I'm tuning up the Windows Advanced Firewall on my web server. All I need is 80 (HTTP), 443 (HTTPS) and 808 (net.tcp). I noticed that I needed to create a rule for 80 and 443 before my application would work, but not for 808. In fact, it wasn't until I created a specific rule to block 808 that my application stopped working.

Can anyone explain why I needed a specific rule to block 808 before it would stop traffic?


Short answer: Port 808 is used by the Net.TCP Port Sharing service, associated with Internet Information Services through the Windows Communication Foundation. Without it, IIS generally will not work.

Long Answer:

Port 808 is used by the Net.TCP Port Sharing service, associated with the Windows Communication Foundation. Windows Communication Foundation (WCF) is a framework for building service-oriented applications.

Port Sharing is commonly used by network applications that utilise the HTTP protocol as it is (on most networks) allowed by default.

A few examples in which WCF may be used are:

  • A secure service to process business transactions.
  • A service that supplies current data to others, such as a traffic report or other monitoring service.
  • A chat service that allows two people to communicate or exchange data in real time.
  • A dashboard application that polls one or more services for data and presents it in a logical presentation.
  • Exposing a workflow implemented using Windows Workflow Foundation as a WCF service.
  • A Silverlight application to poll a service for the latest data feeds.

"Many network applications make use of the HTTP protocol because most firewalls are configured by default to allow traffic on TCP port 80."

Therefore, Microsoft needed to implement a way to allow multiple applications running through IIS to share the same port, thus the concept of Net.TCP Port Sharing was born.

Note: I sourced this information through my own research. If you require a more detailed explanation as to how I gathered this information and came to this info, please do feel free to send me a private message and I will be more than happy to explain in detail.


Port 808 is the Microsoft Net.TCP Port Sharing Service.

"Windows Communication Foundation (WCF) provides a new TCP-based network protocol (net.tcp://) for high-performance communication. WCF also introduces a new system component, the Net.TCP Port Sharing Service that enables net.tcp ports to be shared across multiple user processes."


  1. List of TCP and UDP port numbers, https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers, accessed 24 December 2016.
  2. Net.TCP Port Sharing, https://msdn.microsoft.com/en-us/library/ms734772(v=vs.110).aspx, accessed 24 December 2016.
  • 1
    This is a question about the firewall. How is this answer remotely related to the original question? – Donald Airey Dec 24 '16 at 14:50
  • Please read the question again carefully. Your answer does not answer the original question. – DavidPostill Dec 24 '16 at 17:07
  • @MikeDoonsebury, I did my best to answer it. I revised it today to provide a more detailed response which may provide some clarity. If you feel that I have answered your question, please do upvote it. But I would reconsider the used of the word "remotely" which could imply that I do not know what I am talking about. – Christopher Hawker Dec 25 '16 at 10:42

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