LARGE SECURE FTP TRANSFER BOGS DOWN AND HANGS SSL SESSIONS

 
 APAR Identifier ...... PI68525      Last Changed ........ 17/02/01
 LARGE SECURE FTP TRANSFER BOGS DOWN AND HANGS SSL SESSIONS
 
 Symptom ...... IN INCORROUT         Status ........... CLOSED  PER
 Severity ................... 2      Date Closed ......... 17/01/25
 Component .......... 5735FAL00      Duplicate of ........
 Reported Release ......... 630      Fixed Release ............ 999
 Component Name TCP/IP V2 FOR V      Special Notice
 Current Target Date ..              Flags
 SCP ...................
 Platform ............
 
 Status Detail: SHIPMENT - Packaged solution is available for
                           shipment.
 
 PE PTF List:
 
 PTF List:
 Release 630   : UI44207 available 17/02/01 (1000 )
 Release 640   : UI44208 available 17/02/01 (1000 )
 
 Parent APAR:
 Child APAR list:
 
 ERROR DESCRIPTION:
 When a secure FTP PUT is done of a large file (e.g., 6.5GB), the
 data transfer slows down to a crawl and all access to the system
 via SSL (secure TELNET sessions) hangs up.  The problem occurs
 when the TCPIP stack has reached the 10% threshold for the
 number of available data buffers and it is preceded by buffer
 depletion warnings on the TCPIP console.
 
 LOCAL FIX:
 
 PROBLEM SUMMARY:
 ****************************************************************
 * USERS AFFECTED: All users of the z/VM TCP/IP                 *
 ****************************************************************
 * PROBLEM DESCRIPTION:                                         *
 ****************************************************************
 * RECOMMENDATION: APPLY PTF                                    *
 ****************************************************************
 When a secure FTP PUT is done of a large file (e.g., 6.5GB), the
 data transfer slows down to a crawl and all access to the system
 via SSL (secure TELNET sessions) hangs up.  The problem occurs
 when the TCPIP stack has reached the 10% threshold for the
 number of available data buffers and it is preceded by buffer
 depletion warnings on the TCPIP console.
 
 PROBLEM CONCLUSION:
 The fix includes changes for the FTP server, SSL server and
 TCP/IP stack
 
 FTP server
 If the control connection is closed while the data connection
 is still opened to store the file, the FTP server will issue
 the abort function to make sure the data connection is
 closed as expected.
 
 FTSCMD is updated to initialize the flags when a new data
 connection is opened for the given control control connection,
 in order to ensure that the FTP server sends one and
 only one '150' reply to any subsequent data transfer command
 that is received.
 
 SSL server
 If the SSL server gets the EWOULDBLOCK return code when it is
 writing the clear data out, the server will continue to run,
 instead of closing the connection.
 
 TCP/IP stack
 1. Change TCPSSL and T6PSSL to make the secure socket that is
    created non-blocking
 2. Update F6TCPREQ to pull in APAR PQ95009, APAR PQ95009 was
    put into the IPv4 version of SkTcpWri but was not in the
    IPv6 version of VSkTcpWr. This update adds a check for a
    non-blocking socket when there are not enough buffers for
    the data.
 3. Update TCTREEP so that message 65004 will only be displayed
    when TCPUP tracing is specified
 4. Update TCPREQU to allow an Abort to happen on a connection
    that has a handshake in progress
 5. TCPSSL is updated to free the newly obtained ACB and respond
    to the SSL server when the connection is in the CLOSED state.
 6. TCPSSL is also updated to avoid 2 TCBs pointing to the same
    ACB when copying the TCB.
 
 TEMPORARY FIX:
 
 COMMENTS:
 
 MODULES/MACROS:
 FPTCPDOW FTSCMD   FTSEVEN  FTSUTIL  F6TCPREQ SSLDPUMP TCPREQU
 TCPSSL   TCTREEP  T6PSSL
 
 SRLS:
 NONE
 
 RTN CODES:
 
 CIRCUMVENTION:
 
 MESSAGE TO SUBMITTER: