Opening ports in the firewall for the Mail Server

There are standard ports that are used to access most services. For example, accessing a website generally uses port 80 for normal (HTTP) web pages and port 443 for secure (HTTPS) pages. Smtp Smtp generally uses port 25 for connections although there are recommendations for port 587 (see the official documentation for details). Pop and [...]

Common iptables command, cheatsheet

#!/bin/sh #File: /etc/rc.d/rc.firewall # Immediately log and drop any known abusive IPs iptables -A INPUT -p tcp -s 87.118.104.44 -m limit –limit 1/minute  –limit-burst 10  -j LOG –log-prefix “[DROPPED_NODE]“   –log-level 4 iptables -A INPUT -p tcp -s 87.118.104.44 -j DROP # Allow from any to any on 127.0.0.1/32 iptables -A INPUT -s 127.0.0.1/32 -j ACCEPT [...]