Apt Proxy on Ubuntu is a powerful tool, particularly useful in environments where multiple machines require frequent software updates or installations; it acts as an intermediary server, caching packages to reduce bandwidth usage and speed up subsequent downloads. By configuring an apt proxy, administrators can ensure that, rather than each machine individually downloading packages from ... Read more
Here is the solution if you've got the following error message when updating package lists on Debian (apt-get update): The following signatures were invalid: EXPKEYSIG B188E2B695BD4743 DEB.SURY.ORG Automatic Signing Key The sury.org Debian package repository has changed its package signing key. To fix the error, just download the new key: apt-key adv --fetch-keys https://packages.sury.org/php/apt.gpg Finally, ... Read more
In Postfix configuration, particularly on Debian and Ubuntu systems, you might come across terms like "submission" and "submissions" when looking into the Postfix /etc/postfix/master.cf file. This article explains the differences and use cases for both ports. Postfix Submission Port 587 This is the standard port for email submission as defined by the Internet Message Access ... Read more
pSome internet access providers have port 25 disabled in their routers to prevent spam. If you run your own email server in a data center, you might have to enable the submission port (587) in postfix to be able to send emails from your local email client to your own mail server. Enable Submission Port ... Read more
The world of Linux is diverse, Linux distributions using different package management systems. RPM (Red Hat Package Manager) and Debian's DEB are two of the most common package formats. Occasionally, users of Debian-based systems might need to install software that's only available in the RPM format. This guide covers converting RPM packages to DEB format, ... Read more
The Nginx web server has a max. body size limit of 1 MB for requests as default. This might be too low for file uploads in scripts and you will see the following error message when you try to upload a file: 413 Request Entity Too Large The configuration variable for this option is "client_max_body_size" ... Read more
Winmail.dat files are a unique file format utilized primarily by Microsoft Outlook. These files serve as containers for attachments sent through emails formatted in rich-text. This format can cause compatibility issues, particularly when users of non-Microsoft email clients, such as those on Linux systems, receive attachments. What is a Winmail.dat File? When an Outlook user ... Read more
The bash history is a log file that contains all commands that a user executed on the Linux BASH shell. When you use the "arrow up" key on your keyboard, then Bash will look up the previous command from that file and display it on the screen. You just have to press "Enter" to execute ... Read more
To restart a CentOS system, you can use both the command line (shell) and the desktop environment (GUI). Using the Command Line (Shell) to restart CentOS Open a terminal: You can open a terminal in CentOS by pressing `Ctrl+Alt+T` or by searching for "Terminal" in the application menu. Alternatively, connect to the system using SSH ... Read more
NFS (Network File System) is a distributed file system protocol developed by Sun Microsystems to share files and folders between Linux/Unix systems. NFS allows us to mount the file system over the local network. NFS uses standard client/server architecture for sharing files and directories between Linux-based systems. This tutorial will help you to set up ... Read more