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Showing posts from May, 2021

How to use the ssh-keygen Command in Linux

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Secure Shell (also known as SSH) is a cryptographic network protocol. Ssh-keygen is a tool in the Linux distro that is used for creating new authentication key pairs for SSH. Such key pairs are used for automating logins, single sign-on, and for authenticating hosts. In simple word, ssh keygen allow a user to connect to a remote system without supplying a password It is also used to transfer files from one computer to another computer over the network using a secure copy ( SCP ) Protocol. In this tutorial post, we will show you how to set up and use password-less login on Linux/Ubuntu, RHEL/CentOS, and Fedora using ssh keys to connect to remote Linux servers without entering a password. By using Password-less login with SSH keys will increase the trust-relation between two Linux servers for easy file synchronization or transfer. In this example, we will set up SSH password-less automatic login from server 192.168.1.101 as user sr to 192.168.1.102 with user server . Note :- Username i

Getting help on Linux commands

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Getting help on Linux commands There are 5 methods to get help on Linux commands, they are, Display single line description about command *      Use -h or-help option on command *      Read "info" document on command *      Read "man" page of the command *      Using "apropos" to search man pages Each of these methods are discussed in detail. Method 1 of Linux Help The first method of getting help on Linux commands is to display a single line description about the command. You can use " whatis " followed by command to access the basic information. Take a look at the image, it shows the one line description about the command. " rename " The brief description of "whatis command is, " whatis " searches a set of database files containing short description of system commands for keywords and displays the result on the standard output. Only complete word matches are displayed. Example:-  " $ whatis cron "   Method 2 o

Linux repository and packages

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Linux repository and package Linux repository: A software repository contains software packages When you search via the inbuilt Linux Software Center or use a Linux tools, you are shown a list of all the packages within the repositories available to your system. A software repository can store its files on one server or across many different servers known as mirrors   Linux package In Linux distributions, a " package " refers to a compressed file archive containing executable and data files that come with a particular application The files are usually stored in the package according to their relative installation paths on your desktop system. The contents of control file inside a Package are: Package Name and version Number Architecture support like 1386 (32-bit) or i686 (64bit) Installed Size and location Dependencies, Homepage and Description. There are 2 types of Packages, they are: 1.      Source code package is a suite of files related to one program, it contains source

Basic Networking Commands in Linux

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Basic Networking Commands in Linux A network is a group of computers and computing devices like mobile phones, printers and scanners, etc.. these devices are connected through cables or wireless media. Computers are connected in a network to exchange information or resources with each other. Computer loaded with Linux Operating System can also be a part of a network whether it is a small or large network by its multitasking and multi-user natures. Maintaining of system and network up and running is a task of a System/ Network Administrator's job. Ifconfig command Ifconfig (also known as Interface Configurator) , is the first type of basic command used by network administrators. This command is used to view the IP address and MAC address of the system. Using ifconfig, you can enable or disable an interface on demand as required. Also, ifconfig with an interface (eth0) command only shows specific interface details like IP Address, MAC Address, etc. The command shows the desired outpu

How to Hide Apache, Nginx, or PHP version on Ubuntu

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How to Hide Apache, Nginx, or PHP version on Ubuntu For an attacker, it is very easy to discover valuable information such as the web server version, server operating system, and PHP version. it is recommended that you disable or hide this information from attackers who might be targeting your server by requiring you to know whether you are running PHP or not, Apache or Nginx. In this tutorial post, we are going to show you how to hide this sensitive information (Hide Apache, Nginx, or PHP version) on the Ubuntu Server Operating system. Step1. Let's check Header Details of any Website. You can use wget or curl command to fetch header details of any website via command line. curl -IL https://some-server-ip-OR-domain-name/ curl -IL https://vetechno.in/ OR wget --server-response --spider http://example.com/ When you run the above command you will get the below output. As you can see it clearly visible web server version, php version and other sensitive information. root@vetechno:~#