Linux and DevOps

🔅 Linux System Engineer: iSCSI Storage Area Networks 🌐 Author: Grant McWilliams 🔰 Level: Advanced ⏰ Duration: 1h 23m

🌀 Become a Red Hat Certified Engineer (RHCE). Study objectives from the RHCE certification exam related to iSCSI storage networking.

📗 Topics: Linux 📤 Join Linux Mastery for more courses

🔅 Linux System Engineer: Kernel Tuning and Remote Logging 🌐 Author: Grant McWilliams 🔰 Level: Intermediate ⏰ Duration: 1h 37m

🌀 Study to pass the RHCE exam—the benchmark certification for Red Hat Enterprise Linux. This course covers Linux kernel tuning for performance optimization, and remote logging.

📗 Topics: Linux Kernel 📤 Join Linux Mastery for more courses

#meme

🐧 Linux directory structure overview

🐧 Know platform architecture Websites always host the static builds of the latest stable version for different platforms like amd64, i686 or arm64. If you don't know what platform architecture you have in your machine, use this command:

uname -m

Based on the returned value, you know:

i686: It's a 32-bit architecture based on Intel or AMD x86_64 or amd64: It's a 64-bit architecture based on Intel or AMD arm64 or aarch64: It's an 64-bit architecture based on ARM

4. Avoiding Duplicate IPs

When assigning static IPs, devices use GARP to check if an IP address is already in use on the network. This is a simple and effective way to prevent IP conflicts. For example, before assigning itself an IP, a device sends a GARP request. If no response is received, it proceeds with the configuration.

3. Redundant IP Addresses

In high-availability setups like Hot Standby Router Protocol (HSRP) or Virtual Router Redundancy Protocol (VRRP), GARP is used to broadcast the ownership of a virtual IP address. This ensures that devices communicate with the active router, even during failover events. Example, If a backup router takes over the virtual IP after the primary router fails, it sends a GARP message to update all devices' ARP tables with the new MAC address.

2. Announcing a Node’s Existence

GARP is often used to announce the presence of a new node or device on the network. This ensures other hosts can immediately recognize and communicate with the new device. Here is an example: When a new virtual machine or router interface comes online, it sends GARP to let the network know it’s available.

📶 Use Cases of GARP 1. Updating ARP Mapping

GARP helps devices update their ARP caches when a MAC address changes or when a new device joins the network. This avoids communication disruptions due to outdated IP-to-MAC mappings. For example, A server changing its network interface card (NIC) can use GARP to inform other devices of its new MAC address.

📶 Here are some important key points to take note of: 1. GARP works through broadcasts and is not unicast like traditional ARP responses. 2. It does not receive a reply but informs the entire network. 3. Critical in dynamic environments, like virtualization or high-availability systems.

📶 Networking Crash Course GARP

Gratuitous Address Resolution Protocol (GARP) is a specialized feature of ARP where a device sends ARP messages without being explicitly requested. Unlike standard ARP, which is reactive (responding to ARP requests), GARP is proactive. It is used to announce a device's presence, update ARP tables, or claim ownership of an IP address on a network. When a device sends a GARP message, it broadcasts its IP and MAC address to all hosts on the network. This helps devices update their ARP caches without waiting for communication requests.

Here is how GARP works: 1. Broadcast: A device sends an ARP packet with its own IP address as both the source and destination, ensuring all devices on the network see it. 2. Switch Forwarding: The switch forwards the GARP message to all interfaces, excluding the one it was received on. 3. Table Update: Other devices update their ARP tables with the IP/MAC...

🐧 Linux boot process overview

🐧 Linux File Permissions

📱 50 GIT & GITHUB Interview Q & A