Unable to launch the asp.net development server because port '80' is in use

Question

I need to use port 80 for my development server. Before i restart pc, it's still working fine. After that, it pop up the port 80 is in use. The development server able to run if i changed to other port.

I've checked using netstat -ano, no program is using it (my iis is using other port and my skype is not using port 80 as well). I also test with telnet localhost 80, it didnt show any failure message, just the screen goes blank...I'm using win xp. Is my visual studio has problem?

Answer 1

Port 80 is a reserved port number, for HTTP traffic. http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers

Why exactly do you need to use port 80?

Answer 2

If your telnet window goes blank when you telnet to 80, then something is already listening on that port.

Answer 3

Things i have done.

1. Check it with netstat -ano and TcpView, both did not show port 80 is in use.
2. Try to connect it via telnet (telnet localhost 80). The screen goes blank, but when i press any key, the screen back to command prompt. As Lerxst said, screen goes blank meaning the port is occupied but i can't find any program is listening it.
3. I have skype installed, but it has turned off using port 80.
4. I have SQL 2008 installed, but i has turned off Integration & Reporting Services which may use port 80.
5. Changed my iis default port number to 8888 and even turn off the service.
6. I have XAMPP installed but i have turned off it.
7. I tried to turn off firewall as well, but still the same.

Answer 4

If you use Skype, then Skype reserves port 80 as an alternative port (disable in Skype settings). I had this happening to me several times.