From time to time I have to open a port to do something and close it back up when I'm done. As I do this fairly often (but not often enough to memorize) I created this recipe. There is an example using Docker below.
ugh! an error! what to do?
Background Information...
How to do this by the Windows user Interface (UI)
https://www.google.com/search?q=windows+10+firewall+enable+localhost%3A80+traffic
How to do this with Powershell
https://www.google.com/search?q=powershell+TCP+Port+80+in+Windows+Firewall
https://docs.microsoft.com/en-us/powershell/module/netsecurity/new-netfirewallrule?view=win10-ps
https://serverfault.com/questions/883266/powershell-how-open-a-windows-firewall-port
Powershell
Open the port
New-NetFirewallRule -DisplayName "Allow inbound TCP port 81" -Direction inbound -LocalPort 81 -Protocol TCP -Action Allow
Name : {af16f2f3-3221-4191-8c5a-f44a5f60ca58}
DisplayName : Allow inbound TCP port 81
Test (while something is listening on the port)
Get-NetFirewallRule -Name '{af16f2f3-3221-4191-8c5a-f44a5f60ca58}'
** You can also see this in the Windows firewall inbound rules
$tcp = New-Object System.Net.Sockets.TcpClient
$tcp.Connect("localhost","81")
$tcp.Connected
True
Close the port back up
** If you test again, you should get a failure (or, your listening port was not blocked already). And, the control panel, on refresh, will show the rule is missing.
You're done!
Example
As a semi-practical example, Start a Docker container, test and clean up. For this to be a real example, you would have to imagine that port 81 was the blocked port. On port 80, I got stuff running there already. So, I did this on port 81.
Open the Port
Start the getting-started container
6d44c9240e688b69a212fe24e58d2302b658bfcbcee787030943b04f12cde38b
Test that the container is running and on the proper port.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
6d44c9240e68 docker/getting-started "/docker-entrypoint.…" 6 seconds ago Up 4 seconds 0.0.0.0:81->80/tcp goofy_elion
Test the port via Powershell
(New-Object System.Net.Sockets.TCPClient –Argument "localhost","81").Connected
True
Open page in local browser http://localhost:81
Hooray! It works! : )
Clean up the container
6d44c9240e68
