If you need to whitelist an IP address in fail2ban, you can do so by following these simple steps. Edit /etc/fail2ban/jail.conf in your favorite text editor Search for the following section.  It should be near the top of the file: [DEFAULT] # “ignoreip” can be an IP address, a CIDR mask or a DNS host. …

When using SMTP mail from the WordPress mail plugin, and it fails with an error like this:   Connection: Failed to connect to server. Error number 2. “Error notice: stream_socket_client(): unable to connect to someserver.com:587 (Connection refused)   Try to make a telnet connection to the destimation server from the command line on the server …