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MF58590 - TCPIP-TELNET-UNPRED VLOG 0701005D TELNET CLIENTS DROPPED

PTF ( Program Temporary Fixes ) Cover letter


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Abstract

TCPIP-TELNET-UNPRED VLOG 0701005D TELNET CLIENTS DROPPED


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED           PTF/FIX  LEVEL

TYPE PROGRAM  RELEASE   NUMBER   MIN/MAX  OPTION
---- -------- --------- -------  -------  ------
NONE



NOTICE:
-------
Application of this PTF may disable or render ineffective programs that
use system memory addresses not generated by the IBM translator,
including programs that circumvent control technology designed to limit
interactive capacity to purchased levels.  This PTF may be a prerequisite
for future PTFs.  By applying this PTF you authorize and agree to the
foregoing.

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Code', the terms of which were provided in a printed document that was
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REGARDING THE PTF.





APAR Error Description / Circumvention

-----------------------------------------------
Unpredictable results in seemingly valid Telnet clients results
in dropped connections for no apparent valid reason.  The Telnet
server generates VLOG 0701 005D ( 0701005D ) when an errant
Telnet client is sending valid Telnet data streams, but appears
to be stuck in a loop or sending excessive streams of Telnet
commands to process.
An error in the way this is tracked by the system can cause the
value to go below zero.  This value was an unsigned integer, but
can "underflow" and take on a huge positive value on some
systems.

CORRECTION FOR APAR MA43764 :
-----------------------------
Timing between tasks involved is triggering run away Telnet
client detection.
Sensitivity to errant Telnet clients has been corrected to
handle task timing differences due to some system differences in
task processing while still protecting from errant Telnet
clients or Denial of Service (DoS) attacks.

CIRCUMVENTION FOR APAR MA43764 :
--------------------------------
None.


Activation Instructions


None.




Special Instructions


None.


Default Instructions

THIS PTF CAN BE APPLIED IMMEDIATE OR DELAYED.



Supersedes

PTF/FIX NO(S).  APAR TITLE LINE
--------------  ------------------------------------------------------------
   MF58108      F/TDTASKPAGEABLE-MSGMCH3402 MCH3402 ENTERING WRKSYSACT

Summary Information

System.............................. i
Models..............................
Release............................. V7R2M0
Licensed Program............... 5770999
APAR Fixed.......................... View details for APAR MA43764
Superseded by:...................... View fix details for PTF MF65458
Recompile........................... N
Library............................. QSYS
MRI Feature ........................ NONE
Cum Level........................... C5135720


System i Support

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Document information

More support for: i family

Software version: V7R2M0

Operating system(s): OS/400

Reference #: MF58590

Modified date: 06 November 2014