The Linux Foundation’s Post

This Secure Software Development course covers: - Security basics, such as the risk management process - OWASP Top 10 vulnerabilities - CWE Top 25 - Secure design principles - How to reuse external software with security in mind

The (software) world nearly collapsed recently. A state actor (presumed) _almost_ got a backdoor into every Debian and RedHat system. Commits were pushed and released into nightlies via the xz Utils library. I say software world because much of the world's software runs on Debian or RH-based operating systems. A demo of the exploit: https://lnkd.in/ehsrSkMN An excellent article covering it: https://lnkd.in/eMWRaV_X

#Day15 💻Unlocking Linux Essentials! Today, I covered the following: 1.Updating Software: Keep your system up-to-date! Run `sudo apt update` to refresh the package list, then install required software with `sudo apt install package_name`. 2. SSH (Secure Shell): Securely connect using public/private key encryption. The server encrypts a message with your public key, and your machine decrypts it with the private key, ensuring secure identity confirmation without transmitting sensitive data. 3. File Search: Use `find / -name filename` to locate specific files and get their exact paths. 4. Monitoring System Processes: The `top` command provides a comprehensive view of system processes, CPU performance, and memory usage, aiding in monitoring currently running processes for system management. 5. Disk Space Analysis: Stay aware of disk space utilization! `df` reports used and available disk space on filesystems. Add `-h` for a human-readable format to easily understand space allocation. 6. Process Information: Utilize `ps` to gather information on running processes, including their Process Identification Numbers (PIDs), crucial for system management. 7. Troubleshooting with 'tail': Need to troubleshoot? Use `tail` to display the most recent lines of a file, often containing pertinent information for debugging or issue resolution. With this, I completed all the 6 Modules of the course on Linux by Chegg Skills https://lnkd.in/g_7cvq8y. Simplified content indeed💡 Opencode NIT Rourkela #25daysforcysec #cybersecuritychallenge #LinuxCommands #SystemManagement #SSHEncryption #TechTips

Tired of typing passwords every time you log in to your server? 🤯 Check out this hands-on project that teaches you how to set up SSH certificates for seamless, secure access! 🔒 No more password hassle, just smooth sailing into your local experimental environment. 😎 Learn the step-by-step process and level up your server security game! 💪 Enroll now and say goodbye to password woes forever. #LabEx #Programming #Course #Linux

𝐇𝐨𝐰 𝐜𝐚𝐧 𝐜𝐫𝐚𝐬𝐡𝐞𝐬 𝐥𝐢𝐤𝐞 𝐂𝐫𝐨𝐰𝐝𝐒𝐭𝐫𝐢𝐤𝐞 𝐛𝐞 𝐚𝐯𝐨𝐢𝐝𝐞𝐝 𝐢𝐧 𝐭𝐡𝐞 𝐟𝐮𝐭𝐮𝐫𝐞? Transitioning to alternative operating systems might be the solution you need 🤷♂️  Linux, with its various distributions tailored to different purposes, can offer stability and security in the face of such risks. Here are some noteworthy options: 𝐂𝐞𝐧𝐭𝐎𝐒: Because its software is simple and light, CentOS runs faster than other Linux distributions. The operating system has a *longer upgrade cycle, lasting approximately five years*. (Other distributions have shorter cycles.) Because of the more frequent updates, those other distributions may be less reliable at times. As a result, CentOS is regarded as a stable operating system. 𝐅𝐞𝐝𝐨𝐫𝐚: Fedora is also known for being a stable and dependable operating system. 𝐃𝐞𝐛𝐢𝐚𝐧: Debian is a stable Linux distribution, but it also lets early adopters try out packages that aren't quite ready yet. 𝐑𝐞𝐝 𝐇𝐚𝐭 𝐄𝐧𝐭𝐞𝐫𝐩𝐫𝐢𝐬𝐞 𝐋𝐢𝐧𝐮𝐱: Red Hat Enterprise Linux (RHEL), which calls itself the "world's leading enterprise Linux platform," is used for a lot of different things, such as making software and running hardware. RHEL is well-known for its stability and speed. 𝐋𝐢𝐧𝐮𝐱 𝐌𝐢𝐧𝐭: Mint has become one of the most popular Linux distributions since it first came out in beta in 2006. You can search for and install software visually using an internal software manager that works like the App Store. 𝐎𝐩𝐞𝐧𝐒𝐔𝐒𝐄: OpenSUSE gives its users a stable environment and works well with almost all of the best Linux desktop apps. 𝐌𝐚𝐧𝐣𝐚𝐫𝐨: Manjaro, which was released in 2011, has quickly become one of the most popular Linux distributions. 𝐄𝐥𝐞𝐦𝐞𝐧𝐭𝐚𝐫𝐲: Elementary OS, which was released in 2011, distinguishes itself from other distributions by including its own desktop environment called Pantheon. 𝐎𝐒 𝐙𝐨𝐫𝐢𝐧: For those new to Linux distributions, Zorin OS is a good place to start. Its user interface looks like Windows. 𝐊𝐚𝐥𝐢 𝐋𝐢𝐧𝐮𝐱: Kali Linux is the best distribution for ethical hacking objectives. #CyberSecurity #Linux #CrowdStrike #BusinessLosses

