구 닷넷프레임워크 버전에서 TLS1.2 사용 절차
System.Net.SecurityProtocolType.Tls12 definition not found
1.서버TLS1.2활성화
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server
Enabled (DWORD): 1
DisabledByDefault (DWORD): 0
2.C#
System.Net.ServicePointManager.SecurityProtocol = (System.Net.SecurityProtocolType)(0xc0 | 0x300 | 0xc00);