Unable to Log On to Host Computer When You Use 3270 Single Sign-On (319419)


The information in this article applies to:

  • Microsoft SNA Server 4.0
  • Microsoft SNA Server 4.0 SP1
  • Microsoft SNA Server 4.0 SP2
  • Microsoft SNA Server 4.0 SP3
  • Microsoft SNA Server 4.0 SP4
  • Microsoft Host Integration Server 2000
This article was previously published under Q319419

SYMPTOMS

If you use a 3270 emulator that is configured to use the Single Sign-On (SSO) feature that is available with SNA Server and Host Integration Server (HIS) 2000, and you try to log on to an application that is running on an IBM mainframe computer, you may receive an error message from the mainframe application that indicates an invalid user ID or password.

The actual symptoms will vary depending on the 3270 emulator that you use and the mainframe application that you try to access.

CAUSE

Under certain conditions, the SNA Server service (Snaservr.exe) may not correctly identify the predefined 3270 SSO replacement strings for the mainframe user ID and password. For example, this problem can occur if the first character of the 3270 replacement string for the mainframe user ID is located just prior to the actual 3270 SSO replacement string.

WORKAROUND

If a duplicate character in the data message that contains the replacement strings causes this behavior, change the 3270 SSO replacement strings. Please refer to the SNA Server or HIS 2000 online documentation for details about the how to change the 3270 SSO replacement strings.

For additional information about 3270 SSO replacement strings, click the article number below to view the article in the Microsoft Knowledge Base:

291805 3270 SSO Fails If 3270SSOUserTag and 3270SSOPwdTag Use Same Value

STATUS

SNA Server 4.0

Microsoft has confirmed that this is a problem in Microsoft SNA Server version 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, and 4.0 SP4.

Host Integration Server 2000

Microsoft has confirmed that this is a problem in Microsoft Host Integration Server 2000.

MORE INFORMATION

The problem described here occurs only under very specific circumstances. The following is an example of one scenario where the problem can occur.

NOTE: This example uses the default 3270 SSO replacement strings (MS$SAMEU and MS$SAMEP).

  1. A 3270 emulator starts and the mainframe application sends a sign-on screen to the 3270 emulator that prompts for the user's host user ID and password.
  2. The 3270 emulator is set up to use a logon script or macro to automate the logon process. The logon script or macro enters the 3270 SSO replacement strings at the user ID and password prompts.
  3. When the 3270 logon script submits the information to the mainframe application, the following message is sent to the SNA Server or HIS 2000 Server for processing.
NOTE: The following message was capture with the SNA Trace program, which captures 3270 message traces. The trace excerpt is annotated to indicate the 3270 SSO replacement strings, which are underlined with carat (^) characters. Also noted in the trace excerpt is an M that is underlined with tilde (~) characters. 

FMI   03120500->01020302 FMI DATA  
FMI                      NO ACK reqd Key:2 Seq:1 FMHI BCI ECI COMMIT
FMI                      BBI EBI CDI SDI CODE ENCRYP ENPAD QRI CEI
FMI                      BBIUI EBIUI RBI 
FMI   
FMI   ---- Header  at address 012244B4, 1 elements ----
FMI   00050002 FFFF2C00 02010001 0100FC08     <......,.........>
FMI   
FMI   ---- Element at address 01C135A4, start 4, end 40 ----
FMI   2C000102 00010390 A07DD6F6 11D4D6D4     <,........}O6.MOM>
                                   ~~  ^^
FMI   E25BE2C1 D4C5E411 D5E6D4E2 5BE2C1D4     <S[SAMEU.NWMS[SAM>
      ^^^^^^^^ ^^^^^^       ^^^^ ^^^^^^^^
FMI   C5D7115C 7D                             <EP.\}           >
      ^^^^
The M that precedes the leading M for the MS$SAMEU replacement string is part of a 3270 Set Buffer Address (SBA) command. Because the M appears prior to the replacement string, the logon script sends an invalid user ID to the mainframe application.
Modification Type:MinorLast Reviewed:3/30/2005
Keywords:kbBug kbnofix KB319419
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