06. April 2017 · Comments Off on My latest article on Opensource.com – Introduction to the Domain Name System (DNS) · Categories: Information

My latest article, Introduction to the Domain Name System (DNS), has been posted on Opensource.com. This article talks about how name services work on both the client and server side, and lists some of the more common DNS records and their uses.

You may also be interested in some of my other articles about networking. The following list of articles are posted here, and may also be posted on Opensource.com.

The following articles are currently posted only on Opensource.com as of April 6, 2017.


09. February 2017 · Comments Off on I contributed to the 2016 Open Source Yearbook · Categories: Information

I contributed to the 2016 Open Source Yearbook. Download a copy at https://opensource.com/yearbook

There are a lot of really great articles this year. Enjoy!

Opensource.com Yearbook contributor

 


20. August 2016 · Comments Off on Unixmen: Five lesser known tools · Categories: Information, Linux, Open Source Software

I just read an interesting article on Unixmen.com about some useful tools that are not widely known. All are interesting, and some are CLI while others are for a GUI environment.

I particularly like two of the CLI tools, iptraf to monitor TCP/IP traffic on your computer, and lsblk to list information about all block devices attached to a computer; that would usually be disk drives of all types. I particularly like the tree view that lsblk displays of not just the drives, but also the partitions on the drives.

Note that iptraf is now iptraf-ng in some distributions.

The following output displays the list of disk drives, including DVD-ROM and USB drives, as well as the hard drives and their partitions.

Typical output from the lsblk command.

Typical output from the lsblk -a command. In this case several different disk types are shown.

The information provided by the lsblk -a command as shown above contains data about hard drives and removable USB hard drives.  It also shows removable CD-DVD/ROM drives, sr0 and sr1. Disks sda, sdb, and sdc are all three regular hard drives. The sdd and sde devices are attached USB removable drives.

The man page contains detailed assistance for getting the most out of this command.

See the article for more information about the other tools.

 


17. April 2016 · Comments Off on Cluster Failures · Categories: Information, Ruminations

No, “cluster failures” is not a euphemism for a problem encountered in the military service and widely known to be caused by officers with clusters on their shoulders. Nor does this page relate to failures of computing clusters.

This is about failures of independent computer systems and other devices that occur very close together in time. In some cases, the failures may also be of similar type such as a series hard drive or motherboard failures.

And recently I really have had a cluster of problems, some with computers and some not. Actually a cluster of clusters.

I have been repairing things for about sixty years. I started with TV’s, ours and our friends’ and neighbors’. Then I worked at a couple now defunct audio stores. I went on to fixing unit record equipment and computers for IBM. And when personal computers started hitting the streets, I started fixing those as well, both hardware and software.

Cluster failures are a real thing. When working at the audio stores, there would be days or weeks when the most common things people brought in for repair were receivers. And they were frequently similar failures such as the power output stage, or the IF stage. Other days it would be turntables with broken belts or component tuners that would not tune.

When I worked for IBM, there was one week when I fixed three punched card readers with nearly identical feed failures. And later, when working at the IBM PC National Support Center, there were days when most of the calls I fielded were memory (RAM) problems.

Sure, randomness abounds in the universe, including the failures of electronic and electromechanical devices. But sometimes that randomness expresses itself in clusters of failures.

The Church Cluster

It all began on Wednesday, September 9, when the server at my church began failing; really crashing hard. The computer we use as a firewall was also failing with intermittent crashes. In addition, one of the office computers froze up and the telephone system began failing.

It took a couple days for this to this play out and repair the computers. I don’t do the phone system, someone else does that.

The server, a donated Dell, was clearly having hard drive problems. There were specific errors on the console pointing to one of the hard drives. Murphy rules and there were no errors recorded in the logs, because the failing hard drive was where the logs were kept. So because I was not on site and the errors were displayed on the console, the person who rebooted for me could not read the errors as the display had timed out into power saving mode and pressing keys on the keyboard did not wake it.

In addition, the computer we use for a firewall was locked up so I rebooted it.

