Network Working Group T. Murphy, Jr.

Network Working Group T. Murphy, Jr.
Request for Comments: 2877 P. Rieth
Category: Informational J. Stevens
Updates: 1205 IBM Corporation
July 2000

5250 Telnet Enhancements

Status of this Memo

This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2000). All Rights Reserved.

Abstract

This memo describes the interface to the IBM 5250 Telnet server that
allows client Telnet to request a Telnet terminal or printer session
using a specific device name. If a requested device name is not
available, a method to retry the request using a new device name is
described. Methods to request specific Telnet session settings and
auto-signon function are also described.

By allowing a Telnet client to select the device name, the 5250
Telnet server opens the door for applications to set and/or extract
useful information about the Telnet client. Some possibilities are
1) selecting a customized device name associated with a particular
user profile name for National Language Support or subsystem routing,
2) connecting PC and network printers as clients and 3) auto-signon
using clear-text or DES-encrypted password exchange.

Applications may need to use system API's on the AS/400 in order to
extract Telnet session settings from the device name description.
Refer to the Retrieve Device Description (QDCRDEVD) API described in
the AS/400 System API book [3] on how to extract information using
the DEVD0600 and DEVD1100 templates.

This memo describes how the IBM 5250 Telnet server supports Work
Station Function (WSF) printers using 5250 Display Station Pass-
Through. A response code is returned by the Telnet server to
indicate success or failure of the WSF printer session.

Murphy, et al. Informational [Page 1]

RFC 2877 5250 Telnet Enhancements July 2000

Table of Contents

1. Enhancing Telnet Negotiations...................... 3
2. Standard Telnet Option Negotiation................. 3
3. Enhanced Telnet Option Negotiation................. 4
4. Enhanced Display Emulation Support................. 7
5. Enhanced Display Auto-Signon and Password
Encryption......................................... 8
5.1 Password Substitutes Processing.............. 12
5.2 Handling passwords of length 9 and 10........ 14
5.3 Example Password Substitute Calculation...... 15
6. Device Name Collision Processing................... 15
7. Enhanced Printer Emulation Support................. 16
8. Telnet Printer Terminal Types...................... 18
9. Telnet Printer Startup Response Record for Printer
Emulators.......................................... 20
9.1 Example of a Success Response Record......... 20
9.2 Example of an Error Response Record.......... 21
9.3 Response Codes............................... 22
10. Printer Steady-State Pass-Through Interface........ 23
10.1 Example of a Print Record.................... 25
10.2 Example of a Print Complete Record........... 27
10.3 Example of a Null Print Record............... 27
11. End-to-End Print Example........................... 28
12. Authors' Note...................................... 33
13. References......................................... 33
14. Security Considerations............................ 35
15. Authors' Addresses................................. 35
16. Relation to Other RFC's............................ 35
17. Full Copyright Statement........................... 36

LIST OF FIGURES

Figure 1. Example of a success status response
record....................................... 20
Figure 2. Example of an error response record.......... 21
Figure 3. Layout of the printer pass-through
header....................................... 23
Figure 4. Server sending client data with a print
record....................................... 26
Figure 5. Client sending server a print complete
record....................................... 27
Figure 6. Server sending client a null print
record....................................... 28

Murphy, et al. Informational [Page 2]

RFC 2877 5250 Telnet Enhancements July 2000

1. Enhancing Telnet Negotiations

The 5250 Telnet server enables clients to negotiate both terminal and
printer device names through Telnet Environment Options Negotiations,
defined in the Standards Track RFC 1572 [13].

The purpose of RFC 1572 is to exchange environment information using
a set of standard or custom variables. By using a combination of
both standard VAR's and custom USERVAR's, the 5250 Telnet server
allows client Telnet to request a pre-defined specific device by
name.

If no pre-defined device exists then the device will be created, with
client Telnet having the option to negotiate device attributes, such
as the code page, character set, keyboard type, etc.

Since printers can now be negotiated as a device name, new terminal
types have been defined to request printers. For example, you can
now negotiate "IBM-3812-1" and "IBM-5553-B01" as valid TERMINAL-TYPE
options [11].

Finally, the 5250 Telnet server will allow exchange of user profile
and password information, where the password may be in either clear-
text or encrypted form. If a valid combination of profile and
password is received, then the client is allowed to bypass the sign-
on panel. The setting of the QRMTSIGN system value must be either
*VERIFY or *SAMEPRF for the bypass of the sign-on panel to succeed.

2. Standard Telnet Option Negotiation

Telnet server option negotiation typically begins with the issuance,
by the server, of an invitation to engage in terminal type
negotiation with the Telnet client (DO TERMINAL-TYPE) [11]. The
client and server then enter into a series of sub-negotiations to
determine the level of terminal support that will be used. After the
terminal type is agreed upon, the client and server will normally
negotiate a required set of additional options (EOR [12], BINARY
[10], SGA [15]) that are required to support "transparent mode" or
full screen 5250/3270 block mode support. As soon as the required
options have been negotiated, the server will suspend further
negotiations, and begin with initializing the actual virtual device
on the AS/400. A typical exchange might start like the following:

Murphy, et al. Informational [Page 3]

RFC 2877 5250 Telnet Enhancements July 2000

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
IAC DO TERMINAL-TYPE -->
<-- IAC WILL TERMINAL-TYPE
IAC SB TERMINAL-TYPE SEND
IAC SE -->
IAC SB TERMINAL-TYPE IS
<-- IBM-5555-C01 IAC SE
IAC DO EOR -->
<-- IAC WILL EOR
<-- IAC DO EOR
IAC WILL EOR -->
.
.
(other negotiations) .

Actual bytes transmitted in the above example are shown in hex below.

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
FF FD 18 -->
<-- FF FB 18
FF FA 18 01 FF F0 -->
FF FA 18 00 49 42 4D 2D
35 35 35 35 2D 43 30 31
<-- FF F0
FF FD 19 -->
<-- FF FB 19
<-- FF FD 19
FF FB 19 -->
.
.
(other negotiations) .

Some negotiations are symmetrical between client and server and some
are negotiated in one direction only. Also, it is permissible and
common practice to bundle more than one response or request, or
combine a request with a response, so the actual exchange may look
different in practice to what is shown above.

3. Enhanced Telnet Option Negotiation

In order to accommodate the new environment option negotiations, the
server will bundle an environment option invitation along with the
standard terminal type invitation request to the client.

Murphy, et al. Informational [Page 4]

RFC 2877 5250 Telnet Enhancements July 2000

A client should either send a negative acknowledgment (WONT NEW-
ENVIRON), or at some point after completing terminal-type
negotiations, but before completing the full set of negotiations
required for 5250 transparent mode, engage in environment option
sub-negotiation with the server. A maximum of 1024 bytes of
environment strings may be sent to the server. A recommended
sequence might look like the following:

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
IAC DO NEW-ENVIRON
IAC DO TERMINAL-TYPE -->
(2 requests bundled)
<-- IAC WILL NEW-ENVIRON
IAC SB NEW-ENVIRON SEND
VAR IAC SE -->
IAC SB NEW-ENVIRON IS
VAR "USER" VALUE "JONES"
USERVAR "DEVNAME"
VALUE "MYDEVICE07"
<-- IAC SE
<-- IAC WILL TERMINAL-TYPE
(do the terminal type
sequence first)
IAC SB TERMINAL-TYPE SEND
IAC SE -->
IAC SB TERMINAL-TYPE IS
<-- IBM-5555-C01 IAC SE
(terminal type negotiations
completed)
IAC DO EOR -->
(server will continue
with normal transparent
mode negotiations)
<-- IAC WILL EOR
.
.
(other negotiations) .

Actual bytes transmitted in the above example are shown in hex below.

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
FF FD 27
FF FD 18 -->
(2 requests bundled)
<-- FF FB 27
FF FA 27 01 00 FF F0 -->

Murphy, et al. Informational [Page 5]

RFC 2877 5250 Telnet Enhancements July 2000

FF FA 27 00 00 55 53 45
52 01 4A 4F 4E 45 53 03
44 45 56 4E 41 4D 45 01
4D 59 44 45 56 49 43 45
<-- 30 37 FF F0
<-- FF FB 18
(do the terminal type
sequence first)
FF FA 18 01 FF F0 -->
FF FA 18 00 49 42 4D 2D
35 35 35 35 2D 43 30 31
<-- FF F0
FF FD 19 -->
(server will continue
with normal transparent
mode negotiations)
<-- FF FB 19
.
.
(other negotiations) .

