RFC 1415
FTP-FTAM Gateway Specification
Pages: 58
Historic
Historic
Part 3 of 3 – Pages 38 to 58
8.2. FTAM-Initiated Gateway Service The protocol mapping between FTP and FTAM may be one-to-zero (i.e., not mappable), one-to-one, or one-to-many. The general steps taken by the FTP-FTAM gateway to provide the FTAM- Initiated service are: 1. Accept an FTAM Initiator request at the FTAM Responder side of the gateway. 2. Map the request to the (set of) corresponding FTP Client
function(s).
3. Acting as an FTP Client, send the FTP Client function(s) to
the FTP Server.
4. Accept information returned to the FTP Client side of the
gateway. This information originated at the FTP Server.
5. Map this returned information to a form understood by the
FTAM Responder side of the gateway.
6. Send this returned information from the FTAM Responder side
of the gateway to the FTAM Initiator.
For each FTAM protocol function, the FTP protocol functions required
to map it are identified:
FTAM FTP
-----------------------------------------------------------------
F-BEGIN-GROUP none
F-CANCEL ABOR
F-CHANGE-ATTRIBUTE RNFR, RNTO
F-CHECK none
F-CLOSE none
F-CREATE STOR
F-DATA ALLO, STOR or RETR or APPE
F-DATA-END none
F-DELETE DELE
F-DESELECT none
F-END-GROUP STAT
F-ERASE DELE
F-INITIALIZE ACCT, PASS, USER
F-LOCATE none
F-OPEN MODE, STRU, TYPE
F-READ MODE, NLST, RETR, TYPE
F-READ-ATTRIBUTE LIST
F-RECOVER REST
F-RESTART ABOR, REST
F-SELECT LIST
F-TERMINATE QUIT
F-TRANSFER none
F-P-ABORT QUIT
F-U-ABORT QUIT
F-WRITE APPE or STOR, NOOP
The remainder of this section presents detailed mapping procedures
for each of the FTAM protocol functions. Where appropriate, each
FTAM service primitive is followed by those parameters that are
relevant to the mapping. Gateway support for these mappings is
required.
8.2.1. F-BEGIN-GROUP REQ
1. Send F-BEGIN-GROUP RESP PDU to FTAM Initiator signifying
that processes are available to handle concatenated
requests.
8.2.2. F-CANCEL REQ
1. Close FTP data connection.
2. Send ABOR to FTP Server.
3. Translate FTP Server reply code to equivalent FTAM
Responder action and diagnostic parameters and send
parameters to FTAM Initiator via F-CANCEL RESP PDU.
4. Translate FTAM Initiator action and diagnostic parameters
to equivalent FTP reply codes and send reply codes to FTP
Server.
Note:
a. F-U-ABORT REQ is a viable alternative to F-CANCEL REQ.
b. Note that since ABOR is not implemented by all FTP Servers,
the remote file may be corrupted, though accessible.
8.2.3. F-CHANGE-ATTRIBUTE REQ
1. Get original filename from <Filename> parameter and send it
with an RNFR to the FTP Server.
2. Get new filename from <Filename> parameter and send it with
an RNTO to the FTP Server.
3. Translate FTP Server reply code to equivalent FTAM
Responder action and diagnostic parameters and send
parameters to FTAM Initiator via F-CHANGE-ATTRIBUTE RESP
PDU.
4. Translate FTAM Initiator action and diagnostic parameters
to equivalent FTP reply codes and send reply codes to FTP
Server.
Note:
a. Allow for processing an arbitrary number attributes at one
time.
b. Allow for responses of "Attribute currently unavailable for
change" and "Attribute not currently supported".
c. At a minimum, support the <Filename>, <Permitted Actions>,
and <Contents Type> parameters.
8.2.4. F-CHECK REQ
1. Send an F-CHECK RESP PDU to the FTAM Initiator.
8.2.5. F-CLOSE REQ
1. Send F-CLOSE RESP PDU , with <Action Result> parameter
value of "Success", to FTAM Initiator.
