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Are you a content creator or a blog author who generates unique, high-quality content for a living? Have you noticed that generative AI platforms like OpenAI or CCBot use your content to train their algorithms without your consent? Don't worry! You can block these AI crawlers from accessing your website or blog by using the robots.txt file.
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The post How to block AI Crawler Bots using robots.txt file appeared first on nixCraft.
In this quick tutorial, you will configure a user to use key-based authentication for SSH under a macOS desktop.
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The post macOS configuring SSH Key-based Authentication appeared first on nixCraft.
All Linux and Unix servers are managed manually or by automation tools such as Ansible using ssh. For example, say you have a server at Linode or AWS. Then you copy your public ssh key to a remote cloud server. Once copied, you can now login to those servers without a password as long as ssh keys are matched. It is the best practice. Unfortunately, you are not protecting ssh keys stored on a local desktop or dev machine at $HOME/.ssh/ directory. If your keys are stolen, an attacker can get access to all of your cloud servers, including backup servers. To avoid this mess, we can protect our ssh keys stored on local dev/desktop machines using physical security keys such as YubiKey.
In both cases, you need to insert your YubiKey (or any FIDO2 compatible hardware key) into a USB port and complete the authentication. In other words, ssh login will not work when malware or attacker has stolen your passphrase and ssh keys as they can not insert YubiKey and press the button on it to complete OTP for ssh keys.
In the corporate environment, we have a bastion host that allows ssh access with Yubikey. It is a special-purpose server on a network specifically designed and configured to withstand attacks. The server generally hosts an sshd process, and all other services are removed. Once logged into bastion host, you can access all other cloud servers easily.
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The post How To Set Up SSH Keys With YubiKey as two-factor authentication (U2F/FIDO2) appeared first on nixCraft.
Did you know? You can turn off the banner in Linux or Unix using a particular file. When you log in using ssh or other methods, you will find tons of information on the screen. Here is how my FreeBSD home server login looks:
Default motd with my hardware and other info
The first one is /etc/motd, and the second is the output of neofetch called from ~/.profile file. And my Ubuntu Linux box showing stuff too when I login using the ssh command:
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The post Quick Tip: Turn off the login banner in Linux or Unix .hushlogin file appeared first on nixCraft.
Typically we use the lscpu command or /proc/cpuinfo command on Linux to check CPU information. I recently found another simplistic yet fancier CPU architecture fetching tool inspired by neofetch, pfetch or screenfetch. Let us see how to install cpufetch on Linux, macOS, Android, and Windows to fetch CPU details.
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The post cpufetch – awesome CPU architecture info tool for Linux and macOS appeared first on nixCraft.
Despite some severe bugs in sudo, it remains the defacto tool to gain root shell or run command as another user on Linux, macOS, and Unix-like systems. The sudo command allows the system administrator to grant an individual user access to unprivileged commands. For instance, I can give developers the ability to restart the Apache webserver or PHP/Python process on a Linux server. Let us see how to remind developers and unprivileged users about the power of sudo for fun and profit. In this quick tip, I will show you how to add some spice to your sudo session with a lecture file on Linux or Unix.
The post Adding spice to your sudo session with a lecture file on Linux or Unix appeared first on nixCraft.
How do I remove all the carriage returns \r (^M) from a file in Unix using the command-line options?
The post How to remove carriage return in Linux or Unix appeared first on nixCraft.
Any logged-in unprivileged user can abuse an old bug in sudo to gain root privileges. It was rated as an important security issue for Linux and Unix-like operating systems. The Qualys research team has discovered the heap overflow vulnerability in sudo itself has been hiding in plain sight for nearly 10 years. The bug allows any local users to gain root access without authentication (no user's password needed). We need to apply patches to our operating systems as soon as possible.
The post Critical bug in sudo puts Linux and Unix systems at risk appeared first on nixCraft.
Homebrew is an essential package manager for developers, sysadmins, and power users on macOS. Homebrew allows us to install the latest and updated version of popular applications, packages, and developer tools. Homebrew is the painless way to install required packages on your Mac. For instance, we can install PostgreSQL, Python, PHP, Bash, Nginx, Apache, and much more using brew command. This page explains how to install and use Homebrew on the macOS system to get missing packages. Homebrew installs the apps you need that Apple didn't include in their base operating system or app store.