In the following post I'll share how I run into udev and how I could bypass the restrictions that it presents in order to use it as a persistence mechanism in a red team operation. “udev is widely known among system administrators. It’s a device manager for the Linux kernel that allows users to manage devices in the /dev/ directory and create actions based on hardware events. Among the capabilities of udev is the execution of scripts based on hardware events (such as detection), which makes it a good candidate to be employed as a persistence mechanism. To my surprise, at the time I ran into udev there was no subtechnique listed in MITRE ATT&CK matrix; and the references on the Internet didn't address the constraints imposed by udev and its evasion. This fact led me to start a mini-research and explore this possibility.” #redteam #persistence #linux Keep reading at:

From Confusion to Clarity: Demystifying Linux File Permissions As a newbie in the Linux world, I often found myself blindly executing commands without fully comprehending their underlying mechanisms. One such command was chmod, the tool for managing file permissions. While I knew it controlled access to files, I struggled to remember the exact syntax and often ended up frustrating myself with failed attempts. Determined to conquer this knowledge gap, I delved into the intricacies of Linux file permissions. And let me tell you, the journey was enlightening! I discovered that file permissions are governed by three categories: owner, group, and others. Each category is assigned three basic permissions: read (r), write (w), and execute (x). To illustrate, let's consider a file named myfile.txt. If the owner has read and write permissions, they can view and modify the file's contents. If the group has read permission, group members can access the file's contents but cannot modify them. And if 'others' have execute permission, anyone can run the file as a program. The chmod command allows us to manipulate these permissions. For instance, to grant read and write permissions to all users, we would use the following command: chmod ugo+rw myfile.txt This command translates to: ugo: Apply the changes to the owner (u), group (g), and others (o). +rw: Add read (r) and write (w) permissions. Understanding Linux file permissions is crucial for maintaining data security and ensuring smooth system operation. It empowers us to control access to sensitive information and protect our files from unauthorized modifications. So, fellow Linux enthusiasts, don't let file permissions baffle you. Embrace the learning process, and you'll be well-equipped to navigate the Linux world with confidence and clarity. #linux #linuxcommands #foundation #engineering #filepermissions

🚀 Unlocking the Secrets of Live RAM Monitoring in Linux! 🚀 Hey LinkedIn Family, I'm excited to share my latest article on a topic that every Linux enthusiast and system administrator will find invaluable - "How to Read Live RAM in Linux". 💻🧠 In this comprehensive guide, I delve into the essentials of monitoring your system's RAM usage in real-time. Whether you're optimizing performance for a high-traffic server or just curious about your system's memory consumption, this article provides practical, hands-on techniques to keep you informed and in control. 🔍 What you'll learn: Using command-line tools like free, vmstat, and top Interpreting /proc/meminfo for in-depth insights Leveraging htop for a visual representation Writing custom scripts for continuous monitoring I believe this knowledge is crucial for maintaining the efficiency and reliability of Linux systems. Understanding live RAM usage can help in diagnosing issues, optimizing resource allocation, and ultimately ensuring smooth and efficient operations. 📖 Read the full article here: https://lnkd.in/e2ZNVUBw Your feedback and thoughts are always appreciated. Let's dive into the world of Linux together and enhance our skills! 🚀 Credits Deepak Maurya #Linux #RAMMonitoring #SystemAdministration #Tech #OpenSource #LinuxTips #PerformanceOptimization

Software Engineering Insight Part 1 Did you often get disconnected after a few minutes not interacting with SSH client? Let's say you are connected to a SSH client, then you leave for lunch, after you came back, the SSH client have been disconnected, you connect it again, but it can get pretty annoying if you need to do it multiple time a day. Turn out there is a way you can make the SSH client stay connected as long as it is receiving responses to its keep-alive messages from the server. Add these options to your SSH config file, usually located in ~/.ssh/config: ``` Host * ServerAliveInterval 60  ServerAliveCountMax 120 Host 11.111.111.11 User example IdentityFile ~/.ssh/id_rsa_example ``` Explanation: - `Host *` means apply these settings (`ServerAliveInterval` and `ServerAliveCountMax`) to all hosts defined in this config, basically global setting. - `ServerAliveInterval` define a timeout interval in seconds, after which if no data has been received from the server, the SSH client will send a message to the server requesting a response. In this case, it's set to 60 seconds, which means that if the client doesn't receive any data from the server for 60 seconds, it will send a keep-alive message to the server. - `ServerAliveCountMax` define the number of server alive messages which may be sent without receiving any messages back from the server. If this limit is reached while server alive messages are being sent, the SSH client will disconnect from the server. In this case, it's set to 120, which means that the client will disconnect if it doesn't receive any response from the server for 120 consecutive keep-alive intervals. - `ServerAliveInterval 60` and `ServerAliveInterval 120` means the SSH client will disconnect if it doesn't receive any response from the server for 120 * 60 = 7200 seconds, which is equivalent to 2 hours. Thanks for reading! I hope this insight is helpful for you. #Itsavirus #Linux #SSH

🛑 Instead posting yet another link to the OpenSSH vulnerability, let's dive into the underlying bug: ➡️ OpenSSH calls the syslog() function within a signal handler. ➡️ On UNIX systems, signals can interrupt code execution at any time. ➡️ If both the current code and the signal handler modify/use the same data structures, it results in undefined behavior, like dead locks, corrupted data or code execution. 🔧 To avoid such bugs, consider one of these options: ✅ Use only functions in signal handlers that are explicitly marked as safe! See https://lnkd.in/dme2aGsE ✅ Block signals in critical regions ✅ Handle signals synchronously using signalfd() or similar APIs.