Note:
a. If an error had occurred during transfer, it would have
been noted before the F-CLOSE REQ.
8.2.6. F-CREATE REQ
1. Send STOR and zero data bytes to FTP Server.
2. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator.
3. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.2.7. F-DATA PDU 1. If necessary, send ALLO command to FTP Server. 2. Depending on whether reading or writing, send STOR, RETR, or APPE command to FTP Server. 3. Translate FTP Server reply code to equivalent FTAM Responder <Action Result> and <Diagnostic> parameters and send parameters to FTAM Initiator. 4. Translate FTAM Initiator <Action Result> and <Diagnostic> parameters to equivalent FTP reply codes and send reply codes to FTP Server. Note: a. The use of an FTP command may be unnecessary. Sending the data on the data connection may be adequate. 8.2.8. F-DATA-END REQ 1. Close the data connection. 2. Save mandatory Diagnostic parameter for later use. 3. Translate FTP Server reply code to equivalent FTAM Responder <Action Result> and <Diagnostic> parameters and send parameters to FTAM Initiator. 4. Translate FTAM Initiator <Action Result> and <Diagnostic> parameters to equivalent FTP reply codes and send reply codes to FTP Server. 8.2.9. F-DELETE REQ 1. Send DELE to FTP server. 2. Translate FTP Server reply code to equivalent FTAM Responder <Action Result> and <Diagnostic> parameters and send parameters to FTAM Initiator via F-DELETE RESP PDU. 3. Translate FTAM Initiator <Action Result> and <Diagnostic> parameters to equivalent FTP reply codes and send reply codes to FTP Server. 8.2.10. F-DESELECT REQ 1. Return F-DESELECT RESP PDU, with <Action Result> parameter value of "Success", to FTAM Initiator. 8.2.11. F-END-GROUP REQ 1. Send STAT command sequence to FTP Server. 2. Translate FTP Server reply code to equivalent FTAM Responder <Action Result> and <Diagnostic> parameters and send parameters to FTAM Initiator via F-END
GROUP RESP.
3. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.2.12. F-ERASE REQ
1. Send DELE to FTP Server.
2. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator via F-ERASE RESP PDU.
3. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.2.13. F-INITIALIZE REQ
1. Establish initial area for activity attributes.
2. Save <Responding Presentation Address>, <Initiator
Identity>, and <Filestore Password> parameter values
received from FTAM Initiator.
3. If the destination address was specified in the
Distinguished Name (or User Friendly Name) used to attach
to the gateway, save it as the ultimate destination
address.
4. If the ultimate destination address is not yet known, look
at the "@host" portion of the <Initiator Identity>
parameter for the ultimate destination parameter.
5. If the ultimate destination address is still not known,
check if it is available in the <Responding Presentation
Address> parameter.
6. Get userid from <Initiator Identity> and send it with USER
command to FTP Server.
7. Get password from <Filestore Password> and send it with
PASS command to FTP Server.
8. If necessary, send ACCT command to FTP Server.
9. Negotiate acceptance of mandatory functional units, service
classes, service types, presentation contexts, and
attribute groups.
10. Accept context management functional unit passed by
Presentation service provider.
11. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator via F-INIT RESP PDU.
12. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
Note:
a. Multiple mechanisms are available for specifying the
destination address: 1) Distinguished Name, or User
Friendly Name, used in connecting to the gateway (see
section 4, Use of Gateway Services); 2) user@host format;
and 3) Inclusion as <Responding Presentation Address>
parameter value.
8.2.14. F-LOCATE REQ
Note:
a. Not supported since FTAM-1 and FTAM-3 don't support this
primitive.
8.2.15. F-OPEN REQ
1. Get <Contents Type> and <Processing Mode> parameter values
from FTAM Initiator.
2. Send TYPE command to FTP Server.
3. Send MODE command to FTP Server.
4. Send STRU command to FTP Server.
5. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic>
parameters and send parameters to FTAM Initiator via F-OPEN
RESP PDU.
6. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
Note:
a. Establishes definite value for presentation context name
parameter for this data transfer.
b. Assumes that the <Requested Access> parameter is permitted.
8.2.16. F-READ REQ
1. If requested file type and file mode are different than
current settings, send TYPE and MODE to FTP Server.
2. If <Contents Type> is FTAM-1 or FTAM-3, then send RETR to
FTP Server.
3. If <Contents Type> is "NBS-9", then send NLST to FTP
Server.
4. If reply code from FTP Server is 1xx, open FTP data
connection and loop until End-of-File is read on FTP data
connection. Inside loop, read block from FTP data
connection, format FTAM DATA PDU, and send FTAM PDU to FTAM
Initiator. At End-of-File on FTP data connection, send
F-DATA-END and return.
5. If reply code from FTP Server is not 1xx, send F-CANCEL REQ
to FTAM Initiator.
6. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator via F-READ RESP PDU.
7. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
Note:
a. To send NLST response, TYPE must be ASCII.
8.2.17. F-READ-ATTRIBUTE REQ
1. Send LIST to FTP Server.
2. Translate returned information into the <Filename>,
<Contents Type>, and <Permitted Actions> parameter values
and return them to the FTAM Initiator.
3. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator via F-READ-ATTRIBUTE RESP
PDU.
4. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.2.18. F-RECOVER REQ
1. Send REST command to FTP Server.
2. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator.
3. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
Note:
a. Regime recovery is only possible if the <Recovery
Functional Unit> parameter was negotiated previously by an
F-INITIALIZE.
8.2.19. F-RESTART REQ
1. To interrupt any bulk data transfer in progress, send ABOR
to FTP Server.
2. To negotiate the point at which data transfer is to be
restarted, get <Checkpoint Identifier> parameter from FTAM
Initiator and send it with REST to FTP Server.
3. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator via F-RESTART RESP PDU.
4. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.2.20. F-SELECT REQ
1. Get <Filename> parameter and send with LIST command to FTP
Server to determine whether or not the file exists.
2. If file exists, compare the POSIX file access rights with
the <Requested Access> parameter sent by the FTAM
Initiator. If the access rights match, return <Action
Result> parameter value of "Success", otherwise return
<Action Result> parameter value of "Failure".
3. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator via F-SELECT RESP PDU.
4. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
Note:
a. The specified file is binary/text file if one record is
received or is a directory file if multiple records are
received.
8.2.21. F-TERMINATE REQ
1. Send QUIT to FTP Server.
2. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator via F-TERMINATE RESP PDU.
3. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.2.22. F-TRANSFER-END
1. Get <Action Result> parameter value from last F-DATA-END
and return it to FTAM Initiator as <Action Result>
parameter of this F-TRANSFER-END.
8.2.23. F-P-ABORT REQ
1. Send QUIT to FTP Server.
2. Return <Action Result> parameter value of "Permanent Error"
to FTAM Initiator.
3. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator.
4. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.2.24. F-U-ABORT REQ
1. Send QUIT to FTP Server.
2. Return <Action Result> parameter value of "Permanent Error"
to FTAM Initiator.
3. Translate FTP Server reply code to equivalent FTAM
Responder <Action Result> and <Diagnostic> parameters and
send parameters to FTAM Initiator.
4. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
8.3. F-WRITE REQ
1. Save bulk transfer specification parameter from PDU.
2. Send NOOP to FTP Server to receive status information.
3. If the <Bulk Data Transfer Specification, FADU Operation>
parameter has a value of "File Extend", then send an APPE
to the FTP Server, otherwise send a STOR to the FTP Server.
4. If reply code from FTP Server is 200, then accept FTP data
connection; otherwise send F-CANCEL REQ to FTAM Initiator.
5. Translate FTP Server reply code to equivalent FTAM Responder
<Action Result> and <Diagnostic> parameters and send
parameters to FTAM Initiator.
