Checking for Listening Ports on Ubuntu

First Port Scan on my PC.

droid@droid-OptiPlex-GX520:~$ nmap  127.0.0.1

Starting Nmap 6.40 ( http://nmap.org ) at 2015-05-02 08:43 IST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0021s latency).
Not shown: 994 closed ports
PORT     STATE SERVICE
25/tcp   open  smtp
80/tcp   open  http
139/tcp  open  netbios-ssn
445/tcp  open  microsoft-ds
631/tcp  open  ipp
3306/tcp open  mysql

Nmap done: 1 IP address (1 host up) scanned in 0.29 seconds

Next the command to check who is listening 
on Port 25

droid@droid-OptiPlex-GX520:~$ sudo netstat -tunlp | grep :25
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1281/master    
tcp6       0      0 ::1:25                  :::*                    LISTEN      1281/master

To kill the process 1281
sudo kill -9 1281

A bit about Port 139 :Source
NetBIOS Session (TCP), Windows File and Printer Sharing
This is the single most dangerous port on the Internet. All "File 
and Printer Sharing" on a Windows machine runs over this port. 
About 10% of all users on the Internet leave their hard disks 
exposed on this port. This is the first port hackers want to 
connect to, and the port that firewalls block. 

I have blocked all Ports using GUFW accept 80 which 
I have blocked only incoming ,else will not be able to browse. 

Added this iptables rule:
jedi@jedi-OptiPlex-GX520:~$ sudo  iptables -A INPUT -i eth0 -p tcp --dport 3306 -m state --state RELATED,ESTABLISHED -j DROP