How to install a CloudFlare origin server SSL certificate into Virtualmin
Background If your Virtualmin website is using Cloudflare as a proxy you can’t use the standard Let’s Encrypt HTTP method to request a fresh certificate.
Security
How to deal with CSP and being contacted by a “security researcher”
Background You might be approached by someone looking for money. They will give you this information (broken English included): Summary: X-Frame-Options ALLOW-FROM https://billing.example.com/login not supported
Unable to restart FirewallD – Found left-over process 1234567 (rmmod)
To restart FirewallD, use this command: service firewalld restart However, if FirewallD refuses to restart, and you check the status using this command: service firewalld
Pentest – Penetration Testing – What is it, and what tools are involved
Penetration testing is popular to check internet exploits. Here are a number of tools and services to help with checking up your security. Here is
How to get L2TP working from the Linux command line
Background This article explains how to get xl2tpd, which has PPPtP capabilibies, working on Linux. This is useful where you have a server environment and
Fail2ban stops working because FirewallD is not running
Observing the fail2ban log file shows that IPs are already banned but still appearing in the list. Closer inspection of the log file shows that
Key based authentication stops if /root permissions are incorrect
On a good server SCP was used to retrieve a remote compressed file. This was saved to the root directory. Thereafter key based authentication stopped
How to test PPTP VPNs from the command line using Ubuntu
Many Windows servers still use Point to Point Tunneling Protocol. It’s tried and tested, but apparently not that secure. MacOS removed it because it’s obsolete.
How to find out why Fail2ban blocked a user
Fail2ban doesn’t have logging to show you that a which “user” gets blocked. The reason is Fail2ban is a low level utility that works across
How to change the password for another user in Linux using passwd
Simply do this logged in as root: passwd other_user