The post How to install Homebrew on macOS to use the brew package manager appeared first on nixCraft.
We use the df command to show how much disk space is free on mounted file systems in Linux, macOS, and Unix-like systems. We also have the du command to estimate file space usage. We now have another fancy and fantastic looking tool called duf to display statistics on free disk space in Unix, Linux, macOS, *BSD, Android, and Windows written in Golang.
The post duf – Disk Usage/Free Utility for Linux, BSD, macOS & Windows appeared first on nixCraft.
The last ten years in the computer and IT security world are crippled with so many vulnerabilities. We saw massive cloud computing adoption and end-users using mobile devices with high speed 4G LTE networks. A threat actor may have exploited such weakness in modern computers and networks. Let us look into top vulnerabilities and the attack surface in this decade (2010-2020) that affected Linux/Unix, macOS, IT, cloud-computing, and computers in general.
The post Significant vulnerabilities that crippled IT world this decade (2010-2020) appeared first on nixCraft.
The bashtop is an impressive Linux resource monitor that shows usage and stats for processor, memory, disks, and network. However, it suffers from bash itself, and cross-platform support is a nightmare. Now we have the Python port of bashtop. We can use a resource monitor that shows usage and stats for CPU, RAM, SSD (hard disk), network, and processes information in a lovely format.
The post bpytop – Awesome Linux, macOS and FreeBSD resource monitor appeared first on nixCraft.
Current GNU/Bash maintainer Chet Ramey announced the latest major release, Bash 5.1, on December 7th, 2020. Bash is the default shell on many Linux distros and popular among developers, especially those working with Linux containers. It is the fifth major release of bash. It came with a new enhanced random number generation and added a new variable called SRANDOM. Let us see how to install and use newly released GNU/BASH 5.1 on Linux.
The post GNU/Bash 5.1 released with the random ${SRANDOM} number engine appeared first on nixCraft.
I brought eggs from the market, and it says best before 20 days from the date of packing. Say my egg box was packed on 29/July/2020. How do I add days to date using Linux CLI? I want to find out date 29/July/2020 + 20days using the CLI, and how do I do it?
The post How to add days to date and get new date on Linux appeared first on nixCraft.
There is a new kid in town for resource monitoring on Linux called bashtop. As the name suggests, the entire tool coded in the bash script itself that displays usage and stats for CPU, RAD, HDD/SSD, network, and other resources. Let us see how to install and use bashtop, which is an awesome Linux resource monitor. You don't need a Linux desktop to install it. You can also install this app on macOS/FreeBSD provided that you meet software requirements.
The post bashtop – Awesome Linux resource monitor that shows usage and stats for processor, memory, disks, and network appeared first on nixCraft.
One of the essential tasks for developers and sysadmin is to get an alert notification about failed services or running out of disk space and other critical failures. Let us see how to send or push a direct message to a mobile device powered by Apple iOS or Google Android phone.
The post How to push/send message to iOS and Android from Linux CLI appeared first on nixCraft.
The cat (short for concatenate) command is one of the most frequently used flexible commands on Linux and Unix-like operating systems. Say hello to bat Linux command, which is a cat command written in Rust programming language. The bat command comes with syntax highlighting, git integration, and works as is a drop-in cat command replacement. Let us see how to install bat on Linux and Unix system for fun and profit.
The post bat Linux command – A cat clone with written in Rust appeared first on nixCraft.
Vim is my favorite text editor and version 8.2 released. The new version includes support for popup windows and text properties. Popup windows can be used for many purposes. For example, a list of choices can be displayed, where the user selects an entry with keys or with the mouse. There is also a new vim game released named as killersheep to show you new capabilities of Vim. Let us see how to install and play killersheep.
The post killersheep – Silly game for Vim version 8.2 appeared first on nixCraft.
I noticed that my default shell set to zsh on Macos Catalina. How do I change my default shell to bash on Macos Catalina using the command line or GUI options?
The post Change default shell to bash on Macos Catalina appeared first on nixCraft.
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