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HowTo: Use OpenBSD In the Corporate Environment

OpenBSD has a reputation for high security and difficult operating systems for new user. But, some orginsations are using OpenBSD for everything including firewall, servers and desktop computers. This is quite impressive, from the article:

So our paid job is hacking on and deploying, maintaining, supporting... OpenBSD installations. We are also required to hack on things that can be merged back into OpenBSD itself and when it's not possible, then we change what we did so that it can be. Of course some developments are very specific to what we do and have no place in the project's CVS tree.

So, amongst other services, we set up and maintain several 100% OpenBSD-based infrastructures (going from the entry site firewall to the secretary's workstation) and this is what I'm going to talk about here.

As a side note, it is important to know that we are working exclusively for Fortune 500 companies (each operating in totally different and unrelated sectors).

Read more: A Puffy in the corporate aquarium.

Linux Condor security and bug fix update

Condor is a specialized workload management system for compute-intensive jobs. It provides a job queuing mechanism, scheduling policy, priority scheme, and resource monitoring and management.

A flaw was found in the way Condor interpreted wildcards in authorization lists. Certain authorization lists using wildcards in DENY rules, such as DENY_WRITE or HOSTDENY_WRITE, that conflict with the definitions in ALLOW rules, could permit authenticated remote users to submit computation jobs,
even when such access should have been denied. (CVE-2008-3424)

How do I fix this bug in Condor Software?

Type the following command to fix this bug
# up2date -u
If you are using Red Hat Enterprise MRG 1, enter:
# yum update

Bug Fixed in this update

* the /etc/condor/condor_config file started with "What machine is your
central manager?". The following line was blank, instead of having the
"CONDOR_HOST" option, causing confusion. The "What machine..." text is now

* condor_config.local defined "LOCK = /tmp/[lock file]". This is no longer
explicitly defined; however, lock files may be in "/tmp/", and could be
removed by tmpwatch. A "LOCK_FILE_UPDATE_INTERVAL" option, which defaults
to eight hours, has been added. This updates the timestamps on lock files,
preventing them from being removed by tools such as tmpwatch.

* when a "SCHEDD_NAME" name in condor_config ended with an "@", the
system's hostname was appended. For example, if "SCHEDD_NAME = test@" was
configured, "condor_q -name test@" failed with an "Collector has no record
of schedd/submitter" error. Now, the hostname is not appended when a name
ends with an "@". In High Availability (HA) Schedd deployments, this allows
a name to be shared by multiple Schedds.

* when too few arguments were passed to "condor_qedit", such as
"condor_qedit -constraint TRUE", a segfault occurred. Better argument
handling has been added to resolve this.

* due to missing common_createddl.sql and pgsql_createddl.sql files,
it was not possible to use Quill. Now, these files are included in

* "condor_submit -dump ad [file-name]" caused a segfault if the [file-name]
job contained "universe = grid".

* previously, a condor user and group were created if they did not exist,
without specifying a specific UID and GID. Now, UID and GID 64 are used.
The effect of this change is non-existent if upgrading the condor packages.
If an existing condor user and group are manually changed, problems with
file ownership will occur.

Configuration changes (from the Condor release notes - see link below):

* a new CKPT_SERVER_CHECK_PARENT_INTERVAL variable sets the time interval
between a checkpoint server checking if its parent is running. If the
parent server has died, the checkpoint server is shut down.

* a new CKPT_PROBE variable to define an executable for the helper process
Condor uses for information about the CheckpointPlatform attribute.

* STARTER_UPLOAD_TIMEOUT now defaults to 300 seconds.

* new variables (booleans) PREEMPTION_REQUIREMENTS_STABLE and
PREEMPTION_RANK_STABLE, configure whether attributes used in

default value of 5, defines the number of simultaneous WS destroy commands
that can be sent to a server for type gt4 grid universe jobs.

* now, VALID_SPOOL_FILES automatically includes the "SCHEDD.lock" lock file
for condor_schedd HA failover.

* the default value for SEC_DEFAULT_SESSION_DURATION has been changed from
8640000 seconds (100 days) to 86400 seconds (one day).

Important: these updated packages upgrade Condor to version 7.0.4. For a
full list of changes, refer to the Condor release notes:

condor users should upgrade to these updated packages, which resolve these

Getting Yesterdays or Tomorrows Day With Bash Shell Date Command

When invoked without arguments, the date command displays the current date and time. Depending on the options specified, date will set the date and time or print it in a user defined way. I've seen many sysadmin writing perl scripts for calculating relative date such as yesterdays or tomorrows day. You can use GNU date command, which is designed to handle relative date calculation such as:

  • 1 Year
  • 2 Days
  • 2 Days ago
  • 5 Years

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List of open source cluster management systems

M. Shuaib Khan has published a list of open-source cluster management systems.

Personally, I had used openMosix and Red Hat Cluster software (which is also based upon open source software funded by Red Hat).

From the article: In computing world, the term "cluster" refers to a group of independent computers combined through software and networking, which is often used to run highly compute-intensive jobs. With a cluster, you can build a high-speed supercomputer out of hundreds or even thousands of relatively low-speed systems. Cluster management software offers an easy-to-use interface for managing clusters, and automates the process of queuing jobs, matching the requirements of a job and the resources available to the cluster, and migrating jobs across the cluster:

=> openMosix
=> Kerrighed
=> OpenSSI
=> Gluster

Read this article it offers feature, cons and pros of each solution.

Howto: Shutdown Linux Box Automatically

You may wonder - why should I shutdown the Linux box automatically? It depends upon your situation. For example, you are downloading couple of tar balls and you want to go home early. You can schedule a job to shutdown Linux after downloading is completed. Linux/UNIX/BSD/OS X comes with at and cron commands to automate task. Almost all common task can be automated using at command.
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