You have configured the following rules. What is the effect? sudo iptables -A INPUT -p tcp --dport 25 -m conntrack --ctstate NEW, ESTABLISHED -j ACCEPT sudo iptables -A OUTPUT -p tcp --sport 25 -m conntrack --ctstate ESTABLISHED -j ACCEPT

Allow Simple Mail Transfer Protocol (SMTP) traffic. Since SSH is on TCP port 22, these rules will have no effect on SSH.

Explanation:

Allow Simple Mail Transfer Protocol (SMTP) traffic.

Inbound and outbound SMTP connections on TCP port 25, which is SMTP's default port, would not be prevented by these rules.

These rules use the Accept action to ensure that Simple Mail Transfer Protocol (SMTP) and Secure Shell (SSH) are not blocked.

Since SSH is on TCP port 22, these rules will therefore have no effect on SSH.

add the following