How to use sudo and su to elevate yourself to root and then to another user
At times on a Linux server you want to switch to another user. One example could be one a shared server whereby you need to
Security
How to generate RSA public and private key pair in PKCS #8 format
This article explains how to create RSA public and private key pairs in PKCS#8 format. This might be required if an upstream supplier asks
Fail2Ban ssh-ddos Issue with New Install of Virtualmin and Ubuntu 18.04
Background On a newly installed Virtualmin server you might see events complaining about a missing config file for filter.d/sshd-ddos as per below: Jul 13 19:57:35
How to covert a .ppk SSH key file to .pem SSH key file
Background A client might provide you with a .ppk file, which is typically used with Putty and SSH connections. If, however, you are using Ubuntu
The client lacks sufficient authorization whilst renewing a Let’s Encrypt certificate on a Virtualmin server
Background This is a complex issue and the interplay between various technologies such as DNS, HTTP Challenge, website (Apache / NGINX), permissions, and redirections can
DNS name does not have enough labels error when requesting a Let’s Encrypt server certificate
Whilst trying to retrieve a new Let’s Encrypt certificate on a Virtualmin server, the following error was encountered: Requesting a certificate for server_name from Let’s
How to block and and unblock IP addresses using FirewallD
What is FirewallD? FirewallD (Firewall Daemon) is a nice alternative to iptables but still uses iptables behind the scenes. Yet it’s much simpler and easier