6. Translate FTAM Initiator <Action Result> and <Diagnostic>
parameters to equivalent FTP reply codes and send reply
codes to FTP Server.
9. Mapping between FTP Reply Codes and FTAM Parameters
The focus of the protocol function and representation mappings,
presented in the previous sections, is on non-error encumbered
processing. Though appropriate responses are designated in many
cases, it is intended that a more thorough use of responses will be
incorporated into gateway implementations.
The purpose of this section is to provide a set of mappings between
FTAM responses (<Action Result> and <Diagnostic>) and FTP responses
(reply codes).
The <Action Result> parameter of the FTAM File Service primitives conveys information which summarizes that available in the <Diagnostic> parameter. The value is never less than the most severe diagnostic value. The valid values of this parameter are "Success", "Transient Error", and "Permanent Error". The FTP response text should be supplied in the <Further Details> field of the <Diagnostics> sequence in the FTAM response and abort messages. An FTAM <Action Result> "Success" may be accompanied by a <Diagnostic> with value of "Informative Error Type". These "Success" diagnostic messages are associated with error type 0 in the table below (and in [ISO8571-3]). Error type 1 indicates a transient error, while type 2 indicates a permanent error. An FTP reply consists of a three digit number followed by some text. The number is defined as a 3-digit code, each digit of which has a special significance. The first digit conveys approximately the same information as the FTAM <Action Result> parameter; i.e., positive, transient negative, or permanent negative. The FTP specification document [RFC959] explicitly states that the list of reply codes should not be expanded beyond that which is presented in [RFC959]. This requirement is adhered to in the mappings presented in this document. 9.1. FTP Reply Codes to FTAM Parameters This section presents the set of mappings between FTP reply codes and their equivalent FTAM action and diagnostic parameters. Gateway support for these mappings is recommended, but not required. The following abbreviations are used for FTAM action parameter values: trans = transient error perman = permanent error FTP Reply |FTAM Diagnostic | | Code Text |Result Type Id ---------------------------------------------+------------------ 110 Restart marker reply |success 0 0 120 Service ready in nnn minutes |success 0 0 125 Data connection open, transfer | starting |success 0 0 150 File status okay; about to open | data connection |success 0 0 200 Command okay |success 0 0 202 Command not implemented; |
superfluous |success 0 0
211 System status, or system help |
reply |success 0 0
212 Directory status |success 0 0
213 File status |success 0 0
214 Help message |success 0 0
215 NAME system type |success 0 0
220 Service ready for new user |success 0 0
221 Service closing control connection |success 0 0
225 Data connection; no transfer in |
progress |success 0 0
226 Closing data connection |success 0 0
227 Entering passive mode (h1,h2,..) |success 0 0
230 User logged in, proceed |success 0 0
250 Requested file action okay, |
completed |success 0 0
257 "PATHNAME" created |success 0 0
331 User name okay, need password |success 0 0
332 Need account for logon |success 0 0
350 Requested file action pending |
further information |success 0 0
421 Service not available, closing |
control connection |trans 1 1
425 Can't open data connection |trans 1 3
426 Connection closed, transfer |
aborted |trans 1 1014
450 Requested file action not taken, |
file unavailable (e.g., file busy) |trans 1 5041
451 Requested file action aborted, |
local error in processing |trans 1 5028
452 Requested action not taken, |
insufficient storage space |trans 1 9
500 Syntax error, command unrecognized |perman 2 5015
501 Syntax error in parameters or |
arguments |perman 2 4004
502 Command not implemented |perman 2 5016
503 Bad sequence of commands |perman 2 1015
504 Command not implemented for that |
parameter |perman 2 4003
530 Not logged in |perman 2 2020
532 Need account for storing files |perman 2 2008
550 Requested action not taken; file |
unavailable (e.g., file not found, |
no access) |perman 2 3013
551 Requested action aborted, page |
type |perman 2 5002
552 Requested file action aborted, |
exceeded storage allocation |perman 2 9
553 Requested file action not taken, |
file name not allowed |perman 2 3024
9.2. FTAM Parameters to FTP Reply Codes
This section presents the set of mappings between FTAM diagnostic
parameters and their equivalent FTP reply codes. Gateway support for
these mappings is recommended, but not required. As previously
mentioned, type 0 is an informative error type that may be returned
with a "Success" action result, type 1 is a transient error type, and
type 2 is a permanent error type.
FTAM Diagnostic |FTP Reply Code
|
Type Id Reason |
--------------------------------------------------+--------
|
1,2 0 No reason | 421
0 1 Responder error | 211
1,2 1 Responder error | 421
1,2 2 System shutdown | 421
0 3 FTAM mgmt problem, unspecific | 211
1,2 3 FTAM mgmt problem, unspecific | 425
0 4 FTAM mgmt, bad account | 221
2 4 FTAM mgmt, bad account | 532
0 5 FTAM mgmt, security not passed | 211
2 5 FTAM mgmt, security not passed | 530
0 6 Delay may be encountered | 211
0 7 Initiator error, unspecific | 211
1,2 7 Initiator error, unspecific | 421
0 8 Subsequent error | 211
1,2 8 Subsequent error | 421
0 9 Temporal insufficiency of resources| 211
1,2 9 Temporal insufficiency of resources| 452
1,2 10 Access req. violates VFS security | 550
1,2 11 Access req. violates local security| 550
2 1000 Conflicting parameter values | 504
2 1001 Unsupported parameter values | 504
2 1002 Mandatory parameter not set | 504
2 1003 Unsupported parameter | 504
2 1004 Duplicated parameter | 504
2 1005 Illegal parameter type | 504
2 1006 Unsupported parameter types | 504
2 1007 FTAM protocol err., unspecific | 426
2 1008 FTAM protocol err., procedure err | 426
2 1009 FTAM protocol err., funct. unit err| 426
2 1010 FTAM protocol err., corruption err.| 426
2 1011 Lower layer failure | 426
1,2 1012 Lower layer addressing error | 426
1,2 1013 Timeout | 426
1,2 1014 System shutdown | 426
2 1015 Illegal grouping sequence | 503
2 1016 Grouping threshold violation | 503
2 1017 Inconsistent PDU request | 503
2 2000 Association with user not allowed | 532
2 2002 Unsupported service class | 504
0 2003 Unsupported functional unit | 211
2 2003 Unsupported functional unit | 502
0 2004 Attribute group error, unspecific | 211
1,2 2004 Attribute group error, unspecific | 504
2 2005 Attribute group not supported | 504
0 2006 Attribute group not allowed | 211
2 2006 Attribute group not allowed | 504
0 2007 Bad account | 211
2 2007 Bad account | 532
0 2008 Association management, unspecific | 211
1,2 2008 Association management, unspecific | 532
2 2009 Association management, bad address| 532
1,2 2010 Association management, bad account| 532
0 2011 Checkpoint window error, too large | 211
2 2011 Checkpoint window error, too large | 426
0 2012 Checkpoint window error, too small | 211
2 2012 Checkpoint window error, too small | 426
0 2013 Checkpoint window error, unsupp. | 211
2 2013 Checkpoint window error, unsupp. | 504
0 2014 Communications QoS not supported | 211
1,2 2014 Communications QoS not supported | 504
2 2015 Initiator identity unacceptable | 532
0 2016 Context management refused | 211
0 2017 Rollback not available | 211
0 2018 Contents type list cut by |
responder | 211
0 2019 Contents type list by |
Presentation Service | 211
2 2020 Invalid filestore password | 530
2 2021 Incompatible service classes | 530
1,2 3000 Filename not found | 550
1,2 3001 Selection attributes not matched | 550
2 3002 Initial attributes not possible | 550
2 3003 Bad attribute name | 550
1,2 3004 Non-existent file | 550
1,2 3005 File already exists | 553
1,2 3006 File cannot be created | 553
1,2 3007 File cannot be deleted | 553
0 3008 Concurrency control not available | 211
2 3008 Concurrency control not available | 503
0 3009 Concurrency control not supported | 211
2 3009 Concurrency control not supported | 502
0 3010 Concurrency control not possible | 211
2 3010 Concurrency control not possible | 503
0 3011 More restrictive lock | 211
1 3011 More restrictive lock | 450
1,2 3012 File busy | 450
1,2 3013 File not available | 450
0 3014 Access control not available | 211
1,2 3014 Access control not available | 503
0 3015 Access control not supported | 211
1,2 3015 Access control not supported | 502
0 3016 Access control inconsistent | 211
1,2 3016 Access control inconsistent | 503
0 3017 Filename truncated | 211
0 3018 Initial attributes altered | 211
1,2 3019 Bad account | 532
