SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting and Conformance) are email authentication protocols that are becoming increasingly necessary to run a working email server. Even if you have valid MX, A, and PTR DNS records for your mail server, you may find that your emails are getting rejected […]
Here are instructions on how to set up Molecule 3 to test your Ansible roles using Docker images in Mint 20.2. You can find some additional working code for this in my Github repos like abrt and CloudBees; these use official Red Hat images from the Red Hat Container Registry. Most of these will already […]
Steps to add a mount point to a Red Hat Linux system using LVM: Add a disk in VMware. Ensure the disk is visible on your server. Create a physical volume. Create a volume group. Create a logical volume. Make a filesystem. Mount the volume. (Create the mount point if necessary.) Add it to /etc/fstab […]
One common requirement for a web site, especially in the age of mandatory SSL, is to ensure that its address is a) consistent, and b) forwards to SSL. In other words, when a visitor types in http://www.mysite.com/, http://mysite.com/, OR https://mysite.com/, they should be sent to https://www.mysite.com/. To do this, we’ll set up some Nginx server […]
Running a secure web site provides a better experience for anyone using your site. These days (2018), search engines also favor web sites that use SSL/HTTPS, so utilizing SSL is an important aspect of SEO. But buying a new SSL certificate every couple of years can get expensive, particularly if you run multiple web sites […]
So you want to set up a webmail system. SquirrelMail was a fine community-supported project for many years, but as of July 2017 it seems to have been abandoned by its developers, so we’re going to use Roundcube for our webmail system instead. This guide assumes you have Ubuntu 16 running a MariaDB-Postfix-Dovecot email server […]
Update April 2018: I’d suggest using Let’s Encrypt for this instead. How to create and install an SSL certificate for Nginx 1.10 on Ubuntu 16. (Apache setup here.) This setup also gets you an A on the SSL Labs SSL Server Test. Part I: Create and Obtain your SSL Cert 1. Create your key and […]
This was written to strip local domains from hyperlinks in text files, e.g., www.geoffstratton.com/mylink.html will become /mylink.html. #!/usr/bin/perl -cw # # Strip local domains from link urls. # Each file will be modified in place and a unique backup saved. use strict; my $DEBUG = 0; sub dbg_print { if ($DEBUG > 0) { foreach […]
On my Amazon reading list page I wanted to add a progress bar and ahead/behind schedule counter similar to that on Goodreads. For their reading progress meter, you enter how many books you plan to read, and then your account page shows you a progress bar indicating how many books you’ve read and how far […]
Note: This article describes setting up SpamAssassin 3 to work with a Postfix/Dovecot email server on Ubuntu 16, and it applies to other Debian/Ubuntu variants that use systemd. There are some significant differences in the SpamAssassin config between distros that use systemd and those that use upstart. For the Ubuntu 12/14 version of this article, […]