So I have a question. Can server A somehow restrict me and only allow connections to the port on the remote server B and not allow me to connect me to any other port on remote server B? Have you seen such a restriction before and if yes then what would be the reason behind such a restriction?
Thank you. Not quite sure exactly what restriction you mean but you can restrict on destination port and ip and source port and IP if that helps rgds steve.
Hi Steve, So here is the scenario. The webserver A has the port open for any incoming requests. The webserver A hosts a website and one of the pages of that website has C code which makes API calls to a remote server B. So my questions are:- 1. Is it possible for the network admin to disallow API calls to ports other than ? What could be the reason for such a restriction? After all, how can restricting a destination port give you any sort of advantage? Port is just a number on which the server listens.
Please help. Yes you can filter incoming traffic on port, ip address and protocol even on basic firewalls. Restricting ports is for security reasons Rgds Steve. I want to read a data from a machine which supports open protocol if the machine is in network and if I know IP address and port number socket how can I read a data from it I know it send and receive data in packet format. Thank you, Steve! Hi Not quite sure of what you mean exactly but load balancing is quite common.
Question: When a program on your computer sends or receives data over the Internet it sends that data to an ip address and a specific port on the remote computer. How does my computer know what port a specific application is working on another computer to populate the TCP Header?
When Machine A connects to machine B. The source ip and port are contained in the connection packet as well as the destination port and IP address. Hi You need to use DNS. Most devices have MDNS enabled.
Great site. I have a quick question. And it must also include its own IP address and port number. But it is not required to include its own IP address and port number.
TCP is a connection orientated protocol and so the destination device needs to know who to send a reply to. Can Server and client share the port number, eg : Server is listening at port num : and client also listens on the same port num : Yes providing they are on different hardware. Machines use 16bits for the port numbers hence the limitation of 64, Good job Steve.
I have a question, and it goes like this: if i have 2 browsers from my PC connecting to the same service, for example both browsers are connecting to google. Meaning can more than one socket connect to a socket at the same time? Yes they use the same IP and port on the Google server but different ports on the client.
Hi, Thanks for this information sharing. It is very well explained. I have following doubt, What I understand is TCP protocol takes care of data transmission error that duplication of packets or packet in true form delivered to other end.
This is not done in UDP protocol. Could you please clear my doubt. Answer will help me alot. Google and Yaoo have different IP addresses. Does that make sense?
The IP address of google and yahoo is different. The port number 80 is the open port of server. If I want to connect Google server,I will open a new port,for example I will open port , at the same time I will open another port to connect with Yahoo server. I have few doubts though, hope you can clear them: 1.
Can you tell if a server uses a single port 80 on all of its connections to clients? Or is it used only by the Welcoming socket? Can port 80 handle multiple connections simultaneously? A port e. No… a session needs to be established at said layer. A is lessening on port SSL for incoming packets and firewall infront is in addition to alllowing to A also policing 25, 80 etc Whatever…. The infographic is so good that anybody can understand at a glance.
I request the author to post more articles on networking. Your email address will not be published. The IP address identifies the device e. Analogy If you use a house or apartment block analogy the IP address corresponds to the street address. All of the apartments share the same street address. However each apartment also has an apartment number which corresponds to the Port number. Port Number Ranges and Well Known Ports A port number uses 16 bits and so can therefore have a value from 0 to decimal Port numbers are divided into ranges as follows: Port numbers — Well known ports.
TCP Sockets A connection between two computers uses a socket. A socket is the combination of IP address plus port Each end of the connection will have a socket.
Please rate? And use Comments to let me know more. Thanks Steve for making it vividly simple. Hi I have a software which creates 4 sockets with apparently random numbers the person who developed left no documentation However, the client which connects to it only sends over port Is there a way to interconnect those random number sockets and port so the client is able to connect to the software?
Thanks in advance and God bless. Hi not sure what you mean by supports open protocol. Hi, Great site. Many thanks. Hi Steve, Can Server and client share the port number, eg : Server is listening at port num : and client also listens on the same port num : Can you pls explain this. Both Google and Yahoo had different IP addresses. Leave a Reply Cancel reply Your email address will not be published.
Leave this field empty. On the other hand, if you are the remote user connecting to a web server it would work in reverse. Your web browser would pick a random TCP port from a certain range of port numbers, and attempt to connect to port 80 on the IP address of the web server.
When the connection is established, the web browser will send the request for a particular web page and receive it from the web server. Then both computers will disconnect the connection. Now, what if you wanted to run an FTP server, which is a server that allows you to transfer and receive files from remote computers, on the same web server. Therefore, the FTP server application when it starts will bind itself to TCP ports 20 and 21, and wait for connections in order to send and receive data.
Most major applications have a specific port that they listen on and they register this information with an organization called IANA. With developers registering the ports their applications use with IANA, the chances of two programs attempting to use the same port, and therefore causing a conflict, will be diminished. Every machine on the the Internet has a unique number assigned to it, called an IP address. Without a unique IP address on your machine, you will not be able to communicate with other devices, users, and computers on the Internet.
You can look at your IP address as if it were a telephone number, each one being unique and used to identify a way to reach you and only you.
Have you ever been connected to your computer when something strange happens? A CD drive opens on its own, your mouse moves by itself, programs close without any errors, or your printer starts printing out of nowhere? When this happens, one of the first thoughts that may pop into your head is that someone has hacked your computer and is playing around with you. Then you start feeling anger tinged The Internet is a scary place.
Criminals on the Internet have the ability to hide behind their computers, or even other peoples computers, while they attempt to break into your computer to steal personal information or to use it for their own purposes. To make matters worse, there always seems to be a security hole in your software or operating system that is not fixed fast enough that could With so much of Computer use these days revolving around the Internet and communicating with others, its important that you understand what exactly a network is.
Without networks, all communication between your computer and other computers whether it be instant messaging, email, web browsing, or downloading music could not be achieved. This tutorial will strive to teach you about networks and When using the Internet most people connect to web sites, ftp servers or other Internet servers by connecting to a domain name, as in www.
Internet applications, though, do not communicate via domain names, but rather using IP addresses, such as Therefore when you type a domain name in your program that you wish to connect to, your application must first convert How to make the Start menu full screen in Windows How to open an elevated PowerShell Admin prompt in Windows Not a member yet? Register Now. Introduction In this tutorial we will discuss the concept of Ports and how they work with IP addresses.
IP address with Ports This all probably still feels confusing to you, and there is nothing wrong with that, as this is a complicated concept to grasp. Users who read this also read:. Tracing a hacker Have you ever been connected to your computer when something strange happens? Understanding and Using Firewalls The Internet is a scary place.
All about Networks With so much of Computer use these days revolving around the Internet and communicating with others, its important that you understand what exactly a network is. The Hosts File and what it can do for you When using the Internet most people connect to web sites, ftp servers or other Internet servers by connecting to a domain name, as in www.
Tutorials Navigation. Latest tutorials. How to make the Start menu full screen in Windows 10 Lawrence Abrams.
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