aboutsummaryrefslogtreecommitdiffstats
path: root/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-02.txt
blob: c4ec8c1125353500158cded7927402a467ae32a4 (plain) (blame)
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
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
Network Working Group                                          T. Ylonen
Internet-Draft                                               S. Lehtinen
Expires: April 1, 2002                  SSH Communications Security Corp
                                                            October 2001


                       SSH File Transfer Protocol
                    draft-ietf-secsh-filexfer-02.txt

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at http://
   www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on April 1, 2002.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   The SSH File Transfer Protocol provides secure file transfer
   functionality over any reliable data stream.  It is the standard file
   transfer protocol for use with the SSH2 protocol.  This document
   describes the file transfer protocol and its interface to the SSH2
   protocol suite.









Ylonen & Lehtinen         Expires April 1, 2002                 [Page 1]

Internet-Draft         SSH File Transfer Protocol           October 2001


Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.   Use with the SSH Connection Protocol . . . . . . . . . . . .   4
   3.   General Packet Format  . . . . . . . . . . . . . . . . . . .   5
   4.   Protocol Initialization  . . . . . . . . . . . . . . . . . .   7
   5.   File Attributes  . . . . . . . . . . . . . . . . . . . . . .   8
   6.   Requests From the Client to the Server . . . . . . . . . . .  10
   6.1  Request Synchronization and Reordering . . . . . . . . . . .  10
   6.2  File Names . . . . . . . . . . . . . . . . . . . . . . . . .  11
   6.3  Opening, Creating, and Closing Files . . . . . . . . . . . .  11
   6.4  Reading and Writing  . . . . . . . . . . . . . . . . . . . .  13
   6.5  Removing and Renaming Files  . . . . . . . . . . . . . . . .  14
   6.6  Creating and Deleting Directories  . . . . . . . . . . . . .  15
   6.7  Scanning Directories . . . . . . . . . . . . . . . . . . . .  15
   6.8  Retrieving File Attributes . . . . . . . . . . . . . . . . .  16
   6.9  Setting File Attributes  . . . . . . . . . . . . . . . . . .  17
   6.10 Dealing with Symbolic links  . . . . . . . . . . . . . . . .  18
   6.11 Canonicalizing the Server-Side Path Name . . . . . . . . . .  18
   7.   Responses from the Server to the Client  . . . . . . . . . .  20
   8.   Vendor-Specific Extensions . . . . . . . . . . . . . . . . .  24
   9.   Security Considerations  . . . . . . . . . . . . . . . . . .  25
   10.  Changes from previous protocol versions  . . . . . . . . . .  26
   10.1 Changes between versions 3 and 2 . . . . . . . . . . . . . .  26
   10.2 Changes between versions 2 and 1 . . . . . . . . . . . . . .  26
   10.3 Changes between versions 1 and 0 . . . . . . . . . . . . . .  26
   11.  Trademark Issues . . . . . . . . . . . . . . . . . . . . . .  27
        References . . . . . . . . . . . . . . . . . . . . . . . . .  28
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . .  28
        Full Copyright Statement . . . . . . . . . . . . . . . . . .  29





















Ylonen & Lehtinen         Expires April 1, 2002                 [Page 2]

Internet-Draft         SSH File Transfer Protocol           October 2001


1. Introduction

   This protocol provides secure file transfer (and more generally file
   system access) functionality over a reliable data stream, such as a
   channel in the SSH2 protocol [3].

   This protocol is designed so that it could be used to implement a
   secure remote file system service, as well as a secure file transfer
   service.

   This protocol assumes that it runs over a secure channel, and that
   the server has already authenticated the user at the client end, and
   that the identity of the client user is externally available to the
   server implementation.

   In general, this protocol follows a simple request-response model.
   Each request and response contains a sequence number and multiple
   requests may be pending simultaneously.  There are a relatively large
   number of different request messages, but a small number of possible
   response messages.  Each request has one or more response messages
   that may be returned in result (e.g., a read either returns data or
   reports error status).

   The packet format descriptions in this specification follow the
   notation presented in the secsh architecture draft.[3].

   Even though this protocol is described in the context of the SSH2
   protocol, this protocol is general and independent of the rest of the
   SSH2 protocol suite.  It could be used in a number of different
   applications, such as secure file transfer over TLS RFC 2246 [1] and
   transfer of management information in VPN applications.




















Ylonen & Lehtinen         Expires April 1, 2002                 [Page 3]

Internet-Draft         SSH File Transfer Protocol           October 2001


2. Use with the SSH Connection Protocol

   When used with the SSH2 Protocol suite, this protocol is intended to
   be used from the SSH Connection Protocol [5] as a subsystem, as
   described in section ``Starting a Shell or a Command''.  The
   subsystem name used with this protocol is "sftp".













































Ylonen & Lehtinen         Expires April 1, 2002                 [Page 4]

Internet-Draft         SSH File Transfer Protocol           October 2001


3. General Packet Format

    All packets transmitted over the secure connection are of the
   following format:

   	uint32             length
   	byte               type
   	byte[length - 1]   data payload

   That is, they are just data preceded by 32-bit length and 8-bit type
   fields.  The `length' is the length of the data area, and does not
   include the `length' field itself.  The format and interpretation of
   the data area depends on the packet type.

