Duplicate V3 extension in a X.509 certificate

Recently, I got a report that one application can’t connect to the Exchange server. The error message was:

Exchange server error: The request failed. javax.net.ssl.SSLProtocolException: java.io.IOException: Duplicate extensions not allowed.

The first Google search revealed to me that this error message is related to the error inside the SSL certificate and the java based library can’t override such situation. Continue reading


Renaming remote Windows computer using the command line

Whether you need to rename a local or remote Windows computer, you can perform that task in multiple ways. We all know how to do that using the GUI. Here is the mighty Jedi trick to do the same task from the command line. And from your workstation, too. Continue reading

Advanced disk repairing option in Windows 8 and later

A few months ago, I encountered a problem with one USB hard disk. Whenever it was attached to any PC, Windows will prompt that volume has errors. As always, we click on Scan and Fix option expecting that that would do the job.

This disk was one of a kind and now you can read about it. I tried a few times to repair it. Every time, the disk check passed and all was fine, until I again needed to reconnect the disk. Then the story repeated. Continue reading

Tiny Core Linux on a USB stick

The Linux live CD or USB stick is not hot news. But, having the full installation running from a USB flash drive that acts like a hard drive is the difference. All you need is any PC with the boot from USB capability and 128+ Megabytes of RAM.

Are you interested? Continue reading

Configuring a FloppyFW router

I successfully built a new VM that will serve as the ADSL router in my virtual lab. As the next step, I needed to configure it with specific parameters for my virtual lab. I will guide you through the configuration process for this scenario.

The good news is that the whole configuration for FloppyFW is stored in only one single file named config. This file is placed in the root of the floppy image file. Continue reading

A new “ADSL” router in my virtual lab

I keep looking for ways to improve my virtual lab and made it as realistic as possible. Although using Mikrotik routers is enough to build a large infrastructure, it’s not completely accurate with the real world experience – Mikrotik routers always work.

In the real world, we often need to connect a Mikrotik router either directly to other types of devices or even behind an exotic grandma’s home appliance. On the other hand, this is the lab and I don’t need any fancy features in such software. I want to save every megabyte of RAM or disk space on my laptop.

My search was fruitful and I found the perfect candidate – FloppyFW. This is the fully functional Linux-based router/firewall that can fit on a single 1.44” floppy disk.

Continue reading