System.Net.SecurityProtocolType.Tls12 definition not found

c# .net ssl tls1.2
HockChai Lim picture HockChai Lim · Nov 13, 2017 · Viewed 47.4k times · Source

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 that the definition does not exist (See screen shot).

screen shot

I've tried adding System.Net.dll to the bin folder of the project, but the build still failed. Any idea how I might be able to resolve this?

Answer

figolu picture figolu · Jul 15, 2018

SecurityProtocolType.Tls11 and SecurityProtocolType.Tls12 enum values are missing on Framework 4.0 only.

SecurityProtocolType numeric values:
SystemDefault (0)
Ssl3 (48 - 0x30)
Tls (192 - 0xC0)
Tls11 (768 - 0x300) missing on Framework 4.0
Tls12 (3072 - 0xC00) missing on Framework 4.0

On Framework 4.0, if want to allow TLS 1.0, 1.1 and 1.2, just replace:

SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12

by:

(SecurityProtocolType)(0xc0 | 0x300 | 0xc00)

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
SSL and Outdated TLS(1.0 and 1.1) for Web Service client application on .Net 3.5

As per PCI, we need to stop using SSL and TLS(1.0 and 1.1 in certain implementation) from June 30th 2016 as per http://blog.securitymetrics.com/2015/04/pci-3-1-ssl-and-tls.html We have an client application build on .Net 3.5 which uses HttpWebRequest object …

Read More
Can't get SslStream in C# to accept TLS 1.2 protocol with .net framework 4.6

I have made a program that is supposed to accept an SSL connection. I want it to only accept TLS 1.2 to increase security. To do this I have installed .net framework 4.6 and compiled the SW, using Visual studio 2015 express on …

Read More