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IT00310: SSP SFTP ADAPATER DOES NOT ALLOW "NONE" COMPRESSION WHEN ZLIB COMPRESSION SELECTED IN THE ADAPTER

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APAR status

  • Closed as program error.

Error description

  • The Manual states that when Zlib compression is chosen both
    Zlib and None compression are supported but during the Key
    exchange on Zlib compression is presented as an option causing
    client that do not support Zlib compression to fail
    
    Compression is controlled by the SFTP Advanced Adapter
    settings, there are two settings "NONE" and zlib documented as
    follows (It's the bit under lined in red that's the probable
    root cause of the problem)
    
    The problem is when zlib is chosen then "none" is not sent as a
    compression option as seen and I can also recreate the issue.
    
    Select "NONE" as the compression option
    
    
    Starting a session results in the debug client output showing
    "none" being sent in the Key Exchange Init
    
    debug2: kex_parse_kexinit: first_kex_follows 0
    debug2: kex_parse_kexinit: reserved 0
    debug2: kex_parse_kexinit:
    diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1,di
    ffie-hellman-group14-sha1
    debug2: kex_parse_kexinit: ssh-rsa
    debug2: kex_parse_kexinit: 3des-cbc
    debug2: kex_parse_kexinit: 3des-cbc
    debug2: kex_parse_kexinit: hmac-sha1,hmac-sha1-96
    debug2: kex_parse_kexinit: hmac-sha1,hmac-sha1-96
    debug2: kex_parse_kexinit: none
    debug2: kex_parse_kexinit: none
    
    and a packet trace shows the "none" coming from the SSP SFTP
    Server.
    
    
    
    Repeating the exercise with "zlib" compression
    
    
    
    This time the Client traces shows only "zlib" being sent as a
    compression option
    
    debug2: kex_parse_kexinit: first_kex_follows 0
    debug2: kex_parse_kexinit: reserved 0
    debug2: kex_parse_kexinit:
    diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1,di
    ffie-hellman-group14-sha1
    debug2: kex_parse_kexinit: ssh-rsa
    debug2: kex_parse_kexinit: 3des-cbc
    debug2: kex_parse_kexinit: 3des-cbc
    debug2: kex_parse_kexinit: hmac-sha1,hmac-sha1-96
    debug2: kex_parse_kexinit: hmac-sha1,hmac-sha1-96
    debug2: kex_parse_kexinit: zlib
    debug2: kex_parse_kexinit: zlib
    
    and confirmed as originating from the SSP SFTP Adapter in the
    packet trace
    
    
    
    The manual states when zlip is chosen then Zlib and None are
    supported, however these does not appear to be the case as only
    zlib is being returned by SSP as a supported compression method
    which will break clients that do not support zlib compression.
    
    SSP should be returning the following Key Exchange Init value
    
    debug2: kex_parse_kexinit: none,zlib
    debug2: kex_parse_kexinit: none,zlib
    

Local fix

  • STRRTC - 415108
    SP/RJ
    Circumvention:
    Update to latest SSP Build
    

Problem summary

  • SFTP Zlib compression not allowing NONE
    Customer coded zlib compression on their SFTP adapter
    configuration  (advanced tab).  Some clients could not connect
    because they did not  want to do compression. The documentation
    stated that specifying zlib  would allow zlib or NONE.
    

Problem conclusion

  • Resolution: Added 2 new options to the SFTP compression field:
       zlib,none  - allows zlib or NONE but makes zlib preferred
       none,zlib  - allows zlib or NONE but makes NONE preferred
    

Temporary fix

  •  Description of issue:
      RTC415108/        (CM, Engine) - SFTP Zlib compression not
    allowing NONE
          Customer coded zlib compression on their SFTP adapter
    configuration (advanced tab).  Some clients could not connect
    because they did not want to do compression. The documentation
    stated that specifying zlib would allow zlib or NONE.
    
     Description of fix:
          Resolution: Added 2 new options to the SFTP compression
    field:
             zlib,none  - allows zlib or NONE but makes zlib
    preferred
             none,zlib  - allows zlib or NONE but makes NONE
    preferred
    

Comments

APAR Information

  • APAR number

    IT00310

  • Reported component name

    STR SECURE PROX

  • Reported component ID

    5725D0300

  • Reported release

    341

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2014-03-13

  • Closed date

    2014-03-24

  • Last modified date

    2014-03-24

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Modules/Macros

  •    None
    NONE
    

Fix information

  • Fixed component name

    STR SECURE PROX

  • Fixed component ID

    5725D0300

Applicable component levels

  • R341 PSY

       UP

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Document Information

Modified date:
24 March 2014