I took the server home to rebuild and by the next day had mostly completed that task, but not without discovering serious hardware issues. One of the hard drives had failed catastrophically. That was easy enough to fix. But in attempting to install a new operating system on the replacement hard drive, it became obvious that there were other problems as well. The motherboard was failing as well and it was impossible to boot or even to get through the BIOS POST. So I installed the spare Dell motherboard we kept on hand for just this event, and was able to proceed.

I was able to restore the data for our web site and email servers from the good and well-tested backups I designed. I was also able to restore the data for  the DHCP and name service (BIND) servers.

However, soon after I returned home with the server that I needed to rebuild, a different computer, the firewall began locking up more frequently. The office staff were still able to get out to the Internet so long as that firewall was working, but our web site and email was down because that is all housed on our server. Without the firewall, all external access was gone.

The next day, Thursday, I returned to the church and installed the rebuilt server, which worked fine.

However, after installing the server, the firewall started failing so frequently that I could not leave the premises before it would do so again. I made a quick trip back home to obtain a spare computer that had been given to me and had been used as a firewall itself. I installed it at the church, made a couple simple configuration changes, and the replacement firewall was up and running.

The Home Cluster

While all of that was going on at the church, my home network was also embroiled in a cluster of problems.

First, my own server started failing. One of the four 1GB memory DIMMs had failed. One of my workstations had a motherboard failure, and another system developed a defective power supply. A fan then failed on my server, and a video adapter failed on a different workstation. And, oh yes, a hard drive failed on my own workstation. And then a hard drive failed on my server.

And don’t get me started on my refrigerator and car.

What’s it all about, Alfie?

All of this took place within the space of a week, both at church and home. So it was a very trying week.

But what does it mean?

Well, as much as we like to assign meaning to things, there really is none. Things fail. Most of the time they work for years without a problem. Sometimes the failures are spread out evenly over time, or suddenly many things seem to fail at once.

So, sometimes when you get something fixed one day and it fails with another problem the next, that is just the randomness of the universe in which we live.

And now, weeks after the events described, all is well with the computers at church, at home, with my computers, car and fridge — until the next time.


11. January 2016 · Comments Off on Server migration complete · Categories: Information

I have completed the migration to the new server and have retired the old one. Everything seems to be working fine as of now, but please contact me if you notice any problems.

Thanks for your patience.


05. September 2015 · Comments Off on My “All Things Open” Talk · Categories: Information, News, Open Source Software

I will be presenting the talk, SystemV startup vs systemd at All Things Open on Monday, October 19th at 3:25pm. I do not yet know which room I will be in, but that should be available on the schedule when you get to the conference.

systemd is a controversial replacement for the init daemon and SystemV start scripts that is now used by many important distributions. My presentation will cover some of the differences between these two startup systems as well as some basic usage information needed by anyone getting started with systemd.

I hope to see you there.


21. June 2015 · Comments Off on David Both to present at All Things Open · Categories: Information, News

I will be presenting at least one talk at All Things Open this October 19th and 20th.

The one talk that has been accepted so far isSystemV startup vs systemd”. systemd is a controversial replacement for the init daemon and SystemV start scripts that is now used by many important distributions. My presentation will cover some of the differences between these two startup systems as well as some basic usage information needed by anyone getting started with systemd.

I will post more details about the specific date and time when I am notified of that information.

I hope to see you there.


11. June 2015 · Comments Off on Millennium Technology Consulting LLC Dissolved · Categories: Information

For a number of reasons, I am closing down the business entity known as Millennium Technology Consulting LLC effective immediately.

I will continue to maintain this DataBook® web site, where I post technical information for Linux system administrators and end users. If you are looking for help with Linux and other Free Open Source Software (FOSS), I post information here that – for me at least – was difficult to find or that took me a lot of time to discover through experimentation.

Because that business subsidised the operation of this web site, that source of financial support is no longer available. So, if you find this web site useful, I ask you to consider supporting it by donating so that it may continue to exist.

Thank you.


09. April 2014 · Comments Off on FAQs about the HeartBleed vulnerability · Categories: Information, Security

I received this on the CentOS list. You might find it helpful.