RFC 1572 defines 6 standard VAR's: USER, JOB, ACCT, PRINTER,
SYSTEMTYPE, and DISPLAY. The USER standard VAR will hold the value
of the AS/400 user profile name to be used in auto-signon requests.
The Telnet server will make no direct use of the additional 5 VAR's,
nor are any of them required to be sent. All standard VAR's and
their values that are received by the Telnet server will be placed in
a buffer, along with any USERVAR's received (described below), and
made available to a registered initialization exit program to be used
for any purpose desired.

There are some reasons you may want to send NEW-ENVIRON negotiations
prior to TERMINAL-TYPE negotiations. With AS/400 TELNET server,
several virtual device modes can be negotiated: 1) VTxxx device 2)
3270 device 3) 5250 device (includes Network Station). The virtual
device mode selected depends on the TERMINAL-TYPE negotiated plus any
other TELNET option negotiations necessary to support those modes.
The AS/400 TELNET server will create the desired virtual device at
the first opportunity it thinks it has all the requested attributes
needed to create the device. This can be as early as completion of
the TERMINAL-TYPE negotiations.

For the case of Transparent mode (5250 device), then the moment
TERMINAL-TYPE, BINARY, and EOR options are negotiated the TELNET
server will go create the virtual device. Receiving any NEW-ENVIRON
negotiations after these option negotiations are complete will result
in the NEW-ENVIRON negotiations having no effect on device
attributes, as the virtual device will have already been created.

Murphy, et al. Informational [Page 6]

RFC 2877 5250 Telnet Enhancements July 2000

So, for Transparent mode, NEW-ENVIRON negotiations are effectively
closed once EOR is negotiated, since EOR is generally the last option
done.

For other devices modes (such as VTxxx or 3270), you cannot be sure
when the AS/400 TELNET server thinks it has all the attributes to
create the device. Recall that NEW-ENVIRON negotiations are
optional, and therefore the AS/400 TELNET server need not wait for
any NEW-ENVIRON options prior to creating the virtual device. It is
in the clients best interest to send NEW-ENVIRON negotiations as soon
as possible, preferably before TERMINAL-TYPE is negotiated. That
way, the client can be sure the requested attributes were received
before the virtual device is created.

4. Enhanced Display Emulation Support

RFC 1572 style USERVAR variables have been defined to allow a
compliant Telnet client more control over the Telnet server virtual
device on the AS/400. These USERVAR's allow the client Telnet to
create or select a previously created virtual device. If the virtual
device does not exist and must be created, then the USERVAR variables
are used to create and initialize the device attributes. If the
virtual device already exists, the device attributes are modified.

The USERVAR's defined to accomplish this are:

USERVAR VALUE EXAMPLE DESCRIPTION
-------- ---------------- ---------------- -------------------
DEVNAME us-ascii char(x) MYDEVICE07 Display device name
KBDTYPE us-ascii char(3) USB Keyboard type
CODEPAGE us-ascii char(y) 437 Code page
CHARSET us-ascii char(y) 1212 Character set

x - up to a maximum of 10 characters
y - up to a maximum of 5 characters

For a description of the KBDTYPE, CODEPAGE and CHARSET parameters and
their permissible values, refer to Chapter 8 in the Communications
Configuration Reference [5] and also to Appendix C in National
Language Support [16].

The CODEPAGE and CHARSET USERVAR's must be associated with a KBDTYPE
USERVAR. If either CODEPAGE or CHARSET are sent without KBDTYPE,
they will default to system values. A default value for KBDTYPE can
be sent to force CODEPAGE and CHARSET values to be used.

Murphy, et al. Informational [Page 7]

RFC 2877 5250 Telnet Enhancements July 2000

AS/400 system objects such as device names, user profiles, clear-text
passwords, programs, libraries, etc. are required to be specified in
English Upper Case (EUC). This includes:

Any letter (A-Z), any number (0-9), special characters (# $ _ @)

Therefore, where us-ascii is specified for VAR or USERVAR values, it
is recommended that upper-cased ASCII values be sent, which will be
converted to EBCDIC by the Telnet server.

A special case occurs for encrypted passwords (described in the next
section), where both the initial password and user profile used to
build the encrypted password must be EBCDIC English Upper Case, in
order to be properly authenticated by the Telnet server.

5. Enhanced Display Auto-Signon and Password Encryption

Several 5250 Telnet server specific USERVAR's will be defined. One
will carry a random seed to be used in Data Encryption Standard (DES)
password encryption, and another will carry the encrypted copy of the
password. This would use the same 7-step DES-based password
substitution scheme as APPC and Client Access. For a description of
DES encryption, refer to Federal Information Processing Standards
Publications (FIPS) 46-2 [17] and 81 [18], which can be found at the
Federal Information Processing Standards Publications link:

http://www.itl.nist.gov/div897/pubs/by-num.htm

For a description of the 7-step password substitution scheme, refer
to these IBM Customer Support FTP Server links:

ftp://ftp.networking.ibm.com/pub/standards/ciw/sig/sec/pwsubciw.ps
ftp://ftp.networking.ibm.com/pub/standards/ciw/sig/sec/pwsubciw.ps.Z
ftp://ftp.networking.ibm.com/pub/standards/ciw/sig/sec/pwsubciw.zip

If encrypted password exchange is not required, clear-text password
exchange is permitted using the same USERVAR's defined for
encryption. For this case, the random client seed should be set to
either an empty value (RFC 1572 preferred method) or to hexadecimal
zeros to indicate the password is not encrypted, but is clear-text.

It should be noted that security of clear-text password exchange
cannot be guaranteed unless the network is physically protected or a
trusted network (such as an intranet). If your network is vulnerable
to IP address spoofing or directly connected to the Internet, you
should engage in encrypted password exchange to validate a clients
identity.

Murphy, et al. Informational [Page 8]

RFC 2877 5250 Telnet Enhancements July 2000

Additional VAR's and USERVAR's have also been defined to allow an
auto-signon user greater control over their startup environment,
similar to what is supported using the Open Virtual Terminal
(QTVOPNVT) API [3].

The standard VAR's supported to accomplish this are:

VAR VALUE EXAMPLE DESCRIPTION
-------- ---------------- ---------------- -------------------
USER us-ascii char(x) USERXYZ User profile name

x - up to a maximum of 10 characters

The custom USERVAR's defined to accomplish this are:

USERVAR VALUE EXAMPLE DESCRIPTION
-------- ---------------- ---------------- -------------------
IBMRSEED binary(8) 8-byte hex field Random client seed
IBMSUBSPW binary(10) 10-byte hex field Substitute password
IBMCURLIB us-ascii char(x) QGPL Current library
IBMIMENU us-ascii char(x) MAIN Initial menu
IBMPROGRAM us-ascii char(x) QCMD Program to call

x - up to a maximum of 10 characters

In order to communicate the server random seed value to the client,
the server will request a USERVAR name made up of a fixed part (the 8
characters "IBMRSEED" immediately followed by an 8-byte hexadecimal
variable part, which is the server random seed. The client generates
its own 8-byte random seed value, and uses both seeds to encrypt the
password. Both the encrypted password and the client random seed
value are then sent to the server for authentication. RFC 1572 rules
will need to be adhered to when transmitting the client random seed
and substituted password values to the server. Specifically, since a
typical environment string is a variable length hexadecimal field,
the hexadecimal fields are required to be escaped and/or byte stuffed
according to the RFC 854 [8], where any single byte could be mis-
construed as a Telnet IAC or other Telnet option negotiation control
character. The client must escape and/or byte stuff any bytes which
could be seen as a RFC 1572 [13] option, specifically VAR, VALUE, ESC
and USERVAR.

