HTTP for IPv6 from client side

IPv6 works in the same way as IPv4 address, however IPv6 addresses must be enclosed in square brackets. It is required to avoid conflict with colon character in protocol specification: http:, https:, ftp:. To test IPv6 installed Apache server on Ubuntu device and enable IPv6. The IPv6 of my Ubuntu device is “2002:ac7:fa01:c71e:250:56ff:fe98:bebd”. First I… Read More »

Python deals the cards

About 10 years ago I applied to software developer position and received the following coding exercise: Using Java/Python, please design and implement the classes for a card game (pick any game, Poker for example), which uses an ordered deck of cards, containing 52 cards divided in 13 ranks (A, 2, 3, 4, 5, 6, 7,… Read More »

Unix or Epoch time turned 50 and Y2K38 problem is coming

The Unix time was born January First 1970 exactly at 12 AM with no minutes and seconds. Its age already exceeds 1 billion and 600 millions seconds or 0x5F5E1000 in hex value, so far it is good for 32-bit positive signed integer, but until Tuesday, January 19, 2038 when this number becomes 32-bit negative integer.… Read More »

Mac OSX CPU Information. Terminal and Programmatically.

Apple Silicon CPU is coming. As announced x86_64 application will be able to run on ARM Apple Silicon using Rosetta translation, however there is some exclusion for example Rosetta doesn’t translate Kernel extensions. I checked this Saturday at Costco, they still sell Intel based Mac only. I opened terminal on demo Macs and executed sysctl… Read More »

Valgrind Testing of non Virtual Destructor

What is the purpose of Virtual Destructor? Sometime this question is asked on job interview. The main purpose of virtual destructor is to keep appropriate clean-up sequence when object is disposed. Deleting a derived class object which is casted to pointer of base class may be result of memory leak if base class destructor is… Read More »

HTML Obfuscation

Experimenting recently with obfuscation I decided to do some muddling code myself. I chose to change HTML page to make it difficult for understanding. For this purpose I created small encoder which coverts ASCII string to HTML entity presenting. This encoder is implemented in JavaScript and it is here. Then I using this encoder I… Read More »

Installing Powershell and Invoke-Obfuscation on CentOS 8

This article shows how to obfuscate PowerShell command or script for free using Invoke-Obfuscation. We will obfuscate powershell command on Linux CentOS machine and execute obfuscated command on Windows PC. Invoke-Obfuscation runs under powershell and because Microsoft powershell is cross-platform tool and available for many not Windows platforms this obfuscator could be also used anywhere.… Read More »

PID File and Process Name

PID file is small file that contains process identification number usually for daemon processes. Typically pid file location is /var/run directory or sub-directories of /var/run. In new Linux versions /var/run is symbolic link to /run directory. The PID file is created when daemon service is started and deleted when the service stops. If daemon process… Read More »

Peculiar Features of SSH Daemon for CentOS 8

After installation of new CentOS 8 on VM device I was surprised to find that secure shell daemon is configured differently than I saw in previous versions of CentOS devices. CentOS 8 SSH Daemon does not use definition of Ciphers, KexAlgorithms, GSSAPIKexAlgorithms and MACs from /etc/ssh/sshd_config file anymore as for example CentOS 7 does, but… Read More »

Favicon for and other WordPress websites

Favicon (favorite icon) is small image that appears with the website title on the browser tab. The icon increases site’s personality and makes it more attractive. When Web browser client downloads favicon files it should be recognized by the web browser as URL icon to be displayed appropriately. Normally browser is informed about favicon through… Read More »