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Finding Prime Numbers

April 22, 2016 – 2:09 pm

I have no intention of competing with GIMPS. To me this is a fun scripting exercise that may produce useful results beyond this initial application. Our goal is to take a bunch of integers and …

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Networking

Unix and Linux network configuration. Multiple network interfaces. Bridged NICs. High-availability network configurations.

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Reviews of latest Unix and Linux software. Helpful tips for application support admins. Automating application support.

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Disk partitioning, filesystems, directories, and files. Volume management, logical volumes, HA filesystems. Backups and disaster recovery.

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Distributed server monitoring. Server performance and capacity planning. Monitoring applications, network status and user activity.

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Cool Unix shell commands and options. Command-line tools and application. Things every Unix sysadmin needs to know.

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Monitoring NetBackup Daemons

April 27, 2016 – 9:25 pm
tape dlt backup

Here’s an example of a script you can use to monitor NetBackup server daemons in a Linux environment. The main difficulty with keeping track of these services is that there are so many of them. What makes NetBackup reliable and rich in features is the modular nature of its design. For the same reason, a NetBackup server may need to run upwards of two dozen service daemons – often multiple instances of each. Read the full story »

Using JTR to Crack Office Documents

April 22, 2016 – 5:35 pm
Macro computer screen shot with binary code and password tex, great concept for computer, technology  and online security.

John the Ripper is a free multi-platform password-cracking software. This article is not intended to be a comprehensive guide to jtr, rather a quick how-to. Starting with version 1.7.9, jumbo patch 6, jtr supports password …

Counting Beer Calories

February 24, 2016 – 10:58 pm
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Calories in beer come mainly from alcohol, unfermented sugar, and residual yeast. You’ve heard of the beer belly, but there’s nothing special about beer calories. A bottle of Heineken (150 calories) won’t make you any …

Monitoring Application Network Connections

February 11, 2016 – 3:12 pm
network switch

A Java application on one of my servers has been causing problems by opening up too many network connections and now closing them quickly enough. I needed to be notified when the number of connections …

Run Cron Jobs at Arbitrary Intervals

January 27, 2016 – 10:24 am
time clock watch

Current versions of cron support sophisticated syntax making creating weird schedules a breeze. With older versions of cron you normally had to schedule multiple jobs to fill every time slot in a complex schedule. The …

Diff on Output of Remote Commands

January 25, 2016 – 1:47 pm
shell

Let’s say you run the same command on two remote servers and you want to compare the output. Here’s a quick example:

Show NIC Bandwidth Utilization

January 15, 2016 – 12:43 am
network switch

Just a quick script that will measure bandwidth utilization in KB/s for all NICs on your server over the specified period of time. You can call the script with an optional time wait parameter in seconds.

Find + Rsync + Xargs

December 22, 2015 – 11:09 am
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Just some quick syntax for running multiple rsync threads in parallel using find and xargs. In many cases (especially if NFS is involved)  this can greatly speed up the copy operation.

Taking Linux Temperature

December 14, 2015 – 12:21 am
termometer_001

Just some notes on setting up temperature monitoring and alerting on CentOS/RHEL running on HP ProLiant. The first step is to install lm_sensors:

Bash and Expect Snippets

November 25, 2015 – 1:12 pm
shell

A small collection of maybe helpful examples of how to use expect with Bash. This is a very useful tool, especially when writing a better script is just too much work, but the funky syntax …

Deleting Lots of Files Quickly

November 17, 2015 – 9:03 am
machine-gun-001

I am not talking about hundreds or thousands of files. I am talking about hundreds of thousands. The usual “/bin/rm -rf *” may work, but will take a while. Or it may fail with the …

When Was that Server Built?

November 11, 2015 – 11:49 am
shell

Just a quick note on how to (sort of) figure out when a server first came online. This can be useful to various folks in your bean-counting department working on maintenance contract renewals and whatnot. …

Testing Email Server Response

November 7, 2015 – 5:37 pm
colorful shells

A little while ago I ran into a situation when connections to the relay email server would occasionally time out. The issue seemed sporadic resulting in a controversy regarding its source. The perimeter email server …

Tuesday Morning Rant

October 27, 2015 – 11:27 am
centos_linux_0003

So I just got around to installing CentOS 7. What a pile of shit with bugs all over it. The installation GUI completely messed up network configuration. On the first try, the network config I …

Oracle Sun SPARC Server Quick Configuration

October 20, 2015 – 6:03 pm
sun_solaris_0003

In the following example we’re using a SPARC T4-2. These systems ship from the manufacturer with pre-installed Solaris 11. After the system has been racked and connected to primary and ILO networks, the first step is to …

Detecting Sun ILOM with NMap

October 13, 2015 – 10:57 am
sun_solaris_0002

This is an oddball tech note: how to detect Sun ILOM interfaces on the network using nmap. I needed to connect to one of the Sun boxes that dropped off the network, but couldn’t remember …

Upping the Soft nproc Limit

October 5, 2015 – 11:12 am
overloaded_0004

This is just a quick note to myself about increasing the “soft nproc” value. On one of the RHEL 6 Tomcat servers I got the following error when trying to “su – tomcat”:

Hold Off on iOS 9 iPhone Upgrade

September 21, 2015 – 2:16 pm
apple_0006

If you haven’t updated your iPhone 6/6 Plus to the recently-released iOS 9, I’d suggest you hold off for a few weeks. Several bugs – including a significant security hole – have surfaced that will …

Removing Metadata from Images

September 8, 2015 – 12:09 pm
binoculars watch security rifle gun

Phones and cameras record a surprising amount of personally-sensitive information with the photos they create. This data includes timestamps, GPS coordinates, software used to process the images and lots of other details you may not …

Reduce SNMPd Logging Level

September 8, 2015 – 11:01 am
overloaded_0003

By default, (on RHEL/CentOS, at least) snmpd will log all connection attempts, which can turn your /var/log/messages into a giant mess, looking something like this…

Arthemia jCarousel Number of Posts

September 4, 2015 – 3:45 am
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This is primarily just a note to myself on how to change the number of visible items in the jCarousel implementation for the WordPress Arthemia theme. Recently I finally updated to the current version and …

Tuesday Night Rant: LED Light Bulbs

September 1, 2015 – 9:51 pm
Row of light bulbs

An off-topic for sure, but after a brief conversation about LED bulbs with a friend – an electrician – I found I had more arguments then I was willing to spill on Facebook. I am …

Collectl & Colplot Sytem Performance Analysis Tools

August 26, 2015 – 11:17 am
linux_penguin_0002

It is not often that I run into Unix performance analysis tool that, a), I haven’t seen before and, b), is worth my attention. Collectl is both. It is a very useful combination of iostat, …