Murphy, et al. Informational [Page 9]

RFC 2877 5250 Telnet Enhancements July 2000

The following illustrates the encrypted case:

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------------
IAC DO NEW-ENVIRON -->
<-- IAC WILL NEW-ENVIRON
IAC SB NEW-ENVIRON SEND
USERVAR "IBMRSEEDxxxxxxxx"
USERVAR "IBMSUBSPW"
VAR USERVAR IAC SE -->
IAC SB NEW-ENVIRON IS
VAR "USER" VALUE "DUMMYUSR"
USERVAR "IBMRSEED" VALUE "yyyyyyyy"
USERVAR "IBMSUBSPW" VALUE "zzzzzzzz"
<-- IAC SE
.
.
(other negotiations) .

In this example, "xxxxxxxx" is an 8-byte hexadecimal random server
seed, "yyyyyyyy" is an 8-byte hexadecimal random client seed and
"zzzzzzzz" is an 8-byte hexadecimal encrypted password. If the
password is not valid, then the sign-on panel is displayed. If the
password is expired, then the Change Password panel is displayed.

Actual bytes transmitted in the above example are shown in hex below,
where the server seed is "7D3E488F18080404", the client seed is
"4E4142334E414233" and the encrypted password is "DFB0402F22ABA3BA".
The user profile used to generate the encrypted password is
"44554D4D59555352" (DUMMYUSR), with a clear-text password of
"44554D4D595057" (DUMMYPW).

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
FF FD 27 -->
<-- FF FB 27
FF FA 27 01 03 49 42 4D
52 53 45 45 44 7D 3E 48
8F 18 08 04 04 03 49 42
4D 53 55 42 53 50 57 03
00 FF F0 -->
FF FA 27 00 00 55 53 45
52 01 44 55 4D 4D 59 55
53 52 03 49 42 4D 52 53
45 45 44 01 4E 41 42 33
4E 41 42 33 03 49 42 4D

Murphy, et al. Informational [Page 10]

RFC 2877 5250 Telnet Enhancements July 2000

53 55 42 53 50 57 01 DF
B0 40 2F 22 AB A3 BA FF
<-- F0

The following illustrates the clear-text case:

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
IAC DO NEW-ENVIRON -->
<-- IAC WILL NEW-ENVIRON
IAC SB NEW-ENVIRON SEND
USERVAR "IBMRSEEDxxxxxxxx"
USERVAR "IBMSUBSPW"
VAR USERVAR IAC SE -->
IAC SB NEW-ENVIRON IS
VAR "USER" VALUE "DUMMYUSR"
USERVAR "IBMRSEED" VALUE
USERVAR "IBMSUBSPW" VALUE "yyyyyyyy"
<-- IAC SE
.
.
(other negotiations) .

In this example, "xxxxxxxx" is an 8-byte hexadecimal random server
seed, "yyyyyyyyyy" is a 10-byte us-ascii client clear-text password.
If the password has expired, then the sign-on panel is displayed.

Actual bytes transmitted in the above example are shown in hex below,
where the server seed is "7D3E488F18080404", the client seed is empty
and the clear-text password is "44554D4D595057" (DUMMYPW). The user
profile used is "44554D4D59555352" (DUMMYUSR).

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
FF FD 27 -->
<-- FF FB 27
FF FA 27 01 03 49 42 4D
52 53 45 45 44 7D 3E 48
8F 18 08 04 04 03 49 42
4D 53 55 42 53 50 57 03
00 FF F0 -->
FF FA 27 00 00 55 53 45
52 01 44 55 4D 4D 59 55
53 52 03 49 42 4D 52 53
45 45 44 01 03 49 42 4D
53 55 42 53 50 57 01 44
<-- 55 4D 4D 59 50 57 FF F0

Murphy, et al. Informational [Page 11]

RFC 2877 5250 Telnet Enhancements July 2000

5.1 Password Substitutes Processing

Both APPC and Client Access use well-known DES encryption algorithms
to create encrypted passwords. A Network Station or Enhanced Client
can generate compatible encrypted passwords if they follow these
steps, details of which can be found in the Federal Information
Processing Standards 46-2 [17].

1. Padded_PW = Left justified user password padded to the right with
'40'X to 8 bytes.

The users password must be left justified in an 8 byte variable
and padded to the right with '40'X up to an 8 byte length. If the
users password is 8 bytes in length, no padding would occur. For
computing password substitutes for passwords of length 9 and 10
see section "Handling passwords of length 9 and 10" below.
Passwords less than 1 byte or greater than 10 bytes in length are
not valid. Please note, if password is not in EBCDIC, it must be
converted to EBCDIC uppercase.

2. XOR_PW = Padded_PW xor '5555555555555555'X

The padded password is Exclusive OR'ed with 8 bytes of '55'X.

3. SHIFT_RESULT = XOR_PW << 1

The entire 8 byte result is shifted 1 bit to the left; the
leftmost bit value is discarded, and the rightmost bit value is
cleared to 0.

4. PW_TOKEN = DES_ECB_mode(SHIFT_RESULT, /* key */
userID_in_EBCDIC_uppercase /* data */ )

This shifted result is used as key to the Data Encryption Standard
(Federal Information Processing Standards 46-2 [17]) to encipher
the user identifier. When the user identifier is less than 8
bytes, it is left justified in an 8 byte variable and padded to
the right with '40'X. When the user identifier is 9 or 10 bytes,
it is first padded to the right with '40'X to a length of 10
bytes. Then bytes 9 and 10 are "folded" into bytes 1-8 using the
following algorithm:

Bit 0 is the high-order bit (i.e. has value of '80'X).

Byte 1, bits 0 and 1 are replaced with byte 1, bits 0 and 1
Exclusive OR'ed with byte 9, bits 0 and 1.
Byte 2, bits 0 and 1 are replaced with byte 2, bits 0 and 1
Exclusive OR'ed with byte 9, bits 2 and 3.

Murphy, et al. Informational [Page 12]

RFC 2877 5250 Telnet Enhancements July 2000

Byte 3, bits 0 and 1 are replaced with byte 3, bits 0 and 1
Exclusive OR'ed with byte 9, bits 4 and 5.
Byte 4, bits 0 and 1 are replaced with byte 4, bits 0 and 1
Exclusive OR'ed with byte 9, bits 6 and 7.
Byte 5, bits 0 and 1 are replaced with byte 5, bits 0 and 1
Exclusive OR'ed with byte 10, bits 0 and 1.
Byte 6, bits 0 and 1 are replaced with byte 6, bits 0 and 1
Exclusive OR'ed with byte 10, bits 2 and 3.
Byte 7, bits 0 and 1 are replaced with byte 7, bits 0 and 1
Exclusive OR'ed with byte 10, bits 4 and 5.
Byte 8, bits 0 and 1 are replaced with byte 8, bits 0 and 1
Exclusive OR'ed with byte 10, bits 6 and 7.

User identifier greater than 10 bytes or less than 1 byte are not
the result of this encryption id known as PW_TOKEN in the paper.

5. Increment PWSEQs and store it.

Each LU must maintain a pair of sequence numbers for ATTACHs sent
and received on each session. Each time an ATTACH is generated,
(and password substitutes are in use on the session) the sending
sequence number, PWSEQs, is incremented and saved for the next
time. Both values are set to zero at BIND time. So the first use
of PWSEQs has the value of 1, and increases by one with each use.
A new field is added to the ATTACH to carry this sequence number.
However, in certain error conditions, it is possible for the
sending side to increment the sequence number and the receiver may
not increment it. When the sender sends a subsequent ATTACH, the
receiver will detect a missing sequence. This is allowed.
However the sequence number received must always be larger than
the previous one, even if some are missing.

The maximum number of consecutive missing sequence numbers allowed
is 16. If this is exceeded, the session is unbound with a
protocol violation.

Note: The sequence number must be incremented for every ATTACH
sent. However, the sequence number field is only required to be
included in the FMH5 if a password substitute is sent (byte 4, bit
3 on).

6. RDrSEQ = RDr + PWSEQs /* RDr is server seed. */

The current value of PWSEQs is added to RDr, the random value
received from the partner LU on this session, yielding RDrSEQ,
essentially a predictably modified value of the random value
received from the partner LU at BIND time.

