Port 80 in already in use

By Skyjob ·

I have been given the delightful task to monitor and support an online/offline training program for staff.

The program uses local web server technology to enable students to access the asp pages used.

It advises students to close all messenger applications and other servers on their machines prior to running the offline module, which is the most useful one.

Unfortunately a lot of users are faced with the message "Port 80 is already in use", but are unable to determine what is using port 80.

Can anyone assist in an easy method of determining what application is using or blocking port 80 so my students can complete their course work?

The software is only supporting the Windows operating environment and is used by the students on their own hardware.

Many thanks

This conversation is currently closed to new comments.

Thread display: Collapse - | Expand +

All Answers

Collapse -

A quick glance at the IANA doco

by Tig2 In reply to Port 80 in already in use

Indicates that Port 80 is the web.

http 80/tcp World Wide Web HTTP
http 80/udp World Wide Web HTTP
www 80/tcp World Wide Web HTTP
www 80/udp World Wide Web HTTP
www-http 80/tcp World Wide Web HTTP
www-http 80/udp World Wide Web HTTP

You can find the complete listing here:

Hope this helps!

Collapse -

try Nstat

by DanLM In reply to Port 80 in already in use

here is a link to a quick tutorial on using nstat on windows, which will list the ports that are in use and what is using them.

Hope this helps.


Collapse -

XP or 2000 workstations?

by lowlands In reply to Port 80 in already in use

It is most likely that IIS is installed on the workstations.

On XP workstations it is pretty simple to figure out what application has a port open.

From the command line run <b>netstat -ano | findstr "80"</b>. This should give you at least one line with the pc's ip or loopbackaddress and at the end is a process ID. Use for example task manager to find the process name that corresponds to the Process ID.

Collapse -

Here is the soln

by tuppisau In reply to Port 80 in already in use

For troubleshooting why the Web App Server says the port is in use...

Windows XP and 2003 have the tools built-in to determine what process is using a specific TCP/IP port. If you are using some other version of windows, you will not be able to continue as below. But there are still a number of third-party tools available which can be downloaded instead. One such tool that has been used successfully by several people is fport.

From a command prompt, run netstat -o. This will output a list of ports, along with the PID (process ID) that has that port open. The output looks something like:


C:\Documents and Settings\Administrator>netstat -o

Active Connections

Proto Local Address Foreign Address State PID

C:\Documents and Settings\Administrator>

The sample output above indicates that the local port 80 is being used by process id 2636.

To determine what executable is running as a process ID, open Windows Task Manager and switch to the Processes tab. Now click on View->Select Columns... On the screen that opens, make sure "PID (Process Identifier)" is checked and then click OK. Now click on the PID heading to sort the entries by PID. The screen below shows that PID 2636 is alpha5.exe, indicating that it is the Web Application Server using port 80 in this case.

Let me know if it helped

Collapse -

Problem solved, thanks so much

by wangqind In reply to Here is the soln

I followed your instruction, and it all works now. Thanks a looooot!

Collapse -

hi there..

by rippletank85 In reply to Port 80 in already in use

I was actually browsing to find something else and here I came with your question. lol

The easiest way I would say is to run netstat -n command in command line. It will show you the the links they are establishing between local hosts and destination and the port they are using.

Collapse -

An option if you do not like

by Dumphrey In reply to Port 80 in already in use

Related Discussions

Related Forums