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…