Murphy, et al. Informational [Page 13]

RFC 2877 5250 Telnet Enhancements July 2000

7. PW_SUB = DES_CBC_mode(PW_TOKEN, /* key */
(RDrSEQ, /* 8 bytes */
RDs, /* 8 bytes */
ID xor RDrSEQ, /* 16 bytes */
PWSEQs, /* 8 bytes */
) /* data */
)

The PW_TOKEN is used as a key to the DES function to generate
a 8 bytes value for the following string of inputs. The DES
CBC mode Initialization Vector (IV) used is 8 bytes of '00'X.

RDrSEQ: the random data value received from the partner LU
plus the sequence number.

RDs: the random data value sent to the partner LU on BIND
for this session.

A 16 byte value created by:

- padding the user identifier with '40'X to a
length of 16 bytes.

- Exclusive OR the two 8 byte halves of the padded
user identifier with the RDrSEQ value.

Note: User ID must first be converted to EBCDIC
upper case.

PWSEQs: the sequence number.

This is similar to the process used on LU-LU verification as
described in the Enhanced LU-LU Bind Security. The resulting
enciphered random data is the 'password substitute'.

5.2 Handling passwords of length 9 and 10

1. Generate PW_TOKENa by using characters 1 to 8 of the password and
steps 1-4 from the previous section.

2. Generate PW_TOKENb by using characters 9 and 10 and steps 1-4 from
the previous section. In this case Padded_PW from step 1 will be
characters 9 and 10 padded to the right with '40'X, for a total
length of 8.

3. PW_TOKEN = PW_TOKENa xor PW_TOKENb

Murphy, et al. Informational [Page 14]

RFC 2877 5250 Telnet Enhancements July 2000

4. Now compute PW_SUB by performing steps 5-7 from the previous
section.

5.3 Example Password Substitute Calculation

ID: USER123
Password: ABCDEFG
Server seed: '7D4C2319F28004B2'X
Client seed: '08BEF662D851F4B1'X
PWSEQs: 1 (PWSEQs is a sequence number needed in the
7-step encryption, and it is always one)

Encrypted Password should be : '5A58BD50E4DD9B5F'X

6. Device Name Collision Processing

Device name collision occurs when a Telnet client sends the Telnet
server a virtual device name that it wants to use, but that device is
already in use on the server. When this occurs, the Telnet server
sends a request to the client asking it to try another device name.
The environment option negotiation uses the USERVAR name of DEVNAME
to communicate the virtual device name. The following shows how the
Telnet server will request the Telnet client to send a different
DEVNAME when device name collision occurs.

AS/400 Telnet server Enhanced Telnet client
-------------------------- -------------------------
IAC SB NEW-ENVIRON SEND
VAR USERVAR IAC SE -->

Server requests all environment variables be sent.

IAC SB NEW-ENVIRON IS USERVAR
"DEVNAME" VALUE "MYDEVICE1"
USERVAR "xxxxx" VALUE "xxx"
...
<-- IAC SE

Client sends all environment variables, including DEVNAME. Server
tries to select device MYDEVICE1. If the device is already in use,
server requests DEVNAME be sent again.

IAC SB NEW-ENVIRON SEND
USERVAR "DEVNAME" IAC SE -->

Murphy, et al. Informational [Page 15]

RFC 2877 5250 Telnet Enhancements July 2000

Server sends a request for a single environment variable: DEVNAME

IAC SB NEW-ENVIRON IS USERVAR
<-- "DEVNAME" VALUE "MYDEVICE2" IAC SE

Client sends one environment variable, calculating a new value of
MYDEVICE2. If MYDEVICE2 is different from the last request, then
server tries to select device MYDEVICE2, else server disconnects
client. If MYDEVICE2 is also in use, server will send DEVNAME
request again, and keep doing so until it receives a device that is
not in use, or the same device name twice in row.

7. Enhanced Printer Emulation Support

RFC 1572 style USERVAR variables have been defined to allow a
compliant Telnet client more control over the Telnet server virtual
device on the AS/400. These USERVAR's allow the client Telnet to
select a previously created virtual device or auto-create a new
virtual device with requested attributes.

This makes the enhancements available to any Telnet client that
chonoses to support the new negotiations.

The USERVAR's defined to accomplish this are:

USERVAR VALUE EXAMPLE DESCRIPTION
------------- ---------------- ---------------- -------------------
DEVNAME us-ascii char(x) PRINTER1 Printer device name
IBMIGCFEAT us-ascii char(6) 2424J0 IGC feature (DBCS)
IBMMSGQNAME us-ascii char(x) QSYSOPR *MSGQ name
IBMMSGQLIB us-ascii char(x) QSYS *MSGQ library
IBMFONT us-ascii char(x) 12 Font
IBMFORMFEED us-ascii char(1) C | U | A Formfeed
IBMTRANSFORM us-ascii char(1) 1 | 0 Transform
IBMMFRTYPMDL us-ascii char(x) *IBM42023 Mfg. type and model
IBMPPRSRC1 binary(1) 1-byte hex field Paper source 1
IBMPPRSRC2 binary(1) 1-byte hex field Paper source 2
IBMENVELOPE binary(1) 1-byte hex field Envelope hopper
IBMASCII899 us-ascii char(1) 1 | 0 ASCII 899 support
IBMWSCSTNAME us-ascii char(x) *NONE WSCST name
IBMWSCSTLIB us-ascii char(x) *LIBL WSCST library

x - up to a maximum of 10 characters

The "IBM" prefix on the USERVAR's denotes AS/400 specific attributes.

The DEVNAME USERVAR is used both for displays and printers. The
IBMFONT and IBMASCII899 are used only for SBCS environments.

Murphy, et al. Informational [Page 16]

RFC 2877 5250 Telnet Enhancements July 2000

For a description of most of these parameters (drop the "IBM" from
the USERVAR) and their permissible values, refer to Chapter 8 in the
Communications Configuration Reference [5].

The IBMIGCFEAT supports the following variable DBCS language
identifiers in position 5 (positions 1-4 must be '2424', position 6
must be '0'):

'J' = Japanese 'K' = Korean
'C' = Traditional Chinese 'S' = Simplified Chinese

The IBMTRANSFORM and IBMASCII899 values correspond to:

'1' = Yes '2' = No

The IBMFORMFEED values correspond to:

'C' = Continuous 'U' = Cut 'A' = Autocut

The IBMPPRSRC1, IBMPPRSRC2 and IBMENVELOPE custom USERVAR's do not
map directly to their descriptions in Chapter 8 in the Communications
Configuration Reference [5]. To map these, use the index listed
here:

IBMPPRSRC1 HEX IBMPPRSRC2 HEX IBMENVELOPE HEX
---------- ----- ---------- ----- ----------- -----
*NONE 'FF'X *NONE 'FF'X *NONE 'FF'X
*MFRTYPMDL '00'X *MFRTYPMDL '00'X *MFRTYPMDL '00'X
*LETTER '01'X *LETTER '01'X *B5 '06'X
*LEGAL '02'X *LEGAL '02'X *MONARCH '09'X
*EXECUTIVE '03'X *EXECUTIVE '03'X *NUMBER9 '0A'X
*A4 '04'X *A4 '04'X *NUMBER10 '0B'X
*A5 '05'X *A5 '05'X *C5 '0C'X
*B5 '06'X *B5 '06'X *DL '0D'X
*CONT80 '07'X *CONT80 '07'X
*CONT132 '08'X *CONT132 '08'X
*A3 '0E'X *A3 '0E'X
*B4 '0F'X *B4 '0F'X
*LEDGER '10'X *LEDGER '10'X

Note 1: For IBMPPRSRC2, *CONT80 and *CONT132 support starts at V3R7.

Note 2: For IBMPPRSRC1 and IBMPPRSRC2, *A3, *B4 and *LEDGER support
starts at V3R7.

Murphy, et al. Informational [Page 17]

RFC 2877 5250 Telnet Enhancements July 2000

8. Telnet Printer Terminal Types

New Telnet options are defined for the printer pass-through mode of
operation. To enable printer pass-through mode, both the client and
server must agree to at least support the Transmit-Binary, End-Of-
Record, and Terminal-Type Telnet options. The following are new
terminal types for printers:

TERMINAL-TYPE DESCRIPTION
------------- -------------------
IBM-5553-B01 Double-Byte printer
IBM-3812-1 Single-Byte printer

Specific characteristics of the IBM-5553-B01 or IBM-3812-1 printers
are specified through the USERVAR IBMMFRTYPMDL, which specifies the
manufacturer type and model.

