How to open a port on Debian?

Question

linux

Opened easily on ubuntu
iptables -A INPUT -p tcp --dport 3306 -j ACCEPT
On debian 7 I prescribe and the port is closed
netstat shows LISTEN status
but nmap from another node shows closed status.
And also explain why netstat shows that the port is open and what utilities are better to see open ports?

Answer 1

Show the output of the commands:

netstat -ntpua | grep 3306
iptables-save

Answer 2

iptables -I INPUT 1 -p tcp --dport 3306 -j ACCEPT

Answer 3

In general, there is no special sacristy between Ubuntu and Debian. Ubutu is based on Debian. How many network interfaces do you have?