DNS is a system by which a browser or other software converts a domain name to a IP4 or IP6 address. Each time we access a website the browser needs to convert the domain name to a IP4/IP6 address using a DNS server. The DNS server configured on our computer could be automatically selected by…
The OS version of a Linux distribution can be determined by using the command-line interface as well as a graphical user interface. In Linux, CLI is preferred over GUI as it provides more control over the OS. In this article, we will mostly focus on the command line methods which can be used to check…
When the “Too Many Open Files” error message is written to the logs, it indicates that all available file handles for the process have been used (this includes sockets as well). In a majority of cases, this is the result of file handles being leaked by some part of the application. ulimit is a command…
Most UNIX-like operating systems, including Linux and macOS, provide ways to limit and control the usage of system resources such as threads, files, and network connections on a per-process and per-user basis. These “ulimits” prevent single users from using too many system resources. Sometimes, these limits have low default values that can cause a number…
Linux file system is generally a built-in layer of a Linux operating system used to handle the data management of the storage. It controls how data is stored and retrieved. It manages the file name, file size, creation date, and much more information about a file. We will cover how to check file system type…
fsck is a front-end program and it calls the respective program for the specific filesystem to run. Fsck usually runs after the system fails to boot, the file system becomes corrupted, or the attached drive fails to function properly. When we need run fsck command in Linux how to use fsck command in Linux Here’s…
On a Linux system, TCP ports in a reserved range (typically less than 1024) can only be bound by processes with root privilege. If we’re trying to bind a port in a Linux environment less 1024, we will receive a “Permission denied” error. Listen tcp :80: bind: permission denied So we should do either: Reason…
Security-Enhanced Linux (SELinux) is a security architecture for Linux® systems that allows administrators to have more control over who can access the system. It was originally developed by the United States National Security Agency (NSA) as a series of patches to the Linux kernel using Linux Security Modules (LSM). Security Enhanced Linux (SELinux) provides an…
Secure Sockets Layer (more commonly referred to as SSL) is the known industry standard used by millions of websites for protecting online transactions with their customers. SSL used for making an encrypted link between a web server and a browser. This encrypted link guarantees that all data transferred between both ends remain private and intact….
Postfix is a popular open-source mail transfer agent (MTA) that routes and delivers email. Occasionally, as part of the administration of this service, users will view, flush, and purge Postfix mail queues. These actions facilitate the manipulation of email delivery, enabling message reprioritization and/or cancellation. Such actions are often taken when messages are deferred or…