Update .NET web service to use TLS 1.2

c# .net tls1.2
nasch picture nasch · Jul 28, 2017 · Viewed 195.3k times · Source

I need to use TLS 1.2 to connect from my .NET web service to another that is going to force TLS 1.2. I found a resource that said .NET 4.6 uses TLS 1.2 by default so that sounded like the easiest solution. I updated the .NET framework on the server and restarted. In IIS I tried to make an application pool using .NET 4.6 but 4.0 was the only option. Then I found something that said it would still say 4.0 because 4.6 is an "in place" update to .NET 4.0. So I thought maybe I was done. However on an error page that I got for unrelated reasons, it said Microsoft .NET Framework Version:4.0.30319 so it seems I have not successfully upgraded. Any pointers on how to make sure my application pool is using .NET 4.6, or more generally how to enable TLS 1.2?

Answer

Etienne Faucher picture Etienne Faucher · Aug 1, 2017

We actually just upgraded a .NET web service to 4.6 to allow TLS 1.2.

What Artem is saying were the first steps we've done. We recompiled the framework of the web service to 4.6 and we tried change the registry key to enable TLS 1.2, although this didn't work: the connection was still in TLS 1.0. Also, we didn't want to disallow SLL 3.0, TLS 1.0 or TLS 1.1 on the machine: other web services could be using this; we rolled-back our changes on the registry.

We actually changed the Web.Config files to tell IIS: "hey, run me in 4.6 please".

Here's the changes we added in the web.config + recompilation in .NET 4.6:

<system.web>
    <compilation targetFramework="4.6"/> <!-- Changed framework 4.0 to 4.6 -->

    <!--Added this httpRuntime -->
    <httpRuntime targetFramework="4.6" />

    <authentication mode="Windows"/>
    <pages controlRenderingCompatibilityVersion="4.0"/>
</system.web>

And the connection changed to TLS 1.2, because IIS is now running the web service in 4.6 (told explicitly) and 4.6 is using TLS 1.2 by default.

Related questions

Is TLS 1.1 and TLS 1.2 enabled by default for .NET 4.5 and .NET 4.5.1?

On our Windows 2012 Server R2, we need to disabled TLS 1.0. However we have .NET 4.5 Wcf services running. We found that if we disable TLS 1.0 that the WCF services no longer run, as we get the error 'An existing connection was …

Read More
System.Net.SecurityProtocolType.Tls12 definition not found

I'm trying to add the following line of code to the Global.asax file in a website project. System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12; The vs2012 IntelliSense is showing that Tls12 definition exist. But the build is saying …

Read More
TLS 1.2 not negotiated in .NET 4.7 without explicit ServicePointManager.SecurityProtocol call

I need to upgrade a .NET application to support a call to an API on a website that only supports TLS 1.2. From what I read, if the application is targeting 4.6 or higher then it will use TLS 1.2 by default. To …

Read More