An example of a typical negotiation process to establish printer
pass-through mode of operation is shown below. In this example, the
server initiates the negotiation by sending the DO TERMINAL-TYPE
request.

For DBCS environments, if IBMTRANSFORM is set to 1 (use Host Print
Transform), then the virtual device created is 3812, not 5553.
Therefore, IBM-3812-1 should be negotiated for TERMINAL-TYPE, and not
IBM-5553-B01.

AS/400 Telnet server Enhanced Telnet client
-------------------------- --------------------------
IAC DO NEW-ENVIRON -->
<-- IAC WILL NEW-ENVIRON
IAC SB NEW-ENVIRON SEND
VAR USERVAR IAC SE -->
IAC SB NEW-ENVIRON IS
USERVAR "DEVNAME" VALUE "PCPRINTER"
USERVAR "IBMMSGQNAME" VALUE "QSYSOPR"
USERVAR "IBMMSGQLIB" VALUE "*LIBL"
USERVAR "IBMTRANSFORM" VALUE "0"
USERVAR "IBMFONT" VALUE "12"
USERVAR "IBMFORMFEED" VALUE "C"
USERVAR "IBMPPRSRC1" VALUE ESC '01'X
USERVAR "IBMPPRSRC2" VALUE '04'X
USERVAR "IBMENVELOPE" VALUE IAC 'FF'X
<-- IAC SE
IAC DO TERMINAL-TYPE -->
<-- IAC WILL TERMINAL-TYPE
IAC SB TERMINAL-TYPE SEND
IAC SE -->

Murphy, et al. Informational [Page 18]

RFC 2877 5250 Telnet Enhancements July 2000

IAC SB TERMINAL-TYPE IS IBM-3812-1
<-- IAC SE
IAC DO BINARY -->
<-- IAC WILL BINARY
IAC DO EOR -->
<-- IAC WILL EOR

Some points about the above example. The IBMPPRSRC1 value requires
escaping the value using ESC according to RFC 1572 [13]. The
IBMPPRSRC2 does not require an ESC character since '04'X has no
conflict with RFC 1572 options. Finally, to send 'FF'X for the
IBMENVELOPE value, escape the 'FF'X value by using another 'FF'X
(called "doubling"), so as not to have the value interpreted as a
Telnet character per RFC 854 [8].

Actual bytes transmitted in the above example are shown in hex below.

AS/400 Telnet server Enhanced Telnet client
-------------------------- --------------------------
FF FD 27 -->
<-- FF FB 27
FF FA 27 01 00 03 FF F0 -->
FF FA 27 00 03 44 45 56
4E 41 4D 45 01 50 43 50
52 49 4E 54 45 52 03 49
42 4D 4D 53 47 51 4E 41
4D 45 01 51 53 59 53 4F
50 52 03 49 42 4D 4D 53
47 51 4C 49 42 01 2A 4C
49 42 4C 03 49 42 4D 54
52 41 4E 53 46 4F 52 4D
01 30 03 49 42 4D 46 4F
4E 54 01 31 32 03 49 42
4D 46 4F 52 4D 46 45 45
44 01 43 03 49 42 4D 50
50 52 53 52 43 31 01 02
01 03 49 42 4D 50 50 52
53 52 43 32 01 04 03 49
42 4D 45 4E 56 45 4C 4F
<-- 50 45 01 FF FF FF F0
FF FD 18 -->
<-- FF FB 18
FF FA 18 01 FF F0 -->
FF FA 18 00 49 42 4D 2D
<-- 33 38 31 32 2D 31 FF F0
FF FD 00 -->
<-- FF FB 00
FF FD 19 -->

Murphy, et al. Informational [Page 19]

RFC 2877 5250 Telnet Enhancements July 2000

FF FB 19

9. Telnet Printer Startup Response Record for Printer Emulators

Once Telnet negotiation for a 5250 pass-through mode is completed,
the 5250 Telnet server will initiate a virtual printer power-on
sequence on behalf of the Telnet client. The Telnet server will
supply a Startup Response Record to the Telnet client with the status
of the printer power-on sequence, indicating success or failure of
the virtual printer power-on sequence.

This section shows an example of two Startup Response Records. The
source device is a type 3812 model 01 printer with name "PCPRINTER"
on the target system "TARGET".

Figure 1 shows an example of a successful response; Figure 2 shows an
example of an error response.

9.1 Example of a Success Response Record

The response record in Figure 1 was sent by an AS/400 at Release
V4R2. It is an example of the target sending back a successful
Startup Response Record.

+------------------------------------------------------------------+
| +----- Pass-Through header |
| | +--- Response data |
| | | +---- Start diagnostic information|
| | | | |
| +----------++----------++--------------------------------------- |
| | || || |
| 004912A090000560060020C0003D0000C9F9F0F2E3C1D9C7C5E34040D7C3D7D9 |
| | | T A R G E T P C P R |
| +------+ |
| Response Code (I902) |
| |
| ---------------------------------------------------------------- |
| |
| C9D5E3C5D9400000000000000000000000000000000000000000000000000000 |
| I N T E R |
| |
| +------- End of diagnostic information |
| | |
| -----------------+ |
| | |
| 000000000000000000 |
+------------------------------------------------------------------+
Figure 1. Example of a success response record.

Murphy, et al. Informational [Page 20]

RFC 2877 5250 Telnet Enhancements July 2000

- '0049'X = Length pass-through data, including this length field
- '12A0'X = GDS LU6.2 header
- '90000560060020C0003D0000'X = Fixed value fields
- 'C9F9F0F2'X = Response Code (I902)
- 'E3C1D9C7C5E34040'X = System Name (TARGET)
- 'D7C3D7D9C9D5E3C5D940'X = Object Name (PCPRINTER)

9.2 Example of an Error Response Record

The response record in Figure 2 is one that reports an error. The
virtual device named "PCPRINTER", is not available on the target
system "TARGET", because the device is not available. You would
normally see this error if the printer was already assigned to
another Telnet session.

+------------------------------------------------------------------+
| +----- Pass-Through header |
| | +--- Response data |
| | | +---- Start diagnostic information|
| | | | |
| +----------++----------++--------------------------------------- |
| | || || |
| 004912A09000056006008200003D0000F8F9F0F2E3C1D9C7C5E34040D7C3D7D9 |
| | | T A R G E T P C P R |
| +------+ |
| Response Code (8902) |
| |
| ---------------------------------------------------------------- |
| |
| C9D5E3C5D9400000000000000000000000000000000000000000000000000000 |
| I N T E R |
| |
| +------- End of diagnostic information |
| | |
| -----------------+ |
| | |
| 000000000000000000 |
+------------------------------------------------------------------+
Figure 2. Example of an error response record.

- '0049'X = Length pass-through data, including this length field
- '12A0'X = GDS LU6.2 header
- '90000560060020C0003D0000'X = Fixed value fields
- 'F8F9F0F2'X = Response Code (8902)
- 'E3C1D9C7C5E34040'X = System Name (TARGET)
- 'D7C3D7D9C9D5E3C5D940'X = Object Name (PCPRINTER)

Murphy, et al. Informational [Page 21]

RFC 2877 5250 Telnet Enhancements July 2000

9.3 Response Codes

The Start-Up Response Record success response codes:

CODE DESCRIPTION
---- ------------------------------------------------------
I901 Virtual device has less function than source device
I902 Session successfully started
I906 Automatic sign-on requested, but not allowed.
Session still allowed; a sign-on screen will be
coming.

The Start-Up Response Record error response codes:

CODE DESCRIPTION
---- ------------------------------------------------------
2702 Device description not found.
2703 Controller description not found.
2777 Damaged device description.
8901 Device not varied on.
8902 Device not available.
8903 Device not valid for session.
8906 Session initiation failed.
8907 Session failure.
8910 Controller not valid for session.
8916 No matching device found.
8917 Not authorized to object.
8918 Job canceled.
8920 Object partially damaged.
8921 Communications error.
8922 Negative response received.
8923 Start-up record built incorrectly.
8925 Creation of device failed.
8928 Change of device failed.
8929 Vary on or vary off failed.
8930 Message queue does not exist.
8934 Start-up for S/36 WSF received.
8935 Session rejected.
8936 Security failure on session attempt.
8937 Automatic sign-on rejected.
8940 Automatic configuration failed or not allowed.
I904 Source system at incompatible release.