   All packet descriptions below only specify the packet type and the
   data that goes into the data field.  Thus, they should be prefixed by
   the `length' and `type' fields.

   The maximum size of a packet is in practice determined by the client
   (the maximum size of read or write requests that it sends, plus a few
   bytes of packet overhead).  All servers SHOULD support packets of at
   least 34000 bytes (where the packet size refers to the full length,
   including the header above).  This should allow for reads and writes
   of at most 32768 bytes.

   There is no limit on the number of outstanding (non-acknowledged)
   requests that the client may send to the server.  In practice this is
   limited by the buffering available on the data stream and the queuing
   performed by the server.  If the server's queues are full, it should
   not read any more data from the stream, and flow control will prevent
   the client from sending more requests.  Note, however, that while
   there is no restriction on the protocol level, the client's API may
   provide a limit in order to prevent infinite queuing of outgoing
   requests at the client.

















Ylonen & Lehtinen         Expires April 1, 2002                 [Page 5]

Internet-Draft         SSH File Transfer Protocol           October 2001


   The following values are defined for packet types.

   	#define SSH_FXP_INIT                1
   	#define SSH_FXP_VERSION             2
   	#define SSH_FXP_OPEN                3
   	#define SSH_FXP_CLOSE               4
   	#define SSH_FXP_READ                5
   	#define SSH_FXP_WRITE               6
   	#define SSH_FXP_LSTAT               7
   	#define SSH_FXP_FSTAT               8
   	#define SSH_FXP_SETSTAT             9
   	#define SSH_FXP_FSETSTAT           10
   	#define SSH_FXP_OPENDIR            11
   	#define SSH_FXP_READDIR            12
   	#define SSH_FXP_REMOVE             13
   	#define SSH_FXP_MKDIR              14
   	#define SSH_FXP_RMDIR              15
   	#define SSH_FXP_REALPATH           16
   	#define SSH_FXP_STAT               17
   	#define SSH_FXP_RENAME             18
   	#define SSH_FXP_READLINK           19
   	#define SSH_FXP_SYMLINK            20
   	#define SSH_FXP_STATUS            101
   	#define SSH_FXP_HANDLE            102
   	#define SSH_FXP_DATA              103
   	#define SSH_FXP_NAME              104
   	#define SSH_FXP_ATTRS             105
   	#define SSH_FXP_EXTENDED          200
   	#define SSH_FXP_EXTENDED_REPLY    201

   Additional packet types should only be defined if the protocol
   version number (see Section ``Protocol Initialization'') is
   incremented, and their use MUST be negotiated using the version
   number.  However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY
   packets can be used to implement vendor-specific extensions.  See
   Section ``Vendor-Specific-Extensions'' for more details.















Ylonen & Lehtinen         Expires April 1, 2002                 [Page 6]

Internet-Draft         SSH File Transfer Protocol           October 2001


4. Protocol Initialization

   When the file transfer protocol starts, it first sends a SSH_FXP_INIT
   (including its version number) packet to the server.  The server
   responds with a SSH_FXP_VERSION packet, supplying the lowest of its
   own and the client's version number.  Both parties should from then
   on adhere to particular version of the protocol.

   The SSH_FXP_INIT packet (from client to server) has the following
   data:

   	uint32 version
   	<extension data>

    The SSH_FXP_VERSION packet (from server to client) has the following
   data:

   	uint32 version
   	<extension data>

   The version number of the protocol specified in this document is 3.
   The version number should be incremented for each incompatible
   revision of this protocol.

    The extension data in the above packets may be empty, or may be a
   sequence of

   	string extension_name
   	string extension_data

   pairs (both strings MUST always be present if one is, but the
   `extension_data' string may be of zero length).  If present, these
   strings indicate extensions to the baseline protocol.  The
   `extension_name' field(s) identify the name of the extension.  The
   name should be of the form "name@domain", where the domain is the DNS
   domain name of the organization defining the extension.  Additional
   names that are not of this format may be defined later by the IETF.
   Implementations MUST silently ignore any extensions whose name they
   do not recognize.












Ylonen & Lehtinen         Expires April 1, 2002                 [Page 7]

Internet-Draft         SSH File Transfer Protocol           October 2001


5. File Attributes

   A new compound data type is defined for encoding file attributes.  It
   is basically just a combination of elementary types, but is defined
   once because of the non-trivial description of the fields and to
   ensure maintainability.

