In this lecture, we will learn about all the three states of a port and the first scan.
Right?
So let me scan my target network first.
So type and map.
Now hyphen uppercase f now write the URL or IP address hyphen uppercase f flag means faster the default
and map scan scans the most popular thousand ports, whereas the fast scan only scans the most popular
100 ports.
So this scan is ten times faster than the default and MAP scan.
So let me hit enter.
As you can see, scan is complete.
Fast scan scanned a hundred ports.
As you can see, 91 ports are open.
So re closed and remaining nine ports are either open or filtered.
As you can see here, we have a few open ports such as FTP and search.
Right.
So what does an open port mean?
And open port means it is open and available to everyone.
It is accepting new connections.
Open ports can be problematic if they are not protected properly.
There are some ports that hackers target the most.
Port number 21 and 22 are among them.
Port number 21 runs FTP and 22 runs SSH service.
Right.
As you can see now, these two ports allow us to access the servers remotely.
You just need to enter the correct username and password.
Then we can use our access the server remotely.
Now what does an open port mean from a hacker's perspective?
If a port is open, then anyone can access it, right?
Whether it is the system, admin or attackers.
Let's say if port number 21 or 22 is open, then attackers can brute force FTP and SSH services.
If login credentials are weak, then username and password can be cracked very easily.
Remember, hackers can only launch attacks if port is open, right?
If it is filtered or closed, then it makes attacks irrelevant to a great extent.
This is why a map is so important for attackers, right?
It provides the openings, right?
Once attackers know that the port is open and available, then attacks can be launched.
Now a second state is filtered.
Filtered means port is protected by a firewall only the authorized devices can access the port and third
state is closed.
If a port is closed, then it means it is closed.
No one can access or use it.