security issue nodejs port 4000 - node.js

I am running nodejs (express framework) on port 3000 and works fine. Accidentally, I ran the program on port 4000 and I saw all of my data could be revealed like ftp. the interesting part is that just for port 4000 this happens and in my app I am just listening on port 3000
http://localhost:4000
result:
enter image description here

Related

What does the localhost: 3000 server created by express mean?

What is it that you access when you type in "localhost: 3000" onto your browser? What does that represent?
localhost is a special domain name that always refers to your local computer.
3000 is a tcp port. When you open a url such as:
http://localhost:3000/
Then a connection will get opened to port 3000.
When you specify a url like:
http://localhost/
Then you will open port 80, because the default HTTP port is 80
localhost:3000 is a local development server running on port 3000 of your computer. It is created by the express and can render html pages and route the apis for different requests. With the expressjs framework you can create different routes and associate it with the development or production port. You can also change the port during the development which can be done by changing the value of listening port on your app/index/server .js file.

how to allow access to port on AWS

I am trying to connect to my development port port 3000 on aws but it is not working. I have currently configured my domain with the instance and it is working fine but I cannot access port 3000 and get ERR_EMPTY_RESPONSE
The security group setting is as below
As you can see, I have opened up my mongo port 27017 and 3000 which is my node server port
As you can see here, it is listening at port 3000. I set it to print out the exact port that is being listened.
When I go netstat -natlp the following shows
port 3000 is currently listening.
I have followed all the instructions and suggestions but it is still not working for a weird reason. The server I use is Asia(Seoul) server.
Am I missing something here?

Meteor always listens on port 3000

I created a new Meteor project in WebStorm on Windows 8.
In "Run/Debug Configurations" I set the port value to 3008, but when I run the app, it always works on port 3000.
Does anybody know where Meteor defines the port number or how can I change it?
I've searched the words "3000", "PORT" and "listen" in the entire project but they don't exist.
I've also seen these questions which didn't help me because they use Express which defines the port number hard-coded:
Node.js/Express.js App Only Works on Port 3000 ,
Express is listening on port 3000 despite setting it to 80?
Any help will be profoundly appreciated!
Try passing -p 3008 as a program argument in Meteor run configuration:
http://localhost:3008 in Browser/Live Edit tab is just used for browser launching (i.e. it tells WebStorm to launch the browser with specified URL), it's not supposed to affect Meteor port in any way

run multiple apps on different ports in nodejs express framework

I am running an application using node.js express framework on port 3000 (http://localhost:3000) in my windows machine. Also i want to run another(second) application on different port say like 3005 or 8080 etc. In my first application i didn't specified any port number and i believe expressjs by default runs on port 3000. But in second app i mentioned port number app.listen(8080) in my app.js. When i tried to start second application am getting port 3000 is already in use error. So i stopped first appliction and then only i can run second application and also it is running on both 3000 and 8080 ports. I didn't understand why it is still running on 3000 still i specified port 8080 number in app.js.
Could any one help to run both application on different ports in same instance
Thanks
If you're using express generator also check the www file in the bin folder, which probably contains a part similier to this:
var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);
Change the '3000' part to the port you desire and it should run as intended.
Lastly to change port use "PORT=4000 node app/app.js" in cmd line.
Port no can be changed to any other port no. 5000,6000 etc ...
i believe expressjs by default runs on port 3000
It's true, but you can change it.
I think you run express default boilerplate app.
In this case you should update line var port = normalizePort(process.env.PORT || '3000'); in bin/www.
It worked after changing port number in www file. www file is located in bin folder that was created during enviornment setup.

Node.js + Express only work on port 3000 on test server

On Local Test it work. on different port (3001, 8080)
But on Test Server (Azure)
I run 2 instance of Node App on same machine
$ node api1/index.js (on port 3000)
$ node api2/index.js (on port 3001)
and
$ node api1/index.js (on port 3001)
$ node api2/index.js (on port 3000)
But it only works on port 3000.
How do I set different port in Express?
Now, I've changed at app.listen(3001) on index.js and it doesn't work.
Often cloud platforms set an environment variable that contains the port they want you to stick your app on. I don't have any experience with Azure... See the answer here: How to run a node.js server on Azure?
Specifically:
var port = process.env.port
Most cloud providers in my experience don't let you play on other ports. You can always specify a localhost port too, though by doing this:
var port = process.env.port || 3001 //(or whatever)
app.listen(port);
this way if process.env.port is undefined (which it will be in your dev environment) you fallback to 3001.
Make sense?

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