   The same encoding is used both when returning file attributes from
   the server and when sending file attributes to the server.  When
   sending it to the server, the flags field specifies which attributes
   are included, and the server will use default values for the
   remaining attributes (or will not modify the values of remaining
   attributes).  When receiving attributes from the server, the flags
   specify which attributes are included in the returned data.  The
   server normally returns all attributes it knows about.

   	uint32   flags
   	uint64   size           present only if flag SSH_FILEXFER_ATTR_SIZE
   	uint32   uid            present only if flag SSH_FILEXFER_ATTR_UIDGID
   	uint32   gid            present only if flag SSH_FILEXFER_ATTR_UIDGID
   	uint32   permissions    present only if flag SSH_FILEXFER_ATTR_PERMISSIONS
   	uint32   atime          present only if flag SSH_FILEXFER_ACMODTIME
   	uint32   mtime          present only if flag SSH_FILEXFER_ACMODTIME
   	uint32   extended_count present only if flag SSH_FILEXFER_ATTR_EXTENDED
   	string   extended_type
   	string   extended_data
   	...      more extended data (extended_type - extended_data pairs),
   		   so that number of pairs equals extended_count

   The `flags' specify which of the fields are present.  Those fields
   for which the corresponding flag is not set are not present (not
   included in the packet).  New flags can only be added by incrementing
   the protocol version number (or by using the extension mechanism
   described below).

   The `size' field specifies the size of the file in bytes.

   The `uid' and `gid' fields contain numeric Unix-like user and group
   identifiers, respectively.

   The `permissions' field contains a bit mask of file permissions as
   defined by posix [1].

   The `atime' and `mtime' contain the access and modification times of
   the files, respectively.  They are represented as seconds from Jan 1,
   1970 in UTC.

   The SSH_FILEXFER_ATTR_EXTENDED flag provides a general extension



Ylonen & Lehtinen         Expires April 1, 2002                 [Page 8]

Internet-Draft         SSH File Transfer Protocol           October 2001


   mechanism for vendor-specific extensions.  If the flag is specified,
   then the `extended_count' field is present.  It specifies the number
   of extended_type-extended_data pairs that follow.  Each of these
   pairs specifies an extended attribute.  For each of the attributes,
   the extended_type field should be a string of the format
   "name@domain", where "domain" is a valid, registered domain name and
   "name" identifies the method.  The IETF may later standardize certain
   names that deviate from this format (e.g., that do not contain the
   "@" sign).  The interpretation of `extended_data' depends on the
   type.  Implementations SHOULD ignore extended data fields that they
   do not understand.

   Additional fields can be added to the attributes by either defining
   additional bits to the flags field to indicate their presence, or by
   defining extended attributes for them.  The extended attributes
   mechanism is recommended for most purposes; additional flags bits
   should only be defined by an IETF standards action that also
   increments the protocol version number.  The use of such new fields
   MUST be negotiated by the version number in the protocol exchange.
   It is a protocol error if a packet with unsupported protocol bits is
   received.

    The flags bits are defined to have the following values:

   	#define SSH_FILEXFER_ATTR_SIZE          0x00000001
   	#define SSH_FILEXFER_ATTR_UIDGID        0x00000002
   	#define SSH_FILEXFER_ATTR_PERMISSIONS   0x00000004
   	#define SSH_FILEXFER_ATTR_ACMODTIME     0x00000008
   	#define SSH_FILEXFER_ATTR_EXTENDED      0x80000000






















Ylonen & Lehtinen         Expires April 1, 2002                 [Page 9]

Internet-Draft         SSH File Transfer Protocol           October 2001


6. Requests From the Client to the Server

   Requests from the client to the server represent the various file
   system operations.  Each request begins with an `id' field, which is
   a 32-bit identifier identifying the request (selected by the client).
   The same identifier will be returned in the response to the request.
   One possible implementation of it is a monotonically increasing
   request sequence number (modulo 2^32).

   Many operations in the protocol operate on open files.  The
   SSH_FXP_OPEN request can return a file handle (which is an opaque
   variable-length string) which may be used to access the file later
   (e.g.  in a read operation).  The client MUST NOT send requests the
   server with bogus or closed handles.  However, the server MUST
   perform adequate checks on the handle in order to avoid security
   risks due to fabricated handles.

   This design allows either stateful and stateless server
   implementation, as well as an implementation which caches state
   between requests but may also flush it.  The contents of the file
   handle string are entirely up to the server and its design.  The
   client should not modify or attempt to interpret the file handle
   strings.

   The file handle strings MUST NOT be longer than 256 bytes.

6.1 Request Synchronization and Reordering

   The protocol and implementations MUST process requests relating to
   the same file in the order in which they are received.  In other
   words, if an application submits multiple requests to the server, the
   results in the responses will be the same as if it had sent the
   requests one at a time and waited for the response in each case.  For
   example, the server may process non-overlapping read/write requests
   to the same file in parallel, but overlapping reads and writes cannot
   be reordered or parallelized.  However, there are no ordering
   restrictions on the server for processing requests from two different
   file transfer connections.  The server may interleave and parallelize
   them at will.

   There are no restrictions on the order in which responses to
   outstanding requests are delivered to the client, except that the
   server must ensure fairness in the sense that processing of no
   request will be indefinitely delayed even if the client is sending
   other requests so that there are multiple outstanding requests all
   the time.





Ylonen & Lehtinen         Expires April 1, 2002                [Page 10]

Internet-Draft         SSH File Transfer Protocol           October 2001


6.2 File Names

   This protocol represents file names as strings.  File names are
   assumed to use the slash ('/') character as a directory separator.

