Linux

A subnet, or subnetwork, is a logical subdivision of an IP network. It’s essentially a smaller network within a larger network, created by dividing the network address space into smaller segments. This division is achieved through a process called subnetting. By dividing the network into smaller segments, subnet allows for more efficient management of network …

“Practical Linux System Administration” by Kenneth emerges as a remarkably comprehensive guide for anyone aspiring to master the intricacies of Linux administration. This book is a treasure trove of practical knowledge, seamlessly blending fundamental concepts with advanced techniques. From the outset, Kenneth’s expertise shines through. He meticulously introduces the Linux operating system, making it approachable …

The noexec option in /etc/fstab (File System Table) in Linux is a mount option that specifies how a filesystem should be mounted, particularly with regard to the execution of binaries. When a partition is mounted with the noexec option, it means that you cannot execute any binaries that are stored on that partition. Understanding /etc/fstab …

To fix the “no matching host key type found” error in SSH, you need to modify your SSH client configuration to accept the host key types offered by the SSH server. This error typically occurs when your SSH client does not support or is not configured to accept the host key types provided by the …

In the world of Linux and Unix-like operating systems, the “Permission Denied” error is a common occurrence that stumps many users, particularly when encountered in situations where file permissions seem to be correctly set. One less obvious but significant cause of this error is the `noexec` mount option. Understanding how this option works is key …

In SSH (Secure Shell), the host key is crucial as it uniquely identifies each SSH server. This key forms the basis for secure, encrypted connections between the server and its clients. When a client connects to an SSH server for the first time, the server’s host key is stored in the client’s known_hosts file. This …

In Linux, getting the SSH host key fingerprint is crucial for verifying the identity of an SSH server before establishing a connection. Here are the methods to retrieve the host fingerprint: Method 1: Using ssh-keygen Local Server: To find the fingerprint of a local SSH server’s host key, use: ssh-keygen -lf /etc/ssh/ssh_host_rsa_key.pub The -l option …

When connecting to an SSH server, especially for the first time, users often encounter a security prompt. This prompt plays a crucial role in the SSH connection process, ensuring the security and authenticity of the server being connected to. The authenticity of host ‘howtouselinux (10.254.175.51)’ can’t be established. ECDSA key fingerprint is SHA256:PgyFiC7Su7BiFBO1Sn8493MMz8/PE+2fJMI/mFfBy9M. Are you …

The error message bash: TMOUT: readonly variable indicates that the TMOUT variable has been set as readonly, which prevents you from changing its value in your current session. This is usually done for security reasons, often in a global configuration file, to enforce automatic logouts for idle sessions. To fix this and change the TMOUT …

Addressing SSH auto-logout issues often involves configuring two key settings: the TMOUT shell variable and the StopIdleSessionSec setting in /etc/systemd/logind.conf.  Each plays a distinct role in session management and inactivity handling. TMOUT Variable: A Bash shell setting that defines the maximum idle time before automatic logout. It is crucial for users experiencing undesired SSH disconnections …