Murphy, et al. Informational [Page 22]

RFC 2877 5250 Telnet Enhancements July 2000

10. Printer Steady-State Pass-Through Interface

The information in this section applies to the passthrough session
after the receipt of startup confirmation records is complete.

Following is the printer header interface used by Telnet.

+------------------------------------------------------------------+
| +-- Length of structure (LLLL) |
| | |
| | +-- GDS identifier |
| | | |
| | | +-- Data flow record |
| | | | |
| | | | +-- Length of pass-through specific header (LL) |
| | | | | |
| | | | | +-- Flags |
| | | | | | |
| | | | | | +-- Printer operation code |
| | | | | | | |
| | | | | | | +-- Diagnostic field - zero pad to|
| | | | | | | | LL specified |
| | | | | | | | |
| | | | | | | | +-- Printer data |
| | | | | | | | | |
| +--+ +--+ +--+ ++ +--+ ++ +----------+ +----------------+ |
| | | | | | | || | | || | | | | |
| xxxx 12A0 xxxx xx xxxx xx xxxxxxxxxxxx ... print data ... |
| |
+------------------------------------------------------------------+
Figure 3. Layout of the printer pass-through header

BYTES 0-1: Length of structure including this field (LLLL)

BYTES 2-3: GDS Identifier ('12A0'X)

BYTE 4-5: Data flow record

This field contains flags that describe what type of
data pass-through should expect to find following this
header. Generally, bits 0-2 in the first byte are
mutually exclusive (that is, if one of them is set to '
1'B, the rest will be set to '0'B.) The bits, and their
meanings follow.

Murphy, et al. Informational [Page 23]

RFC 2877 5250 Telnet Enhancements July 2000

BIT DESCRIPTION

0 Start-Up confirmation
1 Termination record
2 Start-Up Record
3 Diagnostic information included
4 - 5 Reserved
6 Reserved
7 Printer record
8 - 13 Reserved
14 Client-originated (inbound) printer record
15 Server-originated (outbound) printer record

BYTE 6: Length printer pass-through header including this
field (LL)

BYTES 7-8: Flags

BYTE 7 BITS: xxxx x111 --> Reserved
xxxx 1xxx --> Last of chain
xxx1 xxxx --> First of chain
xx1x xxxx --> Printer now ready
x1xx xxxx --> Intervention Required
1xxx xxxx --> Error Indicator

BYTE 8 BITS: xxxx xxxx --> Reserved

BYTE 9: Printer operation code

'01'X Print/Print complete
'02'X Clear Print Buffers

BYTE 10-LL: Diagnostic information (1)

If BYTE 7 = xx1x xxxx then bytes 10-LL may contain:
Printer ready C9 00 00 00 02

If BYTE 7 = x1xx xxxx then bytes 10-LL may contain: (2)
Command/parameter not valid C9 00 03 02 2x
Print check C9 00 03 02 3x
Forms check C9 00 03 02 4x
Normal periodic condition C9 00 03 02 5x
Data stream error C9 00 03 02 6x
Machine/print/ribbon check C9 00 03 02 8x

If BYTE 7 = 1xxx xxxx then bytes 10-LL may contain: (3)
Cancel 08 11 02 00
Invalid print parameter 08 11 02 29

Murphy, et al. Informational [Page 24]

RFC 2877 5250 Telnet Enhancements July 2000

Invalid print command 08 11 02 28

Diagnostic information notes:

1. LL is the length of the structure defined in Byte 6. If no
additional data is present, the remainder of the structure must
be padded with zeroes.

2. These are printer SIGNAL commands. Further information on these
commands may be obtained from the 5494 Remote Control Unit
Functions Reference guide [2]. Refer to your AS/400 printer
documentation for more specific information on these data stream
exceptions. Some 3812 and 5553 errors that may be seen:

Machine check C9 00 03 02 11
Graphics check C9 00 03 02 26
Print check C9 00 03 02 31
Form jam C9 00 03 02 41
Paper jam C9 00 03 02 47
End of forms C9 00 03 02 50
Printer not ready C9 00 03 02 51
Data stream - class 1 C9 00 03 02 66 loss of text
Data stream - class 2 C9 00 03 02 67 text appearance
Data stream - class 3 C9 00 03 02 68 multibyte control error
Data stream - class 4 C9 00 03 02 69 multibyte control parm
Cover unexpectedly open C9 00 03 02 81
Machine check C9 00 03 02 86
Machine check C9 00 03 02 87
Ribbon check C9 00 03 02 88

3. These are printer negative responses. Further information on
these commands may be obtained from the 5494 Remote Control Unit
Functions Reference guide [2].

The print data will start in byte LL+1.

10.1 Example of a Print Record

Figure 4 shows the server sending the client data with a print
record. This is normally seen following receipt of a Success
Response Record, such as the example in Figure 1.

Murphy, et al. Informational [Page 25]

RFC 2877 5250 Telnet Enhancements July 2000

+--------------------------------------------------------------------+
| +-- Length of structure (LLLL) |
| | +-- GDS identifier |
| | | +-- Data flow record |
| | | | +-- Length of pass-through specific header (LL) |
| | | | | +-- Flags |
| | | | | | +-- Printer operation code |
| | | | | | | +-- Zero pad to LL specified (0A) |
| | | | | | | | +-- Printer data |
| | | | | | | | | |
| +--+ +--+ +--+ ++ +--+ ++ +----------+ +---------------------------|
| | | | | | | || | | || | | | |
| 0085 12A0 0101 0A 1800 01 000000000000 34C4012BD20345FF2BD2044C0002|
| |
| ------------------------------------------------------------ |
| |
| 2BD2040D00002BD20A8501010201030204022BD20309022BD2061100014A |
| |
| ------------------------------------------------------------ |
| |
| 402BD20601010000012BD306F60000FFFF2BD20A48000001000000010100 |
| |
| ------------------------------------------------------------ |
| |
| 2BD10705000B0090012BD2044900F02BD206404A403DE02BD2041500F034 |
| |
| end of printer data |
| -------------------------+ |
| | |
| C4012BD10381FF002BC8034001 |
+--------------------------------------------------------------------+
Figure 4. Server sending client data with a print record

- '0085'X = Logical record length, including this byte (LLLL)
- '12A0'X = GDS LU6.2 header
- '0101'X = Data flow record (server to client)
- '0A'X = Length of pass-through specific header (LL)
- '1800'X = First of chain / Last of chain indicators
- '01'X = Print
- '000000000000'X = Zero pad header to LL specified
- '34C401'X = First piece of data for spooled data
- Remainder is printer data/commands/orders

Murphy, et al. Informational [Page 26]

RFC 2877 5250 Telnet Enhancements July 2000

10.2 Example of a Print Complete Record

Figure 5 shows the client sending the server a print complete record.
This would normally follow receipt of a print record, such as the
example in Figure 4. This indicates successful completion of a print
request.

+-------------------------------------------------------------------+
| +-- Length of structure (LLLL) |
| | +-- GDS identifier |
| | | +-- Data flow record |
| | | | +-- Length of pass-through specific header (LL) |
| | | | | +-- Flags |
| | | | | | +-- Printer operation code |
| | | | | | | |
| +--+ +--+ +--+ ++ +--+ ++ |
| | | | | | | || | | || |
| 000A 12A0 0102 04 0000 01 |
+-------------------------------------------------------------------+
Figure 5. Client sending server a print complete record

- '000A'X = Logical record length, including this byte (LLLL)
- '12A0'X = GDS LU6.2 header
- '0102'X = Data flow response record (client to server)
- '04'X = Length of pass-through specific header (LL)
- '0000'X = Good Response
- '01'X = Print Complete

10.3 Example of a Null Print Record

Figure 6 shows the server sending the client a null print record.
The null print record is the last print command the server sends to
the client for a print job, and indicates to the printer there is no
more data. The null data byte '00'X is optional, and in some cases
may be omitted (in particular, this scenario occurs in DBCS print
streams).