   File names starting with a slash are "absolute", and are relative to
   the root of the file system.  Names starting with any other character
   are relative to the user's default directory (home directory).  Note
   that identifying the user is assumed to take place outside of this
   protocol.

   Servers SHOULD interpret a path name component ".." as referring to
   the parent directory, and "." as referring to the current directory.
   If the server implementation limits access to certain parts of the
   file system, it must be extra careful in parsing file names when
   enforcing such restrictions.  There have been numerous reported
   security bugs where a ".." in a path name has allowed access outside
   the intended area.

   An empty path name is valid, and it refers to the user's default
   directory (usually the user's home directory).

   Otherwise, no syntax is defined for file names by this specification.
   Clients should not make any other assumptions; however, they can
   splice path name components returned by SSH_FXP_READDIR together
   using a slash ('/') as the separator, and that will work as expected.

   It is understood that the lack of well-defined semantics for file
   names may cause interoperability problems between clients and servers
   using radically different operating systems.  However, this approach
   is known to work acceptably with most systems, and alternative
   approaches that e.g.  treat file names as sequences of structured
   components are quite complicated.

6.3 Opening, Creating, and Closing Files

    Files are opened and created using the SSH_FXP_OPEN message, whose
   data part is as follows:

   	uint32        id
   	string        filename
   	uint32        pflags
   	ATTRS         attrs

   The `id' field is the request identifier as for all requests.

   The `filename' field specifies the file name.  See Section ``File
   Names'' for more information.



Ylonen & Lehtinen         Expires April 1, 2002                [Page 11]

Internet-Draft         SSH File Transfer Protocol           October 2001


    The `pflags' field is a bitmask.  The following bits have been
   defined.

   	#define SSH_FXF_READ            0x00000001
   	#define SSH_FXF_WRITE           0x00000002
   	#define SSH_FXF_APPEND          0x00000004
   	#define SSH_FXF_CREAT           0x00000008
   	#define SSH_FXF_TRUNC           0x00000010
   	#define SSH_FXF_EXCL            0x00000020

   These have the following meanings:

   SSH_FXF_READ
      Open the file for reading.

   SSH_FXF_WRITE
      Open the file for writing.  If both this and SSH_FXF_READ are
      specified, the file is opened for both reading and writing.

   SSH_FXF_APPEND
      Force all writes to append data at the end of the file.

   SSH_FXF_CREAT
      If this flag is specified, then a new file will be created if one
      does not already exist (if O_TRUNC is specified, the new file will
      be truncated to zero length if it previously exists).

   SSH_FXF_TRUNC
      Forces an existing file with the same name to be truncated to zero
      length when creating a file by specifying SSH_FXF_CREAT.
      SSH_FXF_CREAT MUST also be specified if this flag is used.

   SSH_FXF_EXCL
      Causes the request to fail if the named file already exists.
      SSH_FXF_CREAT MUST also be specified if this flag is used.

   The `attrs' field specifies the initial attributes for the file.
   Default values will be used for those attributes that are not
   specified.  See Section ``File Attributes'' for more information.

   Regardless the server operating system, the file will always be
   opened in "binary" mode (i.e., no translations between different
   character sets and newline encodings).

   The response to this message will be either SSH_FXP_HANDLE (if the
   operation is successful) or SSH_FXP_STATUS (if the operation fails).





Ylonen & Lehtinen         Expires April 1, 2002                [Page 12]

Internet-Draft         SSH File Transfer Protocol           October 2001


    A file is closed by using the SSH_FXP_CLOSE request.  Its data field
   has the following format:

   	uint32     id
   	string     handle

   where `id' is the request identifier, and `handle' is a handle
   previously returned in the response to SSH_FXP_OPEN or
   SSH_FXP_OPENDIR.  The handle becomes invalid immediately after this
   request has been sent.

   The response to this request will be a SSH_FXP_STATUS message.  One
   should note that on some server platforms even a close can fail.
   This can happen e.g.  if the server operating system caches writes,
   and an error occurs while flushing cached writes during the close.

6.4 Reading and Writing

    Once a file has been opened, it can be read using the SSH_FXP_READ
   message, which has the following format:

   	uint32     id
   	string     handle
   	uint64     offset
   	uint32     len

   where `id' is the request identifier, `handle' is an open file handle
   returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) relative
   to the beginning of the file from where to start reading, and `len'
   is the maximum number of bytes to read.

   In response to this request, the server will read as many bytes as it
   can from the file (up to `len'), and return them in a SSH_FXP_DATA
   message.  If an error occurs or EOF is encountered before reading any
   data, the server will respond with SSH_FXP_STATUS.  For normal disk
   files, it is guaranteed that this will read the specified number of
   bytes, or up to end of file.  For e.g.  device files this may return
   fewer bytes than requested.

    Writing to a file is achieved using the SSH_FXP_WRITE message, which
   has the following format:

   	uint32     id
   	string     handle
   	uint64     offset
   	string     data

   where `id' is a request identifier, `handle' is a file handle



Ylonen & Lehtinen         Expires April 1, 2002                [Page 13]

Internet-Draft         SSH File Transfer Protocol           October 2001


   returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) from the
   beginning of the file where to start writing, and `data' is the data
   to be written.

