Remote Desktop Gateway is a Remote Desktop Services server role. This role allows authorized remote users to connect to resources located on an internal or private network from any Internet-connected device. The accessible resources can be terminal servers, remote applications, remote desktops, and so on.
The Remote Desktop Gateway Server Protocol is a remote procedure call (RPC) protocol using HTTPS as the transport mechanism, used primarily for tunneling client to server traffic across firewalls. The One Identity Safeguard for Privileged Sessions (SPS) can act as a Remote Desktop Gateway, receiving connections using the Remote Desktop Gateway Server Protocol and transferring them to the target servers using the RDP protocol.
The Remote Desktop Gateway Server Protocol enables inband destination selection, meaning that SPS can extract the address of the target server from the client connections. This greatly simplifies managing connections on SPS without having to encode the name of the target server in the username, which was problematic as the length of the username is limited on many platforms — especially in non-transparent mode.
To access remote servers using a Remote Desktop Gateway, the clients must use version 6.1 or newer of the Remote Desktop application. