Tuesday, December 20, 2016



             is an operating system designed to be compatible with Microsoft Windows software.

We use iso file from http://downloads.sourceforge.net/reactos/ReactOS-0.4.3-iso.zip

After download we create virtual machine and start to install:

Now we can use ReactOS J

Monday, December 5, 2016


this is first day of:



MikeOS is an operating system for x86 PCs, written in assembly language. It is a learning tool to show how simple 16-bit, real-mode OSes work, with well-commented code and extensive documentation. Features:
A text-mode dialog and menu-driven interface
Boots from a floppy disk, CD-ROM or USB key
Over 60 system calls for use by third-party programs
File manager, text editor, image viewer, games...
Includes a BASIC interpreter with 46 instructions
PC speaker sound and serial terminal connectionThe code is completely open source (under a BSD-like license), and is written by Mike Saunders and other developers.
Source: http://mikeos.sourceforge.net/

To run with VM Player:

- Download zip file from http://mikeos.sourceforge.net/#downloads
- Create new machine with option “Other”
 After all we can use MikeOS  J

Tuesday, September 27, 2016

Rbash - way to restrict what users can do on your Linux systems.

Rbash - limited shell

If Bash is started with the name rbash, or the --restricted or -r option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. A restricted shell behaves identically to bash with the exception that the following are disallowed or not performed:

  • Changing directories with the cd builtin.
  • Setting or unsetting the values of the SHELLPATHENV, or BASH_ENV variables.
  • Specifying command names containing slashes.
  • Specifying a filename containing a slash as an argument to the . builtin command.
  • Specifying a filename containing a slash as an argument to the -p option to the hash builtin command.
  • Importing function definitions from the shell environment at startup.
  • Parsing the value of SHELLOPTS from the shell environment at startup.
  • Redirecting output using the ‘>’, ‘>|’, ‘<>’, ‘>&’, ‘&>’, and ‘>>’ redirection operators.
  • Using the exec builtin to replace the shell with another command.
  • Adding or deleting builtin commands with the -f and -d options to the enable builtin.
  • Using the enable builtin command to enable disabled shell builtins.
  • Specifying the -p option to the command builtin.
  • Turning off restricted mode with ‘set +r’ or ‘set +o restricted’.

These restrictions are enforced after any startup files are read.


usermod -s /bin/rbash user
grep user /etc/passwd

[user@peg ~]$ cd

bash: cd: restricted

[user@peg ~]$ ls t
[user@peg ~]$ cat t > test

bash: test: restricted: cannot redirect output

[user@peg ~]$ file about.sh
about.sh: POSIX shell script text executable
[user@peg ~]$ ./about.sh

bash: ./about.sh: restricted: cannot specify `/' in command names


Wednesday, July 27, 2016

Quick UDP Internet Connections

What is QUIC?

QUIC (Quick UDP Internet Connections) is a new transport protocol for the internet, developed by Google.

QUIC solves a number of transport-layer and application-layer problems experienced by modern web applications, while requiring little or no change from application writers. QUIC is very similar to TCP+TLS+HTTP2, but implemented on top of UDP. Having QUIC as a self-contained protocol allows innovations which aren’t possible with existing protocols as they are hampered by legacy clients and middleboxes.

Key advantages of QUIC over TCP+TLS+HTTP2 include:
  • Connection establishment latency
  • Improved congestion control
  • Multiplexing without head-of-line blocking
  • Forward error correction
  • Connection migration

more / source:

Evolution of Unix and Unix-like systems

The ‘Unix philosophy’ originated with Ken Thompson's early meditations on how to design a small but capable operating system with a clean service interface. It grew as the Unix culture learned things about how to get maximum leverage out of Thompson's design. It absorbed lessons from many sources along the way.

more / source:

Monday, July 11, 2016

Directory contents -

 Unix-like operating systems.

Directory structure and directory contents in Unix-like operating systems
- image from http://pclosmag.com/

Tuesday, June 28, 2016

What is the most important Linux security technology?

According to the article by linuxsecurity.com the most important Linux security technology is SELinux. Whether you agree ?

read more here:

Sunday, June 26, 2016




via: http://www.cyberciti.biz/tips/linux-kernel-history-and-distribution-time-line.html


HelenOS HelenOS is a portable microkernel-based multiserver operating system designed and implemented from scratch. It decomposes k...