   The write will extend the file if writing beyond the end of the file.
   It is legal to write way beyond the end of the file; the semantics
   are to write zeroes from the end of the file to the specified offset
   and then the data.  On most operating systems, such writes do not
   allocate disk space but instead leave "holes" in the file.

   The server responds to a write request with a SSH_FXP_STATUS message.

6.5 Removing and Renaming Files

    Files can be removed using the SSH_FXP_REMOVE message.  It has the
   following format:

   	uint32     id
   	string     filename

   where `id' is the request identifier and `filename' is the name of
   the file to be removed.  See Section ``File Names'' for more
   information.  This request cannot be used to remove directories.

   The server will respond to this request with a SSH_FXP_STATUS
   message.

    Files (and directories) can be renamed using the SSH_FXP_RENAME
   message.  Its data is as follows:

   	uint32     id
   	string     oldpath
   	string     newpath

   where `id' is the request identifier, `oldpath' is the name of an
   existing file or directory, and `newpath' is the new name for the
   file or directory.  It is an error if there already exists a file
   with the name specified by newpath.  The server may also fail rename
   requests in other situations, for example if `oldpath' and `newpath'
   point to different file systems on the server.

   The server will respond to this request with a SSH_FXP_STATUS
   message.








Ylonen & Lehtinen         Expires April 1, 2002                [Page 14]

Internet-Draft         SSH File Transfer Protocol           October 2001


6.6 Creating and Deleting Directories

    New directories can be created using the SSH_FXP_MKDIR request.  It
   has the following format:

   	uint32     id
   	string     path
   	ATTRS      attrs

   where `id' is the request identifier, `path' and `attrs' specifies
   the modifications to be made to its attributes.  See Section ``File
   Names'' for more information on file names.  Attributes are discussed
   in more detail in Section ``File Attributes''.  specifies the
   directory to be created.  An error will be returned if a file or
   directory with the specified path already exists.  The server will
   respond to this request with a SSH_FXP_STATUS message.

    Directories can be removed using the SSH_FXP_RMDIR request, which
   has the following format:

   	uint32     id
   	string     path

   where `id' is the request identifier, and `path' specifies the
   directory to be removed.  See Section ``File Names'' for more
   information on file names.  An error will be returned if no directory
   with the specified path exists, or if the specified directory is not
   empty, or if the path specified a file system object other than a
   directory.  The server responds to this request with a SSH_FXP_STATUS
   message.

6.7 Scanning Directories

   The files in a directory can be listed using the SSH_FXP_OPENDIR and
   SSH_FXP_READDIR requests.  Each SSH_FXP_READDIR request returns one
   or more file names with full file attributes for each file.  The
   client should call SSH_FXP_READDIR repeatedly until it has found the
   file it is looking for or until the server responds with a
   SSH_FXP_STATUS message indicating an error (normally SSH_FX_EOF if
   there are no more files in the directory).  The client should then
   close the handle using the SSH_FXP_CLOSE request.










Ylonen & Lehtinen         Expires April 1, 2002                [Page 15]

Internet-Draft         SSH File Transfer Protocol           October 2001


    The SSH_FXP_OPENDIR opens a directory for reading.  It has the
   following format:

   	uint32     id
   	string     path

   where `id' is the request identifier and `path' is the path name of
   the directory to be listed (without any trailing slash).  See Section
   ``File Names'' for more information on file names.  This will return
   an error if the path does not specify a directory or if the directory
   is not readable.  The server will respond to this request with either
   a SSH_FXP_HANDLE or a SSH_FXP_STATUS message.

    Once the directory has been successfully opened, files (and
   directories) contained in it can be listed using SSH_FXP_READDIR
   requests.  These are of the format

   	uint32     id
   	string     handle

   where `id' is the request identifier, and `handle' is a handle
   returned by SSH_FXP_OPENDIR.  (It is a protocol error to attempt to
   use an ordinary file handle returned by SSH_FXP_OPEN.)

   The server responds to this request with either a SSH_FXP_NAME or a
   SSH_FXP_STATUS message.  One or more names may be returned at a time.
   Full status information is returned for each name in order to speed
   up typical directory listings.

   When the client no longer wishes to read more names from the
   directory, it SHOULD call SSH_FXP_CLOSE for the handle.  The handle
   should be closed regardless of whether an error has occurred or not.

6.8 Retrieving File Attributes

   Very often, file attributes are automatically returned by
   SSH_FXP_READDIR.  However, sometimes there is need to specifically
   retrieve the attributes for a named file.  This can be done using the
   SSH_FXP_STAT, SSH_FXP_LSTAT and SSH_FXP_FSTAT requests.

    SSH_FXP_STAT and SSH_FXP_LSTAT only differ in that SSH_FXP_STAT
   follows symbolic links on the server, whereas SSH_FXP_LSTAT does not
   follow symbolic links.  Both have the same format:

   	uint32     id
   	string     path

   where `id' is the request identifier, and `path' specifies the file



Ylonen & Lehtinen         Expires April 1, 2002                [Page 16]

Internet-Draft         SSH File Transfer Protocol           October 2001


   system object for which status is to be returned.  The server
   responds to this request with either SSH_FXP_ATTRS or SSH_FXP_STATUS.