Since this is the first post about the openssl update, I want to answer
a couple questions here:

1. The first susceptible version of openssl in a CentOS release was
openssl-1.0.1e-15.el6, released on December 1, 2013.

2. The version of openssl that you should install to fix the issue is
openssl-1.0.1e-16.el6_5.7, released on April 8, 2014.

3. Versions of CentOS-6.5 openssl that were affected are:
openssl-1.0.1e-15.el6, openssl-1.0.1e-16.el6_5,
openssl-1.0.1e-16.el6_5.1, openssl-1.0.1e-16.el6_5.4.

4. Only CentOS-6.5 was affected. CentOS-6 at versions 6.4 or earlier
was not affected. No versions of CentOS-5 (or any other CentOS) were
affected.

Besides doing updates, things you should do include:

1. Besides doing the updates, you should replace any certificates using
SSL or TLS that are openssl based. This includes VPN, HTTPD, etc. See
http://heartbleed.com/ for more info on impacted keys.

2. See this page for figuring out which services you should restart
after applying updates .. or just reboot the machine which will restart
all services:

https://access.redhat.com/site/solutions/781793


26. October 2013 · Comments Off on Theory and Practice of Linux System Administration class, November 11 – 15 · Categories: Information, Linux, Training

For the last time this year, Millennium Technology Consulting LLC, will be running the highly reviewed class, Theory and Practice of Linux System Administration, the week of November 11 – 15.

About this Course

This course is intended for  junior and mid-level Linux Systems Administrators who wish to advance their knowledge, and administrators of other Unix versions or Windows who wish to become Linux System Administrators. This class is heavily oriented towards hands-on activities. At least half of the class time is allotted to lab projects.  Experienced Linux System Administrators also find this class valuable.Taken from my own experiences accumulated during more than 15 years of using Linux, and developed using my knowledge and experience as a course developer and trainer for both IBM and Red Hat, this class covers the practical aspects of Linux System Administration. It builds upon the foundation of the “Philosophy of Linux” in a way that helps the student understand how and why things are done as they are.

Our courses are always highly rated and well reviewed. Here are some comments from previous students taken directly from the course evaluation forms.

Course Description

The student will learn about the history of Linux and the philosophy of Linux and how it applies to the everyday tasks that she will be expected to perform. The student will install a current Fedora Linux system on common Intel hardware, using various installation options to customize the final result. The students will learn to use the command line interface (CLI) and many basic Linux commands along with the vi editor. More advanced commands such as sed and awk will be covered and combining all of these commands into short command line programs will be discussed and the student will have opportunity to use them in lab projects.

This course covers the Linux boot sequence and the traditional SystemV init scripts as well as an introduction to the new systemd daemon for startup and daemon management. The student will learn to manage users and software packages. Networking, security, processes, filesystems and Logical Volume Management will be covered in detail.

For complete details of this course see the Theory and Practice of Linux System Administration page.


02. September 2013 · Comments Off on Nine traits of the veteran Unix admin · Categories: Information, Linux, Unix

Here is a link to another article at InfoWorld that I really enjoyed. It is a couple years old but the content is timeless in the Unix and Linux worlds.

Nine traits of the veteran Unix admin


20. April 2013 · Comments Off on Giving up on nVidia · Categories: Information, Open Source Software

I have given up completely on nVidia graphics adapters.

Although they may work fairly well once configured, they require extra work to install non-free (as in speech) drivers that allow more complete use of the hardware’s functionality. Then, every time there is a kernel update, it is necessary to wait until the video drivers are updated or the X Window System won’t start.

The free (as in speech) nVidia drivers available from the Open Source community work fine for basic business tasks but do not provide OpenGL 3D support or graphics acceleration. In fact the nVidia proprietary drivers are incredibly slow and produce choppy animations. This problem has been getting worse in the last several iterations.

I have been switching all of my systems to ATI hardware and the Free Open Source drivers available for ATI provides complete support for 2D and 3D hardware acceleration as well as OpenGL animations and desktop effects. They are also significantly faster than the nVidia drivers.

