Question: * I have encountered a weird error while setting up the `FTP` for my Windows Server 2008 R2.
* After finishing the setting up of the FTP, I tried starting it, as it was `OFF` by default whereas I think it should be started by default.

![After setting up FTP](https://i.stack.imgur.com/HNnnD.png)

* On trying to start this FTP, I encountered an error saying "FTP cannot be started. Another FTP site may be using the same port".

![On trying to start the FTP](https://i.stack.imgur.com/mrrH9.png)

* As there is not another FTP site other than this one, I can't figure it out.
* I tried `netstat -a`, and found out that the port number **21 is already listening**, but I **don't see** any FTP site running on my `IIS console`.

![enter image description here](https://i.stack.imgur.com/gM3XY.png)

* Can anyone please help me out as to how to resolve this problem or at least let me know how to stop the service which is listening at port 21 so it stops listening. Then I can set this current FTP site to listen on port 21.

Answer: 
You can use the `netstat -anb`command to see which process is listening on port 21.

Be sure to run that from an elevated command-line.

**Edit**: For clarification, here is what the `-anb` option does:

* `a` Displays listening ports as well as open connections
* `n` Doesn't attempt to resolve host names and port numbers (makes it much faster)
* `b` Tries to display the process associated with each specific socket.
If something else is using the port and you need it to still run or can't change it you can bind the FTP site to another IP address and use the FTP port on that IP address

Open IIS Manager. In the Connections pane, expand the Sites node in the tree, and then click to select the site for which you want to add a binding.In the Actions pane, click Bindings.
In the Site Bindings dialog box, click Add. In the Add Site Binding dialog box, add the binding information and then click OK

Think you may need to download the FTP Server through Web Installer to be able to do this for FTP sites.