    SSH_FXP_FSTAT differs from the others in that it returns status
   information for an open file (identified by the file handle).  Its
   format is as follows:

   	uint32     id
   	string     handle

   where `id' is the request identifier and `handle' is a file handle
   returned by SSH_FXP_OPEN.  The server responds to this request with
   SSH_FXP_ATTRS or SSH_FXP_STATUS.

6.9 Setting File Attributes

   File attributes may be modified using the SSH_FXP_SETSTAT and
   SSH_FXP_FSETSTAT requests.  These requests are used for operations
   such as changing the ownership, permissions or access times, as well
   as for truncating a file.

    The SSH_FXP_SETSTAT request is of the following format:

   	uint32     id
   	string     path
   	ATTRS      attrs

   where `id' is the request identifier, `path' specifies the file
   system object (e.g.  file or directory) whose attributes are to be
   modified, and `attrs' specifies the modifications to be made to its
   attributes.  Attributes are discussed in more detail in Section
   ``File Attributes''.

   An error will be returned if the specified file system object does
   not exist or the user does not have sufficient rights to modify the
   specified attributes.  The server responds to this request with a
   SSH_FXP_STATUS message.

    The SSH_FXP_FSETSTAT request modifies the attributes of a file which
   is already open.  It has the following format:

   	uint32     id
   	string     handle
   	ATTRS      attrs

   where `id' is the request identifier, `handle' (MUST be returned by
   SSH_FXP_OPEN) identifies the file whose attributes are to be
   modified, and `attrs' specifies the modifications to be made to its



Ylonen & Lehtinen         Expires April 1, 2002                [Page 17]

Internet-Draft         SSH File Transfer Protocol           October 2001


   attributes.  Attributes are discussed in more detail in Section
   ``File Attributes''.  The server will respond to this request with
   SSH_FXP_STATUS.

6.10 Dealing with Symbolic links

    The SSH_FXP_READLINK request may be used to read the target of a
   symbolic link.  It would have a data part as follows:

   	uint32     id
   	string     path

   where `id' is the request identifier and `path' specifies the path
   name of the symlink to be read.

   The server will respond with a SSH_FXP_NAME packet containing only
   one name and a dummy attributes value.  The name in the returned
   packet contains the target of the link.  If an error occurs, the
   server may respond with SSH_FXP_STATUS.

    The SSH_FXP_SYMLINK request will create a symbolic link on the
   server.  It is of the following format

   	uint32     id
   	string     linkpath
   	string     targetpath

   where `id' is the request identifier, `linkpath' specifies the path
   name of the symlink to be created and `targetpath' specifies the
   target of the symlink.  The server shall respond with a
   SSH_FXP_STATUS indicating either success (SSH_FX_OK) or an error
   condition.

6.11 Canonicalizing the Server-Side Path Name

    The SSH_FXP_REALPATH request can be used to have the server
   canonicalize any given path name to an absolute path.  This is useful
   for converting path names containing ".." components or relative
   pathnames without a leading slash into absolute paths.  The format of
   the request is as follows:

   	uint32     id
   	string     path

   where `id' is the request identifier and `path' specifies the path
   name to be canonicalized.  The server will respond with a
   SSH_FXP_NAME packet containing only one name and a dummy attributes
   value.  The name is the returned packet will be in canonical form.



Ylonen & Lehtinen         Expires April 1, 2002                [Page 18]

Internet-Draft         SSH File Transfer Protocol           October 2001


   If an error occurs, the server may also respond with SSH_FXP_STATUS.


















































Ylonen & Lehtinen         Expires April 1, 2002                [Page 19]

Internet-Draft         SSH File Transfer Protocol           October 2001


7. Responses from the Server to the Client

   The server responds to the client using one of a few response
   packets.  All requests can return a SSH_FXP_STATUS response upon
   failure.  When the operation is successful, any of the responses may
   be returned (depending on the operation).  If no data needs to be
   returned to the client, the SSH_FXP_STATUS response with SSH_FX_OK
   status is appropriate.  Otherwise, the SSH_FXP_HANDLE message is used
   to return a file handle (for SSH_FXP_OPEN and SSH_FXP_OPENDIR
   requests), SSH_FXP_DATA is used to return data from SSH_FXP_READ,
   SSH_FXP_NAME is used to return one or more file names from a
   SSH_FXP_READDIR or SSH_FXP_REALPATH request, and SSH_FXP_ATTRS is
   used to return file attributes from SSH_FXP_STAT, SSH_FXP_LSTAT, and
   SSH_FXP_FSTAT requests.

   Exactly one response will be returned for each request.  Each
   response packet contains a request identifier which can be used to
   match each response with the corresponding request.  Note that it is
   legal to have several requests outstanding simultaneously, and the
   server is allowed to send responses to them in a different order from
   the order in which the requests were sent (the result of their
   execution, however, is guaranteed to be as if they had been processed
   one at a time in the order in which the requests were sent).

   Response packets are of the same general format as request packets.
   Each response packet begins with the request identifier.

