System – Page 3 – POFTUT

How To Generate Random Numbers with rand() and srand() Functions in C and C++?

C and C++ programming languages provide rand() and srand() functions in order to create random numbers. Random numbers can be used for security, lottery, etc. In this tutorial, we will learn how to use a random number generating functions rand() and srand() with their attributes and specialties. Random Numbers Random numbers are sequential numbers that are different … Read more

What Is MD5 Hash Checksum? How To Create and Validate MD5?

MD5 is a checksum or hash calculation method for files. MD5 checksum consists of 128-bit value which is generally expressed as the hexadecimal format with which consist of 32 characters. MD5 Attributes MD5 is a cryptography algorithm which provides some attributes which make it useful for different cases like security, operation etc. Here is the list … Read more

Rpm, Yum, Dnf “NOKEY” Public Key Check Error and Solution

Rpm is very popular and secure package management format and application. Recent version of the rpm and yum command uses Public Key Check in order to make installation more secure. This is done by checking integrity of the rpm package. NOKEY Error For RPM Package We may see the error during a package installation with … Read more

What is Zenmap and How To Download, Install, and Use In Windows, Linux?

Zenmap is a free and open-source GUI designed to be used with Nmap. Zenmap is a multiplatform tool that supports Linux, Ubuntu, Mint, Kali, Fedora, CentOS,.., Windows, Mac OS X, BSD, etc. . .nmap  is a very powerful tool for network scanning and vulnerability discovery but it is completely command-line based. Zenmap can be used by … Read more

How To Install and Use ClamAV Antivirus Software In Linux, Ubuntu, Debian, Mint, Kali, Fedora, CentOS, RHEL

Linux distributions like Ubuntu, Debian, Mint, Kali, Fedora, CentOs, RHEL are considered as virus free and advertised by open source advocates. This is a bit false but generally true assumption. Linux environment have very little viruses against Windows and MacOS. But Linux environment is not fully secure against. In this tutorial we will examine how … Read more

OpenPGP Mail Encryption and Related Tools For Linux, Windows

OpenPGP is a email encryption standard used by a lot of people. This standard is defined by OpenPGP Working Group of the Internet Engineering Task Force (IETF). The standard is proposed with RFC 4880 . The OpenPGP is derived from PGP software which is created by Phil Zimmermann. OpenPGP Windows Tools Gpg4win Gpg4win is popular … Read more

What Is Nagios?

What Is Nagios?

Nagios is an open-source system, network, application monitoring system. Nagios is designed to be run on the Linux operating system or distributions like Ubuntu, Debian, CentOS, etc. Architecture and Components Nagios is not a single component to run. Nagios is actually a suite which provides following components. Nagios IX Nagios IX is the core of … Read more

What Is OpenSSL Library?

OpenSSL is most popular open source cryptography library which provides a lot of tools, libraries, algorithms about cryptography. It is mostly known with Secure Socket Layers (SSL) and Transport Layer Security (TLS) protocols. Supported Encryption Algorithms Encryption is used to make given data unreadable by the intruders. It is mainly used for confidentiality. OpenSSL supports … Read more

What Is Linux PAM (Pluggable Authentication Module)?

Authentication is an important part of the operations systems like Linux. As Linux operating systems are multi-user systems and run a lot of services and complex scenarios they generally need robust and easy to implement complex scenarios authentication systems. Linux Pluggable Authentication a.k.a. Linux PAM is a very robust and dynamic authentication system. In this … Read more

How to Add Ssh Keys with ssh-add In Linux?

SSH protocol provides different ways for authentication. Key based authentication is the most secure one. In order to use key based authentication we should store the key in a command place. SSH agents reads keys and uses for authentication with remote system. We can use ssh-add to store keys in a common path. Key Files Public … Read more