Fixing dbg installation problem

I needed to install gdb quickly on my CentOS 7 VM box, but it failed. yum command could not find appropriate repository for download and installation. The same I had before with different application. Of course it was possible to perform all installation steps manually: find location of appropriate rpm or source files and rebuild,… Read More »

Shaileshkumar scheme

Probably it happened to everyone at least once, you want to google or to open Facebook page and you don’t enter the URL correctly in the address bar and you are redirected to a site that warns you that your computer is completely infected with all kinds of viruses, and will die soon or all… Read More »

Dive into WHOIS protocol

WHOIS is a TCP-based query/response protocol which is used to get information about registered domain names, domain name servers, registrar, creation and paid till date. Also it may contain data about domain owner and/or owner’s contact requisites. Default tcp port of WHOIS protocol is 43. The WHOIS client send a text request to the WHOIS… Read More »

Private and Public keys generation and usage for CentOS

Public and private key pair is alternative way of server logging using Secure Shell (SSH) protocol. It gives possibility to avoid user name and password prompts so could be faster and more comfortable. Besides both keys represent two long string of characters, so eventually it is more difficult to crack. There are a lot of… Read More »

Simple example of SSH tunneling

SSH tunneling is a technique to transfer arbitrary networking data using an encrypted SSH connection. It can be used to add encryption to not secure protocols such as HTTP and to bypassing firewalls. It is also named as port forwarding, there is a post related to C# implementation of SSH port forwarding. Here is presented… Read More »

MSDOS debugger

If you are not familiar how to enable old legacy MSDOS application capabilities on modern Windows OS, it is good to start with “WoW. 16-bit supplication on 32-bit Windows” article. The MS-DOS debugger is portable command line-oriented debugger in operating systems such as MS-DOS and OS/2, Windows (16-bit/32-bit versions only). It is started by DEBUG… Read More »

WoW. 16-bit application on 32-bit Windows.

There was time when PC used 16-bit microprocessors such as 8086 and 80286. The first 32-bit Windows NT operating system had NTVDM (NT Vistual DOS Machine) component that allowed execution of 16-bit Windows and 16-bit / 32-bit DOS applications. The latest 32-bit Windows operating systems does not support NTVDM by default, it should be enabled.… Read More »

VirtualBix bidirectional clipboard between host and guest

After installation virtual machine in Oracle VirtualBox clipboard between host and guest machines does not work. It is necessary to do some manipulation to start Copy and Paste operation working. Below is example how organize bidirectional clipboard between Windows host and CentOS guest. In Oracle VM VirtualBox Manager right click on your VM, select Setting,… Read More »

snmpget in C#

SNMP (simple network management protocol) is the way to discover information about remote device or to monitor such device using agentless technique. The agentless approach means that no additional custom spy software is installed on target device. Anyware snmp or WMI are detective features, but usually they are part of operating system. Here is example… Read More »

Linux C error handling, errno and perror

If you have Java or .Net programming background you used to be familiar with exception which generated in runtime if something is going wrong with code execution. Linux C does not provide direct support to runtime error handling or exception handling. Usually code developer has to check return values from the functions. Generally C function… Read More »