OA06318: FTP FAILS WITH 425 CAN'T BUILD DATA CONNECTION: ADDRESS ALREADYIN USE.

Obtain the fix for this APAR.

APAR status

• Closed as unreproducible.

Error description

• FTP fails with "425 Can't build data connection:  Address
  already in use".  This occurs for USERS that are coding
  TCPSTACKSOURCEVIPA.  The problem is that when a port is
  released it goes to the top of the stack for reuse.
  Timing can cause this port to still be in use when it
  it is reused in a short period of time.
  

Local fix

• Do not use TCPSTACKSOURCEVIPA until this fix is applied.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All using SYSPLEXPORTS to distribute         *
  *                 SOURCEVIPA.  SYSPLEXDS                       *
  ****************************************************************
  * PROBLEM DESCRIPTION: FTP failure 425  Can't build data       *
  *                      connection:   Address already in use    *
  *                      after issuing two NLST commands.        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The problem is occurring because the FTP client is issuing the
  same PORT command for each of the NLST commands.  The second
  NLST fails because it takes 2 minutes for the port to be
  available again after it has been closed.
  
  In the SYSPLEXPORTs environment, when a port is released it
  goes back on the list of available ports. When a port request
  is received, the search always starts at the beginning of the
  list. This can result in the same port being reassigned in
  a short period of time. If the port is not completely ready,
  the address already in use, error may occur.
  

Problem conclusion

Temporary fix

Comments

• This problem was fixed in ISTFSVEF by changing the loop to
  find the next available port. The loop now saves the last
  assigned port and begins the search there. When the end of
  matrix is reached the search resumes at the beginning of the
  matrix. This will result in all available ports being used
  before a released port is reused.
  ISTFSVPC was recompiled to pickup the change to ISTSSVCB.
  

APAR Information

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

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

  UA09021

Modules/Macros

• ISTFSVEF ISTFSVPC ISTSSVCB
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R140 PSY UA09021

     UP04/04/14 P F404

Fix is available

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