Hi everyone! It has been awhile since I have posted here. Mostly because I have not run into any frustrating issues recently. However this problem really racked my brain until I figured it out.
I was troubleshooting an issue where connecting to a site using any of the PowerShell commands to get web data triggered an error like this:
“The underlying connection was closed: An unexpected error occurred on a receive”
Whereas accessing the site in a web browser worked just fine! Puzzling, right?!
After doing a packet capture and analyzing the traffic, it was apparent that the TLS handshake never began. The TCP handshake was occurring, but nothing after that.
I spent some time going down the rabbit hole of checking the registry’s SCHANNEL settings for SSL & TLS. Sure enough, SSL 1.0 – 3.0 and TLS 1.0 were disabled, per good security hardening measures. RC4 was also disabled, but I wouldn’t expect that cipher to be used for websites’ HTTPS.
To make a long story short, the issue is that older versions of DOTNET framework (i.e. 3.5 and 4.0) do not inherently support the newer versions of TLS like 1.2 and 1.3. You must manually enable them by puttin in regkey settings that tell DOTNET to respect the system-level settings defined in the SCHANNEL hive.
Those settings look like this:
You will want to reboot to ensure the settings get applied.
Note that the newer versions of DOTNET don’t require these registry keys in order to support TLS 1.1 – 1.3, it should work automatically.
As always, test you your changes in a lab because you don’t know what might break whenever you change the smallest item.
More information from Microsoft regarding SSL/TLS can be found here: https://docs.microsoft.com/en-us/dotnet/framework/network-programming/tls
Bonus: if you need to list all versions of dotnet installed on a system, then run this in Powershell:
Get-ChildItem ‘HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP’ -Recurse | Get-ItemProperty -Name Version, Release -ErrorAction 0 | where { $_.PSChildName -match ‘^(?!S)\p{L}’} | select PSChildName, Version, Release | FL
Never A Null Moment 