Unable to connect DS Out-of-Office to Exchange

I am unable to connect the Out-of-Office (DSOF) to my Exchange 2016 server. When I choose to add End-Point and fill the dialog with username and password and click Okay, I just get "establishing a secure TLS/SLL channel failed".

On further investigation I find that we have disabled the TLS1.0 + 1.1 protocol on our Exchange server, just like Microsoft advised recently. Office 365 is also soon going to move to 1.2 only.

Do you have an update to your product?

Answer:

TLS is happening at the transport layer of .NET. So it is not something that is controlled by DynamicSignature. So you should ensure that the machine you installed DSOF on supports TLS1.2. Below is a copy of an article written by Microsoft that guide you to enable TLS1.2 in both the OS and .NET.

Reboot is required.

 

Exchange Server TLS guidance Part 2: Enabling TLS 1.2 and Identifying Clients Not Using It

 
By
The_Exchange_Team
Published Apr 02 2018 10:11 AM
 

Overview

In part 2 of our Exchange Server TLS Guidance series we focus on enabling and confirming TLS 1.2 can be used by your Exchange Servers for incoming and outgoing connections, as well as identifying any incoming connection which is not utilizing TLS 1.2. The ability to identify these incoming connections will vary by Windows Server OS version and other factors. Part 2 will not cover disabling TLS 1.0 or TLS 1.1, nor disabling older cipher suites from being used. Part 3 of the TLS guidance series will go into detail on those topics.

Assumption

For Part 2 of our TLS guidance series we assume you have already audited your on-premises Exchange Servers and applied all updates called out in Part 1: Getting Ready for TLS 1.2. Please perform the activities called out in part 1 if you have not prior to moving forward with any configurations outlined in part 2.

Enabling TLS 1.2

The method used to enable TLS 1.2 varies by the version of the Windows Server operating system. Some versions of Windows Server have TLS 1.2 enabled by default while others do not. Our steps will, regardless of the OS’ default state, configure TLS 1.2 so it is enabled and available for incoming (Server) connections and outgoing (Client) connections. From part 1 you should be familiar with the various components Exchange Server relies on such as Schannel, WinHTTP and .NET. Unless stated otherwise the same registry paths are used across all supported Windows Server operating systems.

Enable TLS 1.2 for Schannel

All Windows Server versions

TLS protocols are enabled or disabled in Windows Schannel by editing the Windows Registry. Each protocol version can be enabled or disabled independently. You don't need to enable or disable one protocol version to enable or disable another protocol version. The Enabled DWORD registry value defines whether the protocol version can be used. If the value is set to 0, the protocol version cannot be used, even if it is enabled by default or if the application explicitly requests that protocol version. If the value is set to 1, the protocol version can be used if enabled by default or if the application explicitly requests that protocol version. If the value is not defined, the operating system’s default value will be used. We recommend configuring the value to have a consistent state across your servers. The DisabledByDefault DWORD registry value defines whether the protocol version is used by default. This setting only applies when the application doesn't explicitly request the protocol versions to be used. If the value is set to 0, the protocol version will be available for use by default. If the value is set to 1, the protocol version will not be available for use by default. If the value is not defined, the operating system’s default value will be used. We recommend configuring the value to have a consistent state across your servers. For example; consider what would happen if TLS 1.2’s values were set to a combination of Enabled and DisabledByDefault both set to a value of 1. In this example an application could only use TLS 1.2 if the application specifically called for TLS 1.2. If the application did not specifically call for TLS 1.2, then it would not be able to use TLS 1.2 as even though the protocol is enabled, it is not in the default list of available protocols. To enable TLS 1.2 for both server (inbound) and client (outbound) connections on an Exchange Server please perform the following.

  1. From Notepad.exe, create a text file named TLS12-Enable.reg.
  2. Copy and paste the following text into the file.

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2]
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client]
"DisabledByDefault"=dword:00000000
"Enabled"=dword:00000001
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server]
"DisabledByDefault"=dword:00000000
"Enabled"=dword:00000001

  1. Save TLS12-Enable.reg.
  2. Double-click the TLS12-Enable.reg file.
  3. Click Yes to update your Windows Registry with these changes.
  4. Restart the machine for the changes to take effect.

Enable TLS 1.2 for .NET 3.5

This step is only required for Exchange Server 2010 installations where .NET 3.5 is relied upon. Exchange Server 2013 or later installations may skip this step unless you have additional applications on the server utilizing .NET 3.5 which must be able to use TLS 1.2. The SystemDefaultTlsVersions registry value defines which security protocol version defaults will be used by .NET Framework 3.5. If the value is set to 0, then .NET Framework 3.5 will default to using SSL 3.0 or TLS 1.0. If the value is set to 1, then .NET Framework 3.5 will inherit its defaults from the Windows Schannel DisabledByDefault registry values. If the value is undefined, it will behave as if the value is set to 0. By configuring .NET Framework 3.5 to inherit its values from Schannel we gain the ability to use TLS 1.2.

  1. From Notepad.exe, create a text file named NET35-UseSchannelDefaults.reg.
  2. Copy, and then paste the following text.

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v2.0.50727]
"SystemDefaultTlsVersions"=dword:00000001

  1. Save the NET35-UseSchannelDefaults.reg file.
  2. Double-click the NET35-UseSchannelDefaults.reg file.
  3. Click Yes to update your Windows Registry with these changes.
  4. Restart your computer for the change to take effect.

Enable TLS 1.2 for .NET 4.x

This step is only required for Exchange Server 2013 or later installations where .NET 4.x is relied upon. The SystemDefaultTlsVersions registry value defines which security protocol version defaults will be used by .NET Framework 4.x. If the value is set to 1, then .NET Framework 4.x will inherit its defaults from the Windows Schannel DisabledByDefault registry values. If the value is undefined, it will behave as if the value is set to 0. By configuring .NET Framework 4.x to inherit its values from Schannel we gain the ability to use the latest versions of TLS supported by the OS, including TLS 1.2.

  1. From Notepad.exe, create a text file named NET4X-UseSchannelDefaults.reg.
  2. Copy, and then paste the following text.

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001

  1. Save the NET4X-UseSchannelDefaults.reg file.
  2. Double-click the NET4X-UseSchannelDefaults.reg file.
  3. Click Yes to update your Windows Registry with these changes.
  4. Restart your computer for the change to take effect.

Note: When configuring a system for TLS 1.2, you can make the Schannel and .NET registry keys at the same time and reboot the server once.

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