Hello everyone my name is vijay kumar Devireddy and I am glad to have you back on my episode 69 today we're going to discuss about In security one of the most important things is to ensure that you understand,what openings you have created in your systems.When it comes to computers and networks,most of these openings are going to be created by ports.Now a port is simply a logical communication endpoint that exists on your computer or your server.For example, if you're running a web server,you're going to have port 80 open and listening for inbound requests from your potential visitors.Now ports are classified as either inbound or outbound ports.An inbound port is used when your computer or server is listening for a connection.Just as in my earlier example,the web server had port 80 open, that's an inbound port.It's just waiting for somebody to come along and connect to it.An outbound port on the other hand, is opened by a computer whenever it wants to connect to a server.If my computer is attempting to make a connection to your web server over port 80,well, then my computer is going to open up a random high number port such as port 52363 and it's going to make an outbound request to that web server.Now, what does all this look like in the real world?Well, let's look at an example of how an inbound and outbound port are used when my laptop attempts to connect to a remote server over SSH.First, we have a server at the top of the screen and it has a public IP address assigned to it,and it's listening on port 22,so port 22 is the inbound port awaiting new connections.And in this case, port 22 is open.At the bottom of the screen,I have my laptop that wants to make the connection.Now, my laptop has a private IP address assigned because my network is using NAT at the router and that gives me some additional protections.So, notice at this point my laptop doesn't have any ports opened yet.So now my laptop wants to go and establish the SSH connection.It's going to open up an outbound port on itself,which is going to be some random high number port like 51233 and it's going to send a request to the SSH server over port 22 which is the server's inbound ports and destined for it's IP address in this case, 46.124.63.13.Now once a server receives this request,it has to respond to it.So, it's going to send a packet of information back to my laptop's IP in the outbound port that was open.In this case that's port 51233 and in reality it would be the public facing IP address of my router but for our example, I'm going to use the private IP address of 192.168.1.45.Now, that my laptop has made the request to the server and the server answered that request,we now have a session established and both devices can communicate back and forth as needed.Once that session is over,the connection is going to be closed,my laptop is going to close it's outbound port because it's no longer needed and the server will keep that inbound port open so they can receive requests from the next user who wants to use it.So now that we showed how ports work in the real world,let's talk a little bit more about the ports themselves.In addition to being called inbound and outbound ports,the ports are going to be assigned a number.Now, the number can be anywhere between 0 and 65,535 but this big range is actually divided into three smaller groups.The first group is called the Well-Known ports.This is for any ports that are between 0 and 1023.These are called Well-Known ports because they are designated by IANA the Internet Assigned Numbers Authority and they are going to assign it to commonly used protocols and ports. --- This episode is sponsored by · Anchor: The easiest way to make a podcast. https://anchor.fm/app