    The format of the data portion of the SSH_FXP_STATUS response is as
   follows:

   	uint32     id
   	uint32     error/status code
   	string     error message (ISO-10646 UTF-8 [RFC-2279])
   	string     language tag (as defined in [RFC-1766])

   where `id' is the request identifier, and `error/status code'
   indicates the result of the requested operation.  The value SSH_FX_OK
   indicates success, and all other values indicate failure.













Ylonen & Lehtinen         Expires April 1, 2002                [Page 20]

Internet-Draft         SSH File Transfer Protocol           October 2001


    Currently, the following values are defined (other values may be
   defined by future versions of this protocol):

   	#define SSH_FX_OK                            0
   	#define SSH_FX_EOF                           1
   	#define SSH_FX_NO_SUCH_FILE                  2
   	#define SSH_FX_PERMISSION_DENIED             3
   	#define SSH_FX_FAILURE                       4
   	#define SSH_FX_BAD_MESSAGE                   5
   	#define SSH_FX_NO_CONNECTION                 6
   	#define SSH_FX_CONNECTION_LOST               7
   	#define SSH_FX_OP_UNSUPPORTED                8

   SSH_FX_OK
      Indicates successful completion of the operation.

   SSH_FX_EOF
      indicates end-of-file condition; for SSH_FX_READ it means that no
      more data is available in the file, and for SSH_FX_READDIR it
      indicates that no more files are contained in the directory.

   SSH_FX_NO_SUCH_FILE
      is returned when a reference is made to a file which should exist
      but doesn't.

   SSH_FX_PERMISSION_DENIED
      is returned when the authenticated user does not have sufficient
      permissions to perform the operation.

   SSH_FX_FAILURE
      is a generic catch-all error message; it should be returned if an
      error occurs for which there is no more specific error code
      defined.

   SSH_FX_BAD_MESSAGE
      may be returned if a badly formatted packet or protocol
      incompatibility is detected.

   SSH_FX_NO_CONNECTION
      is a pseudo-error which indicates that the client has no
      connection to the server (it can only be generated locally by the
      client, and MUST NOT be returned by servers).

   SSH_FX_CONNECTION_LOST
      is a pseudo-error which indicates that the connection to the
      server has been lost (it can only be generated locally by the
      client, and MUST NOT be returned by servers).




Ylonen & Lehtinen         Expires April 1, 2002                [Page 21]

Internet-Draft         SSH File Transfer Protocol           October 2001


   SSH_FX_OP_UNSUPPORTED
      indicates that an attempt was made to perform an operation which
      is not supported for the server (it may be generated locally by
      the client if e.g.  the version number exchange indicates that a
      required feature is not supported by the server, or it may be
      returned by the server if the server does not implement an
      operation).

   The SSH_FXP_HANDLE response has the following format:

   	uint32     id
   	string     handle

   where `id' is the request identifier, and `handle' is an arbitrary
   string that identifies an open file or directory on the server.  The
   handle is opaque to the client; the client MUST NOT attempt to
   interpret or modify it in any way.  The length of the handle string
   MUST NOT exceed 256 data bytes.

    The SSH_FXP_DATA response has the following format:

   	uint32     id
   	string     data

   where `id' is the request identifier, and `data' is an arbitrary byte
   string containing the requested data.  The data string may be at most
   the number of bytes requested in a SSH_FXP_READ request, but may also
   be shorter if end of file is reached or if the read is from something
   other than a regular file.

    The SSH_FXP_NAME response has the following format:

   	uint32     id
   	uint32     count
   	repeats count times:
   		string     filename
   		string     longname
   		ATTRS      attrs

   where `id' is the request identifier, `count' is the number of names
   returned in this response, and the remaining fields repeat `count'
   times (so that all three fields are first included for the first
   file, then for the second file, etc).  In the repeated part,
   `filename' is a file name being returned (for SSH_FXP_READDIR, it
   will be a relative name within the directory, without any path
   components; for SSH_FXP_REALPATH it will be an absolute path name),
   `longname' is an expanded format for the file name, similar to what
   is returned by "ls -l" on Unix systems, and `attrs' is the attributes



Ylonen & Lehtinen         Expires April 1, 2002                [Page 22]

Internet-Draft         SSH File Transfer Protocol           October 2001


   of the file as described in Section ``File Attributes''.

   The format of the `longname' field is unspecified by this protocol.
   It MUST be suitable for use in the output of a directory listing
   command (in fact, the recommended operation for a directory listing
   command is to simply display this data).  However, clients SHOULD NOT
   attempt to parse the longname field for file attributes; they SHOULD
   use the attrs field instead.

    The recommended format for the longname field is as follows:

   	-rwxr-xr-x   1 mjos     staff      348911 Mar 25 14:29 t-filexfer
   	1234567890 123 12345678 12345678 12345678 123456789012

   Here, the first line is sample output, and the second field indicates
   widths of the various fields.  Fields are separated by spaces.  The
   first field lists file permissions for user, group, and others; the
   second field is link count; the third field is the name of the user
   who owns the file; the fourth field is the name of the group that
   owns the file; the fifth field is the size of the file in bytes; the
   sixth field (which actually may contain spaces, but is fixed to 12
   characters) is the file modification time, and the seventh field is
   the file name.  Each field is specified to be a minimum of certain
   number of character positions (indicated by the second line above),
   but may also be longer if the data does not fit in the specified
   length.

