IV26784: UA:LINUX ONLY, UA STOPS MONITORING SNMP TRAPS WHEN CHECKSUM ERROR RECEIVED

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • When UA received a checksum error in the packet received from
    snmp trap, kumstrap exits automatically.
    
    kumstrap.log entries:
    ----------------------
    50305C51 ----- Trap socket select completed. nfds=1
    50305C51 ----- Checking trapSSE ReadMasks
    50305C51 ----- Clearing ReadMask for IPv4 socket 4
    50305C51 ----- Socket 4 selected for UDP data, addrlen 16
    50305C51 ***** trap receive error on socket 4, errno 11 addrlen
    16
    
    
    kumstrap exit:
    ----------------------
    13:24:01.516639 recvfrom(4, 0x7fff7d868600, 4000, 0,
    0x7fff7d868180, 0x7fff7d86817c) = -1 EAGAIN (Resource
    temporarily unavailable)
    13:24:01.536794 write(3, "50305C15 ----- Socket 4 added to"...,
    324) = 324
    13:24:01.536981 close(3)                = 0
    13:24:01.537078 munmap(0x7f5283a7d000, 4096) = 0
    13:24:01.548795 exit_group(0)           = ?
    
    
    Modify the UA code for Linux only to suppress the 'exit
    logic' and instead to reissue the socket select() call.
    

Local fix

Problem summary

  • Universal Agent on LINUX only, stops monitoring SNMP traps when
    Checksum error received
    
    
    When software that emits SNMP trap injects CheckSum error in the
    trap data, Linux O/S socket select() API does not cope with this
    circumstance, falsely returning success status on 'select'.
    Subsequent socket recvfrm() API fails to receive data since
    there is no valid data.
    
    Universal Agent SNMP trap 'listening' code is a continuous loop,
    thus implemented design was to exit from the loop on recvfrm()
    failure and terminate the SNMP trap 'listening' thread;
    otherwise Universal Agent could potentially fall into a tight,
    infinite loop of repeatedly issuing recvrm() calls that return
    failed status.
    

Problem conclusion

  • Customer resolved problem by correcting CheckSum error in their
    Perl script.
    
    APAR fix only delivers nominal enhancement to Universal Agents's
    reaction to bad data arriving on SNMP trap listening socket.
    This APAR "fix" added a counter that checks for 5 consecutive
    recvfrm() failures and if so then original Universal Agent
    behavior of exiting from loop on recvfrm() failure and
    terminating SNMP trap 'listening' thread is carried out -  this
    APAR can not fix a customer's code.
    
    The fix for this APAR is included in the following maintenance
    vehicle:
    
       | fix pack | 6.2.3-TIV-ITM-FP0003
    
    Note: Search the IBM technical support web site for maintenance
    package availability.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV26784

  • Reported component name

    UNIVERSAL AGENT

  • Reported component ID

    5724K1000

  • Reported release

    622

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-08-21

  • Closed date

    2012-11-05

  • Last modified date

    2013-05-06

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

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

Fix information

  • Fixed component name

    UNIVERSAL AGENT

  • Fixed component ID

    5724K1000

Applicable component levels

  • R623 PSY

       UP



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Document information


More support for:

Tivoli Universal Agent

Software version:

622

Reference #:

IV26784

Modified date:

2013-05-06

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