0 3020 Override selected existing file | 211
0 3021 Override deleted and recreated | 211
0 3022 Create override deleted and |
recreate file with new attributes | 211
1,2 3023 Create override, not possible | 553
1,2 3024 Ambiguous file specification | 553
2 3025 Invalid create password | 550
2 3026 Invalid delete password on override| 550
2 3027 Bad attribute value | 550
2 3028 Requested access violation | 550
2 3029 Functional unit not available for | 550
requested access |
0 3030 File created but not selected | 211
1 3030 Invalid create password | 550
0 4000 Attribute non-existent | 211
1,2 4000 Attribute non-existent | 501
1,2 4001 Attribute cannot be read | 504
1,2 4002 Attribute cannot be changed | 504
1,2 4003 Attribute not supported | 504
2 4004 Bad attribute name | 501
2 4005 Bad attribute value | 501
0 4006 Attribute partially supported | 211
0 4007 Additional set attribute value |
not distinct | 211
1,2 5000 Bad FADU, unspecific | 550
2 5001 Bad FADU, size error | 501
2 5002 Bad FADU, type error | 551
2 5003 Bad FADU, poorly specified | 501
2 5004 Bad FADU, bad location | 550
0 5005 FADU does not exist | 550
1 5005 FADU does not exist | 550
0 5006 FADU not available, unspecific | 550
1,2 5006 FADU not available, unspecific | 550
1,2 5007 FADU not available for reading | 550
1,2 5008 FADU not available for writing | 550
1,2 5009 FADU not available for location | 550
1,2 5010 FADU not available for erasure | 550
1,2 5011 FADU cannot be inserted | 550
1,2 5012 FADU cannot be replaced | 550
0 5013 FADU cannot be located | 550
1,2 5013 FADU cannot be located | 550
2 5014 Bad data element type | 550
1,2 5015 Operation not available | 500
1,2 5016 Operation not supported | 502
0 5017 Operation inconsistent | 211
2 5017 Operation inconsistent | 503
0 5018 Concurrency control not available | 211
1,2 5018 Concurrency control not available | 503
0 5019 Concurrency control not supported | 211
2 5019 Concurrency control not supported | 502
0 5020 Concurrency control inconsistent | 211
2 5020 Concurrency control inconsistent | 503
0 5021 Processing mode not available | 211
1,2 5021 Processing mode not available | 503
0 5022 Processing mode not supported | 211
2 5022 Processing mode not supported | 504
0 5023 Processing mode inconsistent | 211
2 5023 Processing mode inconsistent | 503
0 5024 Access context not available | 211
2 5024 Access context not available | 503
0 5025 Access context not supported | 211
2 5025 Access context not supported | 504
1,2 5026 Bad write, unspecific | 550
1,2 5027 Bad read, unspecific | 550
0 5028 Local failure, unspecific | 211
1,2 5028 Local failure, unspecific | 451
0 5029 Local failure, filespace exhausted | 211
1,2 5029 Local failure, filespace exhausted | 552
0 5030 Local failure, data corrupted | 211
1,2 5030 Local failure, data corrupted | 451
0 5031 Local failure, data corrupted | 211
1,2 5031 Local failure, data corrupted | 451
2 5032 Future file size exceeded | 451
0 5034 Future file size increased | 211
0 5035 Functional unit invalid in |
processing mode | 211
2 5035 Functional unit invalid in |
processing mode | 503
0 5036 Contents type inconsistent | 211
2 5036 Contents type inconsistent | 503
0 5037 Contents type simplified | 211
0 5038 Duplicate FADU name | 211
1,2 5039 Damage to select/open regime | 553
1,2 5040 FADU locking not available on file | 450
1,2 5041 FADU locked by another user | 450
9.3. Future Mapping Problem
At some point in the future, the FTAM <Responding Presentation
Address> parameter may be used for purposes other than the current
use of passing the final destination address in the FTAM-Initiated
gateway service [NIST86]. If this happens, the destination address
will have to be passed in another location, such as in the "@host"
portion of the <Initiator Identity>. Currently, the FTP-FTAM gateway
specification permits either mechanism for storage of the ultimate
destination address.