This example would normally follow any number of print records, such
as the example in Figure 4. This indicates successful completion of
a print job. The client normally responds to this null print record
with another print complete record, such as in Figure 5.

Murphy, et al. Informational [Page 27]

RFC 2877 5250 Telnet Enhancements July 2000

+------------------------------------------------------------------+
| +-- Length of structure (LLLL) |
| | +-- GDS identifier |
| | | +-- Data flow record |
| | | | +-- Length of pass-through specific header (LL) |
| | | | | +-- Flags |
| | | | | | +-- Printer operation code |
| | | | | | | +-- Zero pad to LL specified (0A) |
| | | | | | | | +-- Printer data |
| | | | | | | | | |
| +--+ +--+ +--+ ++ +--+ ++ +----------+ ++ |
| | | | | | | || | | || | | || |
| 0011 12A0 0101 0A 0800 01 000000000000 00 |
+------------------------------------------------------------------+
Figure 6. Server sending client a null print record

- '0011'X = Logical record length, including this byte
- '12A0'X = GDS LU6.2 header
- '0101'X = Data flow record
- '0A'X = Length of pass-through specific header (LL)
- '0800'X = Last of Chain
- '01'X = Print
- '000000000000'X = Zero pad header to LL specified
- '00'X = Null data byte

11. End-to-End Print Example

The next example shows a full print exchange between a Telnet client
and server for a 526 byte spooled file. Selective translation of the
hexadecimal streams into 1) Telnet negotiations and 2) ASCII/EBCDIC
characters are done to aid readability. Telnet negotiations are
delimited by '(' and ')' parenthesis characters; ASCII/EBCDIC
conversions are bracketed by '|' vertical bar characters.

AS/400 Telnet server Enhanced Telnet client
------------------------------- ---------------------------------
FFFD27 -->

(IAC DO NEW-ENVIRON)
<-- FFFB27

(IAC WILL NEW-ENVIRON)

FFFD18FFFA270103 49424D5253454544
7EA5DFDDFD300404 0003FFF0 -->

(IAC DO TERMINAL-TYPE
IAC SB NEW-ENVIRON SEND USERVAR

Murphy, et al. Informational [Page 28]

RFC 2877 5250 Telnet Enhancements July 2000

IBMRSEED xxxxxxxx VAR USERVAR
IAC SE)

<-- FFFB18

(IAC WILL TERMINAL-TYPE)

FFFA1801FFF0 -->

(IAC SB TERMINAL-TYPE SEND IAC
SE)

FFFA27000349424D 52534545447EA5DF
DDFD300404000344 45564E414D450144
554D4D5950525403 49424D4D5347514E
414D450151535953 4F50520349424D4D
5347514C4942012A 4C49424C0349424D
464F4E5401313103 49424D5452414E53
464F524D01310349 424D4D4652545950
4D444C012A485049 490349424D505052
5352433101020103 49424D5050525352
433201040349424D 454E56454C4F5045
01FFFF0349424D41 5343494938393901
<-- 30FFF0

(IAC SB NEW-ENVIRON IS USERVAR
IBMRSEED xxxxxxxx VAR
USERVAR DEVNAME VALUE DUMMYPRT
USERVAR IBMMSGQNAME VALUE QSYSOPR
USERVAR IBMMSGQLIB VALUE *LIBL
USERVAR IBMFONT VALUE 11
USERVAR IBMTRANSFORM VALUE 1
USERVAR IBMMFRTYPMDL VALUE *HPII
USERVAR IBMPPRSRC1 VALUE ESC '01'X
USERVAR IBMPPRSRC2 VALUE '04'X
USERVAR IBMENVELOPE VALUE IAC
USERVAR IBMASCII899 VALUE 0
IAC SE)

<-- FFFA180049424D2D 333831322D31FFF0

(IAC SB TERMINAL-TYPE IS
IBM-3812-1 IAC SE)
FFFD19 -->

(IAC DO EOR)
<-- FFFB19

Murphy, et al. Informational [Page 29]

RFC 2877 5250 Telnet Enhancements July 2000

(IAC WILL EOR)

FFFB19 -->

(IAC WILL EOR)
<-- FFFD19

(IAC DO EOR)
FFFD00 -->

(IAC DO BINARY)
<-- FFFB00

(IAC WILL BINARY)
FFFB00 -->

(IAC WILL BINARY)
<-- FFFD00

(IAC DO BINARY)

004912A090000560 060020C0003D0000 | - { |
C9F9F0F2C5D3C3D9 E3D7F0F6C4E4D4D4 |I902ELCRTP06DUMM| (EBCDIC)
E8D7D9E340400000 0000000000000000 |YPRT |
0000000000000000 0000000000000000 | |
0000000000000000 00FFEF --> | |

(73-byte startup success response
record ... IAC EOR)
00DF12A001010A18 0001000000000000 | |
03CD1B451B283130 551B287330703130 | E (10U (s0p10| (ASCII)
2E30306831327630 733062303033541B |.00h12v0s0b003T |
287330421B266440 1B266C304F1B266C |(s0B &d@ &l0O &l|
303038431B266C30 3035431B28733070 |008C &l005C (s0p|
31372E3130683130 7630733062303030 |17.10h10v0s0b000|
541B283130551B28 73307031372E3130 |T (10U (s0p17.10|
6831307630733062 303030541B287330 |h10v0s0b000T (s0|
421B2664401B266C 314F1B266C303035 |B &d@ &l1O &l005|
431B287330703137 2E31306831307630 |C (s0p17.10h10v0|
733062303030541B 266C314F1B287330 |s0b000T &l1O (s0|
7031372E31306831 3076307330623030 |p17.10h10v0s0b00|
30541B2873307031 372E313068313076 |0T (s0p17.10h10v|
3073306230303054 1B266C30303543FF |0s0b000T &l005C |
EF --> | |

(... 223-byte print record ...
... first of chain ...
... last of chain ... IAC EOR)

Murphy, et al. Informational [Page 30]

RFC 2877 5250 Telnet Enhancements July 2000

<-- 000A12A001020400 0001FFEF

(10-byte print complete header)
031012A001010A10 0001000000000000 | |
03FFFF1B451B2831 30551B2873307031 | E (10U (s0p1| (ASCII)
372E313068313076 3073306230303054 |7.10h10v0s0b000T|
1B287330421B2664 401B266C314F1B26 | (s0B &d@ &l1O &|
6C303035431B266C 31481B266C314F1B |l005C &l1H &l1O |
266C3032411B266C 31431B266C303030 |&l02A &l1C &l000|
38451B266C303038 431B266C30303439 |8E &l008C &l0049|
461B266130521B26 6C303035430A0A0A |F &a0R &l005C |
0A0A0A0A1B26612B 3030303130561B26 | &a+00010V &|
6C303035431B2661 2B30303231364820 |l005C &a+00216H |
2020202020202020 2020202020202020 | |
2020202020205072 696E74204B657920 | Print Key |
4F75747075742020 2020202020202020 |Output |
2020202020202020 2020202020202020 | |
2020202020205061 6765202020310D0A | Page 1 |
1B26612B30303231 3648202020203537 | &a+00216H 57|
3639535331205634 52334D3020393830 |69SS1 V4R3M0 980|
373203FFFF392020 2020202020202020 |72 9 |
202020202020454C 4352545030362020 | ELCRTP06 |
2020202020202020 202030332F33312F | 03/31/|
3939202031363A33 303A34350D0A1B26 |99 16:30:45 &|
612B303032313648 0D0A1B26612B3030 |a+00216H &a+00|
3231364820202020 446973706C617920 |216H Display |
4465766963652020 2E202E202E202E20 |Device . . . . |
2E203A2020515041 444556303033510D |. : QPADEV003Q |
0A1B26612B303032 3136482020202055 | &a+00216H U|
73657220202E202E 202E202E202E202E |ser . . . . . .|
202E202E202E202E 203A202052434153 | . . . . : RCAS|
54524F0D0A1B2661 2B3030323136480D |TRO &a+00216H |
0A1B26612B303032 313648204D41494E | &a+00216H MAIN|
2020202020202020 2020202020202020 | |
2020202020202020 20202041532F3430 | AS/40|
30204D61696E204D 656E750D0A1B2661 |0 Main Menu &a|
2B30303203FFFF31 3648202020202020 |+002 16H |
2020202020202020 2020202020202020 | |
2020202020202020 2020202020202020 | |
2020202020202020 2020202020202020 | |
2020202020202053 797374656D3A2020 | System: |
20454C4352545030 360D0A1B26612B30 | ELCRTP06 &a+0|
3032313648205365 6C656374206F6E65 |0216H Select one|
206F662074686520 666F6C6C6F77696E | of the followin|
673A0D0A1B26612B 3030323136480D0A |g: &a+00216H |
1B26612B30303231 3648202020202020 | &a+00216H |
312E205573657220 7461736B730D0A1B |1. User tasks |
26612B3030323136 4820202020202032 |&a+00216H 2|

