRING' *}}*

Same as the *verdict* statement, but for use in verdict maps.

*jump* and *goto* verdicts expect a target chain name.

=== ELEM
[verse]
*{ "elem": {
	"val":* 'EXPRESSION'*,
	"timeout":* 'NUMBER'*,
	"expires":* 'NUMBER'*,
	"comment":* 'STRING'
*}}*

Explicitly set element object, in case *timeout*, *expires* or *comment* are
desired. Otherwise, it may be replaced by the value of *val*.

=== SOCKET
[verse]
____
*{ "socket": {
	"key":* 'SOCKET_KEY'
*}}*

'SOCKET_KEY' := *"transparent"*
____

Construct a reference to packet's socket.

=== OSF
[verse]
____
*{ "osf": {
	"key":* 'OSF_KEY'*,
	"ttl":* 'OSF_TTL'
*}}*

'OSF_KEY' := *"name"*
'OSF_TTL' := *"loose"* | *"skip"*
____

Perform OS fingerprinting. This expression is typically used in the LHS of a *match*
statement.

*key*::
	Which part of the fingerprint info to match against. At this point, only
	the OS name is supported.
*ttl*::
	Define how the packet's TTL value is to be matched. This property is
	optional. If omitted, the TTL value has to match exactly. A value of *loose*
	accepts TTL values less than the fingerprint one. A value of *skip*
	omits TTL value comparison entirely.