OpenSSH ssh-rand-helper - insufficient data

Technote (troubleshooting)


Problem(Abstract)

FOTS1945 ssh-rand-helper child produced:insufficient data

Symptom

When using OpenSSH v1.2.0, intermittent timeouts may occur . The error messages include:

FOTS1842 problem renaming PRNG seedfile:from ...
(EDC5112I Resource:temporarily unavailable.
FOTS1945 ssh-rand-helper child produced:insufficient data
FOTS0841 Connection closed

Cause

Timeouts may occur when running ssh-rand-helper if the commands in the prng_cmds file cannot get enough CPU time to execute. This is typically a random event dependent on system workload.

Environment

OpenSSH 1.2

Diagnosing the problem

Refer to the error messages.

Resolving the problem

If the issue persists and you are running openSSH 1.2 you can modify the default 1 second time limit to allow for more time with the use of the _ZOS_SSH_PRNG_CMDS_TIMEOUT environment variable


The timeout value is in milliseconds and has a minimum value of 1 and a maximum value of
2147483646. The default value is 1000. (This equates to one second). Therefore, increase the amount above 1000.

This env var can be set as an export in the user's .profile. Another option is to place it in a data set so that all users can point to it with a STDENV DD statement in their batch job.

More information about the environment variable can be found in the manual,
IBM Ported Tools for z/OS: OpenSSH User's Guide, on page 9:
http://www-03.ibm.com/systems/resources/fotza501.pdf


Related information

OpenSSH User's Guide

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Document information


More support for:

z/OS family

Software version:

1.12, 1.13

Operating system(s):

z/OS

Reference #:

T1019539

Modified date:

2013-05-21

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