Error: There is already an application listening for connections on port 80

DeployLX Network Licensing defaults to port 80 since most corporate and personal firewalls do not block that port increasing the probability that the user will be able to find and connect to the network license monitor without configuring anything. Other applications use the same reasoning and may already be listening on port 80. When the Network License Monitor starts you may receive the following error. 

There is already an application listening for connections on port 80


Other applications may try to use port 80 themselves. The most pervasive is Skype. By default when you install Skype it will listen on ports 80 and 443. This can interfere with the Network License Monitor. Skype does not need these ports and does not use them. The can be safely disabled with no ill effects.


Preventing Skype from Listening on Port 80

  1. Select Tools | Options
  2. Select the Advanced group
  3. Select Connection
  4. Uncheck Use port 80 and 443 as alternatives for incoming connections

Other Applications

If you aren't running Skype you can determine which application is using port 80 by running the following from the command prompt:

netstat -a -b -n -p TCP

NOTE: If you're running Windows Vista and later or Windows Server 2008 and later you will need to run netstat from an elevated command prompt

The output will be something like the following

Active Connections

Proto  Local Address          Foreign Address        State
 TCP                 LISTENING
  TCP                LISTENING
  TCP                LISTENING

The name of the executable appears in brackets following the line with the port number.

Published : Aug 13, 2009
Updated : Jan 04, 2012
Views : 28941
  • licensing
  • deploylx
  • error
  • network-licensing

Applies To

DeployLX Licensing v4.x