Murphy, et al. Informational [Page 31]

RFC 2877 5250 Telnet Enhancements July 2000

2E204F6666696365 207461736B730D0A |. Office tasks |
1B26612B30303231 36480D0A1B26612B | &a+00216H &a+|
3030323136482020 20202020342E2046 |00216H 4. F|
696C65732C206C69 627261726965732C |iles, libraries,|
20616EFFEF | an |

(... 784-byte print record ...
... first of chain ... IAC EOR)
<-- 000A12A001020400 0001FFEF

(10-byte print complete header)

020312A001010A00 0001000000000000 | |
64206603FFFF6F6C 646572730D0A1B26 |d f olders &| (ASCII)
612B303032313648 0D0A1B26612B3030 |a+00216H &a+00|
3231364820202020 2020362E20436F6D |216H 6. Com|
6D756E6963617469 6F6E730D0A1B2661 |munications &a|
2B3030323136480D 0A1B26612B303032 |+00216H &a+002|
3136482020202020 20382E2050726F62 |16H 8. Prob|
6C656D2068616E64 6C696E670D0A1B26 |lem handling &|
612B303032313648 202020202020392E |a+00216H 9.|
20446973706C6179 2061206D656E750D | Display a menu |
0A1B26612B303032 3136482020202020 | &a+00216H |
31302E20496E666F 726D6174696F6E20 |10. Information |
417373697374616E 74206F7074696F6E |Assistant option|
730D0A1B26612B30 3032313648202020 |s &a+00216H |
202031312E20436C 69656E7420416363 | 11. Client Acc|
6573732F34303020 7461736B730D0A1B |ess/400 tasks |
26612B3030323136 480D0A1B26612B30 |&a+00216H &a+0|
303231364803ED20 2020202039302E20 |0216H 90. |
5369676E206F6666 0D0A1B26612B3030 |Sign off &a+00|
323136480D0A1B26 612B303032313648 |216H &a+00216H|
2053656C65637469 6F6E206F7220636F | Selection or co|
6D6D616E640D0A1B 26612B3030323136 |mmand &a+00216|
48203D3D3D3E0D0A 1B26612B30303231 |H ===> &a+0021|
36480D0A1B26612B 3030323136482046 |6H &a+00216H F|
333D457869742020 2046343D50726F6D |3=Exit F4=Prom|
707420202046393D 5265747269657665 |pt F9=Retrieve|
2020204631323D43 616E63656C202020 | F12=Cancel |
4631333D496E666F 726D6174696F6E20 |F13=Information |
417373697374616E 740D0A1B26612B30 |Assistant &a+0|
3032313648204632 333D53657420696E |0216H F23=Set in|
697469616C206D65 6E750D0A1B26612B |itial menu &a+|
3030323136480D0A 1B26612B30303231 |00216H &a+0021|
36480D0CFFEF |6H |

(... 515-byte print record ...
IAC EOR)

Murphy, et al. Informational [Page 32]

RFC 2877 5250 Telnet Enhancements July 2000

<-- 000A12A001020400 0001FFEF

(10-byte print complete header)
001412A001010A00 0001000000000000 | |
03021B45FFEF | E | (ASCII)

(... 20-byte print record ...
IAC EOR)
<-- 000A12A001020400 0001FFEF

(10-byte print complete header)
001112A001010A08 0001000000000000
00FFEF -->

(... 17-byte NULL print record ...
... last of chain ... IAC EOR)
<-- 000A12A001020400 0001FFEF

(10-byte print complete header)

12. Authors' Note

Discussion of this memo should occur in one of these mailing lists:

TN3270E List (Roger Fajman [email protected]). Send subscription
requests as e-mail with "subscribe tn3270e your_full_name" to
[email protected].

Midrange-L List (David Gibbs [email protected]). Send
subscription requests as email with "subscribe midrange-l
your_internet_address" to [email protected].

Telnet Working Group Mailing List: Send subscription requests as
email with "subscribe telnet-ietf" to telnet-ietf-
[email protected].

13. References

[1] IBM, "IBM 5250 Information Display System, Functions Reference
Manual", SA21-9247-6, March 1987.

[2] IBM, "5494 Remote Control Unit, Functions Reference", SC30-
3533-04, August 1995.

[3] IBM, "AS/400 System API Reference", SC41-5801-01, February
1998.

Murphy, et al. Informational [Page 33]

RFC 2877 5250 Telnet Enhancements July 2000

[4] IBM, "AS/400 TCP/IP Configuration and Reference", SC41-5420-02,
September 1998.

[5] IBM, "AS/400 Communications Configuration", SC41-5401-00,
August 1997.

[6] IBM, "SNA Formats", GA27-3136-13, November 1993.

[7] IBM, "Using the Pageprinter 3812 with System/36 or System/38",
S544-3343-01, September 1997.

[8] Postel, J. and J. Reynolds, "Telnet Protocol Specification",
STD 8, RFC 854, May 1983.

[9] Postel, J. and J. Reynolds, "Telnet Option Specifications", STD
8, RFC 855, May 1983.

[10] Postel, J. and J. Reynolds, "Telnet Binary Transmission", STD
27, RFC 856, May 1983.

[11] VanBokkeln, J., "Telnet Terminal-Type Option", RFC 1091,
February 1989.

[12] Postel, J. and J. Reynolds, "Telnet End of Record Option", RFC
885, December 1983.

[13] Alexander, S., "Telnet Environment Option", RFC 1572, January
1994.

[14] Chmielewski, P., "5250 Telnet Interface", RFC 1205, February
1991.

[15] Postel, J. and J. Reynolds, "Telnet Supress Go Ahead Option",
STD 29, RFC 858, May 1983.

[16] IBM, "AS/400 National Language Support", SC41-5101-01, February
1998.

[17] Data Encryption Standard (DES), Federal Information Processing
Standards Publication 46-2, January 22, 1988.

[18] DES Modes of Operation, Federal Information Processing
Standards Publication 81, December 1980.

[19] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC
1700, October 1994.

[20] IBM, "IBM Pageprinter 3812 Programming Reference", S544-3268.

Murphy, et al. Informational [Page 34]

RFC 2877 5250 Telnet Enhancements July 2000

14. Security Considerations

Security considerations of passwords are discussed in Section 6.

15. Authors' Addresses

Thomas E. Murphy, Jr.
IBM Corporation
1701 North Street
Endicott, NY 13760

Phone: (607) 752-5482
Fax: (607) 752-5421
EMail: [email protected]

Paul F. Rieth
IBM Corporation
1701 North Street
Endicott, NY 13760

Phone: (607) 752-5474
Fax: (607) 752-5421
EMail: [email protected]

Jeffrey S. Stevens
IBM Corporation
1701 North Street
Endicott, NY 13760

Phone: (607) 752-5488
Fax: (607) 752-5421
EMail: [email protected]

16. Relation to Other RFC's

UPDATES

This memo is an update to RFC 1205 [14], which describes the 5250
Telnet Interface. This update enhances that description to
include device negotiation as well as printer support.

This memo makes use of RFC 1572 [13] to enhance communications
with 5250 Telnet clients. RFC 1572 is currently on the Standards
Track as a Proposed Standard, and is listed in Assigned Numbers
[19].

Murphy, et al. Informational [Page 35]

RFC 2877 5250 Telnet Enhancements July 2000

17. Full Copyright Statement

Copyright (C) The Internet Society (2000). 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.

Murphy, et al. Informational [Page 36]