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HP Color LaserJet Pro Multifunction M479fdn Laser Printer

My new M479nfd printer, scanner, fax

Click to get this printer on Amazon.com where I'm an affiliate.

Not too long ago, I ordered a new color drump for my old printer and replaced it. Not very long after that the print simply decided to not print at all anymore. Literally, it would pass the page through just fine but it had nothing on the page. I know it was working since it was printinA picture of my old dinosaur printer, also from HP (an L2550 color laser printer)g just fine the day before and there was still plenty of black ink (it would have had the light on if the black was not enough.)

I'm thinking that may have been a ploy by the manufacturer to push me to buy a new printer...

In any event, ...

Linux to the rescue!

Xtra-PC, a complete ready to go OS on a thumb drive

Doug and I have always thought that Linux would become the primary OS of today.

We've seen it go up and down, but now it's really becoming powerful, between OpenOffice, Chrome, The Gimp, Krita, Audacity, and many other tools, you can do so much that it more and more renders the expense of running MS-Windows less and less viable for most.

Now there is this new company offering a thumb drive with an optimized version of Linux called Xtra-PC which boots really fast and offers all the basics that one needs to run a computer. There is nothing to install, the OS will automatically detect ...

Safely Processing a Queue of Jobs

What is a Queue

In software a queue is a container which is used to add items on one side and remove them on the other in a very efficient manner.

Sorted Queues

When used by a Journal, a queue is often going to support some kind of sorted order. Some jobs are more important than others and these should be built sooner. In other words, we give those jobs a higher priority and we sort the queue by priority first then using the time at which the job gets inserted.

Note that the C++ std::queue and std::unque containers do not offer anyway to support a priority. Instead you have to use ...

Docker, an advanced chroot utility


Chasm—just like a Docker creates a chasm between two sets of software

SECURITY WARNING

Before installing Docker and containers with services on your Linux system, make sure to read and understand the risks as mentioned on this Docker and iptables page. Especially, Docker will make all your containers visible to the entire world through your Internet connection. This is great if you want to indeed share that service with the rest of the world, it's very dangerous if you are working on that container service since it could have security issues that need patching and such. Docker documents a way to prevent that behavior by adding the following rule to your firewall:

iptables -I DOCKER-USER -i eth0 ! -s 192.168.1.0/24 -j DROP

This means that unless the IP address matches 192.168.1.0/24, the access is refused. The `eth0` interface name should be replaced with the interface name you use as the external ethernet connection. During development, you should always have such a rule.

That has not worked at all for me because my local network includes many other computers on my LAN and this rule blocks them all. So really not a useful idea.

Instead, I created my own entries based on some other characteristics. That includes the following lines in my firewall file:

*filter
:DOCKER-USER - [0:0]

-A DOCKER-USER -j early_forward
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 80 --ctdir ORIGINAL -j DROP
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 8080 --ctdir ORIGINAL -j DROP
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 8081 --ctdir ORIGINAL -j DROP

My early_forward allows my LAN to continue to work. These are my firewall rules that allow my LAN computers to have their traffic forwarded as expected.

Then I have three rules that block port 80, 8080, and 8081 from Docker.

Docker will add new rules that will appear after (albeit not within the DOCKER-USER list) and will open ports for whatever necessary service you install in your Dockers.

Note that the only ports you have to block are ports that Docker will share and that you have otherwise open on your main server. If Docker opens port 5000 and your firewall does not allow connections to port 5000 from the outside, then you're already safe. On my end I have Apache running so as a result I block quite usual HTTP ports from Docker.

Docker

As we are helping various customers, we encounter new technologies.

In the old days, we used chroot to create a separate environment where you could have your own installation and prevent the software from within that environment access to everything on your computer. This is particularly useful for publicly facing services liek Apache, Bind, etc.

Help with version 0.1.7 of Zipios (CVE-2019-13453)

Here is yet another example of why opensource is a really good way of getting things fixed.

Assuming you have a project that is getting used by many, you are likely to see people post issues about bugs and possible enhancements. Your software is even very likely to get improved on its own by enthousiast users. On Github, for example, it is very easy to fork a project (make a copy) and then work on your version of the software. You can then offer a fix to the main authors of the project with a near one to one copy of the project.

In our case, a security professional, Mike Salvatore, was asked ...

Best C++ Books

Once in a while someone will ask me which book is best to start learning programming. The fact is that I do not know because I'm already an advanced programmer and it's rather difficult for me to get back to the basics (it feels like a waste of my time, sorry...)

That being said, at Made to Order Software, we've mainly been a C++ shop. We also do a lot of C, PHP, JavaScript and touch many other languages as required by the tasks we perform (bash, cmake, perl, C#, Java, etc.)

That being said, I wanted to underline some of the best C++ books available today. Especially, in the last ...

Brief Overview of CRISC Certification Exam

The CRISC, also known as Certified in Risk and Information Systems Control, is a vendor-neutral certification that validates a professional’s knowledge and experience in the fields of information system control & risk management. The certificate is developed and administered by ISACA and designed for the individuals who work with organizations in mitigating business risks and implement information system controls.

Organizations in today’s world must consistently enhance their infrastructure so that they can survive and thrive in today’s competitive environment. It is a ...

Deleting a (Duplicate) Retweet from your Twitter Feed

Double Retweeting and How to Avoid Over-Duplication

I have seen many people retweeting like crazy and I've noticed that once in a while these people have been retweeting the exact same tweet more than once.

I'm pretty sure that in most cases these people ignore the fact. Personally I find their twitter feed annoying because of that. Retweeting is totally okay, it's sharing what others have tweeted and there is nothing wrong with it. However, seeing the exact same tweet 2, 3, 4, or even 5 times pretty much in a row is rather bad taste. I understand that this very tweet is super ...

Getting Rid of Deactivated Facebook Friends

Last updated in Dec 31, 2017 as many things have changed.
Not only that, I also noticed that "dead" accounts are not always really dead.
Read below to learn more.

I was slowly nearing 5,000 friends when all of a sudden I had 5,089!

Wondering what was happening, a post on the Blackhat World forum caught my eye as someone mentioned the fact that he had 5,700 friends. The answer was that deactivated friends do count against your 5,000 friends limit. They are counted as part of your friends even though they do not have an account anymore and they don't get automatically removed ...

The set_fax_id() function PHP e-Fax must be given unique IDs, each time.

Fax button on an old type of fax machine

The PHP eFax system uses a class that ease the communication between your software and eFax. The developer system is not too complicated, but there are tricks to it and the class hides most of them.

Today a customer contacted us as they just purchased a copy of our PHP library and had problems sending faxes. The fact is that they used the set_fax_id() function with a hard coded string. Imagine doing something like:

$efax->set_fax_id("Test Fax");

This looks pretty good, only after the second time the sending of the fax will fail because eFax considers that it was already ...