Setting the Certificate Checking Mode in Horizon Client

Server certificate checking occurs for connections between Horizon Client and a server. A certificate is a digital form of identification, similar to a passport or a driver's license.

About Certificate Checking

Server certificate checking includes the following checks:

• Is the certificate intended for a purpose other than verifying the identity of the sender and encrypting server communications? That is, is it the correct type of certificate?
• Has the certificate expired, or is it valid only in the future? That is, is the certificate valid according to the computer clock?
• Does the common name on the certificate match the host name of the server that sends it? A mismatch can occur if a load balancer redirects Horizon Client to a server that has a certificate that does not match the host name entered in Horizon Client. Another reason a mismatch can occur is if you enter an IP address rather than a host name in the client.
• Is the certificate signed by an unknown or untrusted certificate authority (CA)? Self-signed certificates are one type of untrusted CA. To pass this check, the certificate's chain of trust must be rooted in the device's local certificate store.

For information about distributing a self-signed root certificate that users can install on their client devices, and instructions for installing a certificate on an Android or Chromebook device, see the documentation for the device.

How to Set the Certificate Checking Mode

A system administrator might ask end users to set the certificate checking mode in Horizon Client to make sure that they can successfully connect to a server. At some companies, an administrator might set the certificate checking mode and prevent end users from changing it in Horizon Client.

To set the certificate checking mode, start Horizon Client, tap the Settings (gear) icon in the upper-right corner of the Horizon Client window, tap Security options, and tap Security mode. You can select one of the following options.

• Never connect to untrusted servers. This setting means that you cannot connect to the server if any of the certificate checks fail. An error message lists the checks that failed.
• Warn before connecting to untrusted servers. This setting means that you can click Continue to ignore the warning if a certificate check fails because the server uses a self-signed certificate. For self-signed certificates, the certificate name is not required to match the server name that you entered in Horizon Client. You can also receive a warning if the certificate has expired.
• Do not verify server identity certificates. This setting means that no certificate checking occurs.

If an administrator later installs a security certificate from a trusted certificate authority and all certificate checks pass when you connect, this trusted connection is remembered for that specific server. In the future, if that server ever presents a self-signed certificate again, the connection fails. After a particular server presents a fully verifiable certificate, it must always do so.