9.4. Error Handling
The minimal acceptable solution for FTAM-Initiated service errors is
to map FTP failures to FTAM "Unrecoverable error" and return the FTP
diagnostic string in the FTAM <Further Details> field. Similarly for
FTP-Initiated service errors, the minimal acceptable solution is to
return reply code 221, "Service closing control connection, Logged
out if appropriate". While this minimal solution is acceptable, the
recommended approach for Gateway developers is to implement the
mappings presented in Section 9.1, FTP Reply Codes to FTAM
Parameters, and Section 9.2, FTAM Parameters to FTP Reply Codes.
10. Implementation and Configuration Guidelines
The intent of this specification is to specify the required
characteristics and functions of an FTP-FTAM gateway. The specific
approach taken to realize these specifications in an operational
gateway are left to the discretion of the implementor. We do take
the liberty, however, of suggesting several ideas concerning the
configuration and implementation of such gateways.
10.1. Robustness
The gateway should be robust enough to handle situations where a
subset of the FTP and/or FTAM protocols are implemented on a host.
The gateway should support multiple concurrent FTP and FTAM
connections.
These are requirements for gateway implementations. 10.2. Well-Known TCP/IP Port It is recommended that the FTP-Initiated gateway process listen on TCP/IP port 21, the well-known port for FTP listener processes. As the gateway computer is primarily intended to provide gateway services, use of this port will alleviate the need for gateway users to specify the desired port when they connect to the gateway. The standard FTP server listener process can then be moved to another port that is known to those users (e.g., System Administrators) requiring FTP-to-FTP access to the gateway computer. 10.3. Gateway Listener Processes To simplify the administrative overhead on the gateway computer system, it is recommended that the FTP-Initiated service and FTAM- Initiated gateway listener processes be merged into a single executable module. This single daemon will act as the one and only gateway listener processes. As connections were established with hosts, other processes would be created. 10.4. Implementation Testing To assist in the development and evaluation of FTP-FTAM gateway prototypes, NIST has developed a test system to evaluate a gateway's conformance to the protocol standards [NIST88]. 10.5. POSIX File Naming and Organization The OSI profiles do not define a standard manner for an FTAM Responder to return file names. To avoid unnecessary complexity, proprietary file systems are not addressed in these mappings. Gateway support for POSIX file naming and organization conventions is required; i.e., files are assumed to be organized in a hierarchical structure in which all of the non- terminal nodes are directories and all of the terminal nodes are any other type of file. 11. Security Considerations The gateway system may place the burden of authentication on the destination system. However, the gateway must accommodate the passing through of all authentication parameters. The authentication parameters of each protocol are applied at the destination and no additional parameters are needed for authentication at the gateway. As such, no gateway password file is required to support gateway