    The SSH_FXP_ATTRS response has the following format:

   	uint32     id
   	ATTRS      attrs

   where `id' is the request identifier, and `attrs' is the returned
   file attributes as described in Section ``File Attributes''.

















Ylonen & Lehtinen         Expires April 1, 2002                [Page 23]

Internet-Draft         SSH File Transfer Protocol           October 2001


8. Vendor-Specific Extensions

    The SSH_FXP_EXTENDED request provides a generic extension mechanism
   for adding vendor-specific commands.  The request has the following
   format:

   	uint32     id
   	string     extended-request
   	... any request-specific data ...

   where `id' is the request identifier, and `extended-request' is a
   string of the format "name@domain", where domain is an internet
   domain name of the vendor defining the request.  The rest of the
   request is completely vendor-specific, and servers should only
   attempt to interpret it if they recognize the `extended-request'
   name.

   The server may respond to such requests using any of the response
   packets defined in Section ``Responses from the Server to the
   Client''.  Additionally, the server may also respond with a
   SSH_FXP_EXTENDED_REPLY packet, as defined below.  If the server does
   not recognize the `extended-request' name, then the server MUST
   respond with SSH_FXP_STATUS with error/status set to
   SSH_FX_OP_UNSUPPORTED.

    The SSH_FXP_EXTENDED_REPLY packet can be used to carry arbitrary
   extension-specific data from the server to the client.  It is of the
   following format:

   	uint32     id
   	... any request-specific data ...




















Ylonen & Lehtinen         Expires April 1, 2002                [Page 24]

Internet-Draft         SSH File Transfer Protocol           October 2001


9. Security Considerations

   This protocol assumes that it is run over a secure channel and that
   the endpoints of the channel have been authenticated.  Thus, this
   protocol assumes that it is externally protected from network-level
   attacks.

   This protocol provides file system access to arbitrary files on the
   server (only constrained by the server implementation).  It is the
   responsibility of the server implementation to enforce any access
   controls that may be required to limit the access allowed for any
   particular user (the user being authenticated externally to this
   protocol, typically using the SSH User Authentication Protocol [6].

   Care must be taken in the server implementation to check the validity
   of received file handle strings.  The server should not rely on them
   directly; it MUST check the validity of each handle before relying on
   it.

































Ylonen & Lehtinen         Expires April 1, 2002                [Page 25]

Internet-Draft         SSH File Transfer Protocol           October 2001


10. Changes from previous protocol versions

   The SSH File Transfer Protocol has changed over time, before it's
   standardization.  The following is a description of the incompatible
   changes between different versions.

10.1 Changes between versions 3 and 2

   o  The SSH_FXP_READLINK and SSH_FXP_SYMLINK messages were added.

   o  The SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY messages were
      added.

   o  The SSH_FXP_STATUS message was changed to include fields `error
      message' and `language tag'.


10.2 Changes between versions 2 and 1

   o  The SSH_FXP_RENAME message was added.


10.3 Changes between versions 1 and 0

   o  Implementation changes, no actual protocol changes.


























Ylonen & Lehtinen         Expires April 1, 2002                [Page 26]

Internet-Draft         SSH File Transfer Protocol           October 2001


11. Trademark Issues

   "ssh" is a registered trademark of SSH Communications Security Corp
   in the United States and/or other countries.















































Ylonen & Lehtinen         Expires April 1, 2002                [Page 27]

Internet-Draft         SSH File Transfer Protocol           October 2001


References

   [1]  Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and
        P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January
        1999.

   [2]  Institute of Electrical and Electronics Engineers, "Information
        Technology - Portable Operating System Interface (POSIX) - Part
        1: System Application Program Interface (API) [C Language]",
        IEEE Standard 1003.2, 1996.

   [3]  Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.
        Lehtinen, "SSH Protocol Architecture", draft-ietf-secsh-
        architecture-09 (work in progress), July 2001.

   [4]  Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.
        Lehtinen, "SSH Protocol Transport Protocol", draft-ietf-secsh-
        architecture-09 (work in progress), July 2001.

   [5]  Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.
        Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-11
        (work in progress), July 2001.

   [6]  Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S.
        Lehtinen, "SSH Authentication Protocol", draft-ietf-secsh-
        userauth-11 (work in progress), July 2001.


Authors' Addresses

   Tatu Ylonen
   SSH Communications Security Corp
   Fredrikinkatu 42
   HELSINKI  FIN-00100
   Finland

   EMail: [email protected]


   Sami Lehtinen
   SSH Communications Security Corp
   Fredrikinkatu 42
   HELSINKI  FIN-00100
   Finland

   EMail: [email protected]





Ylonen & Lehtinen         Expires April 1, 2002                [Page 28]

Internet-Draft         SSH File Transfer Protocol           October 2001


Full Copyright Statement

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















Ylonen & Lehtinen         Expires April 1, 2002                [Page 29]