Stay away from suspicious access with fail2ban
A number of suspicious access to Linux servers happens on the Internet every day. Fail2ban is software to protect Linux servers from brute-force attacks. Installation on Ubuntu Linux server: $ sudo apt update $ sudo apt install fail2ban Configuration of…
550 5.7.511 Access denied, banned sender
Before the Christmas holiday, some of our clients using Linode cloud servers reported that emails cannot be delivered to some domains hosted at Microsoft Office 365 from their Postfix SMTP server. We checked that all of them are still in…
Open source event attendance system – badgeprint
To facilitate our conferences and events for open source community, I developed an open source event attendance system in Django and Python. Why do I develop an event attendance system ? We organised technology conferences and events for years, we…
Postfix SMTP – How to setup an email relay system ?
Email relay is an email server which forwards incoming SMTP emails to an another SMTP server. Postfix can be setuped as an email relay. First, you should ensure which domaisn are being forwarded (eg. domain-A-to-be-relayed.com and domain-B-to-be-relayed.net), and hostname of…
How to manage KVM Virtual Machine
virsh is the administration tool of KVM virtual machine, for examples, starting up or shutting down VM operation, control and modify the virtual machine, etc. virsh can be used as an interactive command shell or direct execution with its sub-commands….