functions. It is anticipated that the requirement for a strong authentication mechanism will soon replace the most currently used, userid and password mechanism. The U.S. National Security Agency (NSA) has already prototyped and has plans field a Message Secure Protocol (MSP) as part of the Defense Message System (DMS) Program which will soon become the Department of Defense (DoD) mandatory messaging system. MSP utilizes a public key encryption-like mechanism which will be used to authenticate users and allow signed operations. The current philosophy is to use this same mechanism for all authentication and access control situations, such as logging onto remote hosts or gateways. Detailed specifications for Pre-MSP, used in the unclassified though sensitive arena, are scheduled to be published in the first quarter of 1993. The requirement for gateways to process PMSP and MSP strong authentication mechanisms will be part of all future DoD procurements. 12. References [ISO8571-1] Information processing systems - Open Systems Interconnection - File Transfer, Access and Management, Part 1: General Introduction, International Standards Organization for Standards, First Edition, October 1988. [ISO8571-2] Information processing systems - Open Systems Interconnection - File Transfer, Access and Management, Part 2: Virtual Filestore Definition, International Standards Organization for Standards, First Edition, October 1988. [ISO8571-3] Information processing systems - Open Systems Interconnection - File Transfer, Access and Management, Part 3: File Service Definition, International Standards Organization for Standards, First Edition, October 1988. [ISO8571-4] Information processing systems - Open Systems Interconnection - File Transfer, Access and Management, Part 4: File Protocol Specification, International Standards Organization for Standards, First Edition, October 1988. [ISO8571-5] Information processing systems - Open Systems Interconnection - File Transfer, Access and Management, Part 5: Protocol Implementation Conformance Statement, International Standards Organization for Standards, First Edition.
[KILLE92] Hardcastle-Kille, S., "Using the OSI Directory to achieve User Friendly Naming", OSI-DS 24 (v1.1), October 1992. [MITRE87] Scott, J., "An FTP/FTAM Application Bridge, An FTAM/FTAM (MTR-87W00186)", The MITRE Corporation, July 1987. [NETWRX90a] Mindel, J., "Gateway Technical Specification" Open Networks, Inc. (formerly NetWorks One), 28 February 1990. [NETWRX90b] Mindel, J., "FTP Gateway User's Guide", Open Networks, Inc. (formerly NetWorks One), 28 February 1990. [NIST86] Wallace, M, et. al., "A Gateway Architecture Between FTP and FTAM (ICST/SNA86-6)", National Institute of Standards and Technology, U.S. Department of Commerce, July 1986. [NIST88] A Test System for Implementations of FTAM/FTP Gateways: Final Report Part 1, National Institute of Standards and Technology, U.S. Chamber of Commerce, October 1988. [NIST91] CSL Bulletin: File Transfer, Access, and Management, National Institute of Standards and Technology, U.S. Chamber of Commerce, July 1991. [NIST92] Stable Implementation Agreements for Open Systems Interconnection Protocols: Part 9 - FTAM Phase 2, Output from the March 1992 Open Systems Environment Implementors' Workshop (OIW), March 1992. [RFC959] Postel, J., and J. Reynolds, "File Transfer Protocol (FTP), STD 9, RFC 959, USC/Information Sciences Institute, October 1985. [RFC1101] Mockapetris, P., "DNS Encoding of Network Names and other Types", RFC 1101, USC/Information Sciences Institute, April 1989. [RFC1279] Hardcastle-Kille, S., "X.500 and Domain", RFC 1279, University College London, November 1991. [ROSE90] Rose, M., "The Open Book: A Practical Perspective on OSI", Prentice-Hall Inc., 1990.
13. Authors' Addresses Joshua L. Mindel Open Networks, Inc. 11490 Commerce Park Dr., Suite 205 Reston, Virginia 22091 USA Phone: (703) 648-0013 Email: mindel@netwrx1.nw1.com Robert L. Slaski Open Networks, Inc. 11490 Commerce Park Dr., Suite 205 Reston, Virginia 22091 USA Phone: (703) 648-0013 Email: slaski@netwrx1.nw1.com