PI55788: ENHANCEMENT TO HELP PREVENT "GETHOSTBYNAME" TCP/IP CALL FAILURES DUE TO MISSING DNS TABLE ENTRIES

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• IBM Security Guardium S-TAP for IMS on z/OS Version 10 uses
  TCP/IP as an INTRA and INTER host communication path between
  IMS STAP address spaces.  Information that is passed along this
  communications channel includes Collection Policy details and
  address space status updates.
  
  The TCP/IP address to be used is determined by obtaining the
  LPAR name from the CVTSNAME field found in the z/OS System CVT
  control block.
  
  The LPAR name is used as input to a z/OS TCP/IP "gethostbyname"
  service call which obtains the IP address associated with the
  LPAR name from the system DNS resolver table.
  Using this IP address and communications port, the Agent
  address space builds and opens a socket.  The IP address and
  port information are stored in an XCF structure and are made
  available to all LPARS that participate in the Sysplex.  When
  subordinate address spaces (AUIL, AUIF, AUIU) start, they
  access the XCF structure and extract the IP and port
  information.  These subordinate address spaces then use the
  extracted data to establish a connection back to the Agent
  address space.
  
  This process relies on the DNS Resolver table containing
  entries pointing the LPAR names (as defined in the CVTSNAME
  field) to physical IP addresses.
  If these DNS Resolver table entries do not exist, when the IMS
  STAP address spaces attempt to obtain the IP address using the
  "gethostbyname" service, the service will fail and as there is
  no IP address available, communications cannot occur and the
  IMS STAP address spaces will issue appropriate error messages
  and terminate.
  
  A variation of the problem involves the user of Dynamic Virtual
  IP Addressing (VIPA).
  This TCP/IP service allows a customer to associate multiple IP
  addresses to a "host name".
  There are some users of this service who also use a VIPA token
  that is different than the LPAR name as the host identifier.
  The use of this token as the search key when determining the IP
  address, precludes the use of the CVTSNAME value.
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of STAP for IMS V10.0.             *
  ****************************************************************
  * PROBLEM DESCRIPTION: IBM Security Guardium S-TAP for IMS on  *
  *                      z/OS Version 10 uses TCP/IP as an       *
  *                      INTRA and INTER host communication path *
  *                      between IMS STAP address spaces.        *
  *                      Information that is passed along this   *
  *                      communications channel includes         *
  *                      Collection Policy details and address   *
  *                      space status updates.                   *
  *                      The TCP/IP address to be used is        *
  *                      determined by obtaining the LPAR name   *
  *                      from the CVTSNAME field found in the    *
  *                      z/OS System CVT control block.          *
  *                      The LPAR name is used as input to a     *
  *                      z/OS TCP/IP gethostbyname service       *
  *                      call which obtains the IP address       *
  *                      associated with the LPAR name from the  *
  *                      system DNS resolver table. Using this   *
  *                      IP address and communications port,     *
  *                      the Agent address space builds and      *
  *                      opens a socket. The IP address and      *
  *                      port information are stored in an XCF   *
  *                      structure and are made available to all *
  *                      LPARS that participate in the Sysplex.  *
  *                      When subordinate address spaces (AUIL,  *
  *                      AUIF, AUIU) start, they access the XCF  *
  *                      structure and extract the IP and port   *
  *                      information. These subordinate address  *
  *                      spaces then use the extracted data to   *
  *                      establish a connection back to the      *
  *                      Agent address space.                    *
  *                                                              *
  *                      This process relies on the DNS Resolver *
  *                      table containing entries pointing the   *
  *                      LPAR names (as defined in the CVTSNAME  *
  *                      field) to physical IP addresses.        *
  *                      If these DNS Resolver table entries do  *
  *                      not exist, when the IMS STAP address    *
  *                      spaces attempt to obtain the IP address *
  *                      using the gethostbyname service, the    *
  *                      service will fail and as there is no IP *
  *                      address available, communications       *
  *                      cannot occur and the IMS STAP address   *
  *                      spaces will issue appropriate error     *
  *                      messages and terminate.                 *
  *                                                              *
  *                      A variation of the problem involves the *
  *                      user of Dynamic Virtual IP Addressing   *
  *                      (VIPA). This TCP/IP service allows a    *
  *                      customer to associate multiple IP       *
  *                      addresses to a host name. There are     *
  *                      some users of this service who also use *
  *                      a VIPA token that is different than the *
  *                      LPAR name as the host identifier. The   *
  *                      use of this token as the search key     *
  *                      when determining the IP address,        *
  *                      precludes the use of the CVTSNAME       *
  *                      value.                                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Apply the provided ptf.
  

Problem conclusion

Temporary fix

Comments

• The solution is to provide a method of allowing the customer to
  manually associate the LPAR name found in the z/OS CVTSNAME
  with the name the site uses in their DNS table.
  We will then use that alternate name as input to the
  gethostbyname call in order to obtain the relevant IP address.
  
  The method we will use is the optional addition of an AUIHOST
  DD statement to be included in the AGENT task address space
  JCLs. The AUIHOST file must be included in all IMS STAP
  address space JCLs.
  

APAR Information

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

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

  UI36750

Modules/Macros

• AUIAAACM AUIAATUP AUIAAUGT AUIAAUTP AUIACBIM AUIACLMI AUIACSUI
  AUIADBRD AUIADDLI AUIADORD AUIADT@  AUIAGAIF AUIAGCCH AUIAGDSC
  AUIAGPHN AUIAGQHN AUIAGUDC AUIAMMST AUIAPLMT AUIAPTLG AUICHKPT
  AUIFAGTF AUIFASMM AUIFDT@  AUIFHRDR AUIFSMF  AUIGAADM AUIGADT@
  AUIGAPAD AUIGAPD@ AUIGAPRX AUIGDMIX AUIGDT@  AUIGLDT@ AUIGLNHN
  AUIGLOGR AUIGPING AUIGRDT@ AUIGRLNH AUIGRSD@ AUIGRSGH AUIGRSTR
  AUIGSDT@ AUIGSGHN AUIGSTRS AUIILMG  AUILAIMM AUILDT@  AUILGMSG
  AUILGSMG AUILGSZP AUILIMS  AUILIMSL AUILMAIM AUILMDT@ AUILMLOG
  AUILMMLG AUILMTRD AUILRRDR AUIMGENU AUIMISLG AUIPDT@  AUIPGRDM
  AUIPLGHL AUISFMG  AUITAAS  AUITAGT  AUITCFG  AUITDT@  AUITLOCG
  AUITLOGN AUITRCRD AUITREQ  AUITTHRD AUITTOP  AUITTREQ AUIUACSA
  AUIUACSM AUIUACUT AUIUCSUT AUIUDT@  AUIUMO@  AUIUMSGS AUIURAMG
  AUIURDT@ AUIURMIG AUIUSM@  AUIVIMS0 AUIYCKPT AUIYCSI  AUIYDT@
  AUIZACFB AUIZACFG AUIZACPB AUIZACXB AUIZCFGF AUIZCMN  AUIZCSPB
  AUIZDT@  AUIZIMSV AUIZMO@  AUIZMSGS AUIZPLIN AUIZSLSV AUIZSM@
  AUIZSMAN AUIZSSPC AUIZTCFG
  

Fix information

• Fixed component name

  SEC GUAR STAP I

• Fixed component ID

  5655STM00

Applicable component levels

• RA00 PSY UI36750

     UP16/04/15 P F604

Fix is available

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