The nVidia drivers I have found to be sadly lacking in overall support and functionality. This is a direct result of the fact that the advanced drivers are closed source and the Open Source nouvaeu driver developers have no access to the hardware documentation.

ATI, on the other hand, has provided much more cooperation in the way of documentation to the Open Source community and the ATI/Radeon drivers are far more capable than the nVidia drivers.

After recently spending a few days fighting to get the proprietary nVidia drivers running on my primary high-end workstation with a high-end nVidia adapter so I could use the OpenGL desktop effects, I gave up and purchased a new, high-end ATI/Radeon video adapter. After installing the ATI/Radeon hardware, I was immediately able to configure and use those effects.

The built-in ATI hardware also works fine on my Thinkpad laptop.

I have some nVidia graphics hardware you can have.


Once again I have changed the look of the DataBook.

This time I have chosen a theme that is simple and clean. It has a good number of options that I can use to modify the details of the theme so you may notice further changes as you return from time to time.

I particularly like this theme as it can display the date and time a document was published.

Please comment if you like or dislike this theme, and please let me know why. I do not want the theme to get in the way of your access to the data contained in the DataBook®.


23. February 2013 · Comments Off on More about Fedora 18 · Categories: Information, Linux, Reviews, Technical, Tips and Tricks

In my review of Fedora 18, I discussed my initial impressions of that newest release. Having now begun to install Fedora 18 on several more hosts in my constantly changing world I have found some interesting under the cover changes.

firewalld

A new firewall, firewalld, is now the default firewall for Fedora. Of course Fedora is the proving ground for many new things so, while this change was not particularly well documented, changes to Fedora in general should not be a surprise. The firewalld daemon is mentioned in three short paragraphs in the Fedora 18 release notes which only references the man pages for the new firewalld commands for further information, and once as being a new addition in the Technical Notes document. Both are available as PDF files from the Fedora Documentation Project.

The firewalld rules are quite complex compared to what I have been using with IPTables. This, and the fact that I am not yet familiar with the rule syntax or the overall structure of firewalld means that, for now at least, I need to revert to IPTables on my Fedora 18 hosts.

Reverting to IPTables

The good news is that the old IPTables firewall is still available until I can learn how to best create the firewall rules I need with firewalld. However it, too, has changed and some of the old IPTables rules, especially those using state related rule sets have been altered.

First, to convert back to IPTables, stop and disable the firewalld service and start and enable the iptables service.  Of course you must do this safely with your network disabled until you can get your new (old) firewall back in place. Then use the iptables-restore command to restore your old IPTables rules from the saved copy. You did save a backup copy of your IPTables firewall rules, right?

At this point, IPTables gives some errors indicating that one should use new connection tracking rules in lieu of the state-related rules. The best part is that IPTables is smart enough to give you the warning message and then translate the rules into connection tracking rules. At that point you can simply use the iptables-save command view the translated rules and redirect the output to /etc/sysconfig/iptables to save the translated rules.

So now I will take some time to learn this new firewall system while my IPTables firewall protects me.

Here is a link to the Fedora Project FirewallD documentation. http://fedoraproject.org/wiki/FirewallD


26. January 2013 · Comments Off on Fedora 18 Review · Categories: Information, Linux, Reviews

Fedora 18 was release about two weeks ago. I have just completed my review and you can Read it here.

 


Millennium Technology Consulting LLC has finalized its class schedules for the first quarter of 2013.

As you can see our newest class, Linux Servers and Advanced System Administration, has been added to the lineup after its successful test in December 2012.

Theory and Practice of Linux System Administration

This course is intended for trainee or  junior Linux Systems Administrators who wish to advance their knowledge, and administrators of other Unix versions or Windows who wish to become Linux System Administrators. This class is heavily oriented towards hands-on activities. At least half of the class time is allotted to lab projects. The class is based on Fedora because it is the upstream distribution for Red Hat Linux. Many of the more experienced Linux System Administrators who have taken this course also find it very valuable.

See the Theory and Practice of Linux System Administration page for a complete course description and prerequisites.

Class Schedule for Theory and Practice of Linux System Administration.

Dates Length Cost
January 14 – 18, 2013 5 Days $2495
February 4 – 8, 2013 5 Days $2495
March 11 – 15, 2013 5 Days $2495

 

Linux Servers and Advanced System Administration

This course is intended for experienced Linux System Administrators who wish to learn advanced troubleshooting techniques and server installation and configuration. By the end of the class each student will have a fully working Linux system with a firewall; a name server with forward and reverse zones; a DHCP server; an email server with integrated anti-spam; two working web sites with one a static HTML site and the other a complete WordPress site with a MySQL back end; A MailMan mailing list server; A VNC server; NFS and Samba shares. The student will also learn to build RPM packages.

See the Linux Servers and Advanced System Administration  page for a complete course description and prerequisites.

Dates Length Cost
January 21 – 25, 2013 5 Days $2995
February 18 – 22, 2013 5 Days $2995
March 25 – 29, 2013 5 Days $2995

 

Discounts

Discounts are available to members of the Triangle Linux Users Group (TriLUG) of $500 per class. You must have and show your TriLUG membership card to obtain this discount. This discount may be used in conjunction with other discount offers.

Custom Class Scheduling

Millennium Technology Consulting LLC can provide customized scheduling for classes. If you do not see a class scheduled within your desired time frame we can work with you to schedule one that meets your needs. We also offer on-site training at your location. Please contact us to schedule a class for you.


I just had an interesting experience while installing Fedora 16 on my primary workstation. It took me about 3 days and many attempted installations to figure this out. This is not a review, just a bit about my experience.

At first I wiped out my hard drive entirely since it has been several years since I did a really clean installation. That is, a complete wipe out of my hard drives—after first making certain that I had multiple good backups. Over time much cruft can accumulate from old application configuration and data and I wanted to get rid of everything except data I really wanted to keep.

Symptoms

The initial installation of Fedora 16 appeared to go well using the default choice of EXT4 for the filesystem type. After starting to make configuration changes and restoring a few directories in my non-root user home directory, KDE started crashing on a regular basis. It would indicate problems with Segment Faults. This is not good and can mean many bad things.

After installing several times with similar results, I decided to go back to Fedora 15. During the installation, I used EXT3. I had previously experienced an occasional problem with Fedora 15 while using EXT4, but nothing particularly repeatable. Many of the problems were during installation using EXT4 and I would get errors indicating that a specific package was not able to be installed. Looking at the log terminal (Ctrl-Alt-F3) most errors appeared to be on the DVD, but the DVD always tested as having no defects at the beginning of the installation.

Solution

My decision to use EXT3 was kind of on a whim, but the next install went without problems and I had no problems doing basic configuration. So I decided to reinstall Fedora 16 using EXT3 instead of EXT4 and have had no problems since. This is using the same physical hardware and the exact same partitions and logical volumes.

I think this indicates, at least to me, that there are still some bugs in EXT4. I have not however, seen this problem on some of my other systems. Perhaps it is the larger 1.5TB drives I am using on this system.

I hope this helps by preventing you from spending 3 days to discover and resolve this problem.


Thanks to WD “Bill” Loughman of Berkeley, California for sending me his downloads of some of the pages of the original DataBook for OS/2. Using that data, I have recreated the pages that he has saved. This is a great boon for anyone still using OS/2.

Unfortunately, much more data is still missing. If you, by any chance, have downloaded and saved any pages from the DataBook for OS/2, I would be very appreciative if you would zip them up and send them to me.

Not many people use OS/2 any more, but a bank I worked for recently just retired their last OS/2 ATM a few months ago. So it is still around.


I have one server for sale. See the For Sale page at Millennium Technology Consulting LLC for details.


This website will participate tomorrow, January 18, 2012, in protest of the SOPA law. That law would restrict the Internet freedoms of everyone for the somewhat questionable  financial benefit of a few media companies. In order to restrict alleged piracy, they would restrict the entire Internet. Web sites could be closed without any warning or even proof that they were in violation of any law—except the laws of greed.

Read about SOPA and the protest.

This bill will break the Internet as we know it.