> Add the following firewall rules to /etc/sysconfig/iptables. This is > to open ports for services/daemons listening on TCP ports 25, 465, and > 587.
/etc/sysconfig/iptables sounds like RHEL/CentOS, on Debian it might be /etc/iptables/rules.v4 or rules.v6 > -A INPUT ! -i lo -p tcp -m state --state NEW -m tcp --dport 25 -j ACCEPT /etc/sysconfig/iptables is for ipv4 only, if your server is reachable via ipv6 don't forget to add rules to /etc/sysconfig/ip6tables In case you have ipv6 and use ipv4 only you can configure "inet_protocols" in main.cf. > Reload firewall rules. > > # service iptables restart This works for compatibility reasons, RHEL 7/8 redirects this to systemctl restart iptables Best regards Gerald
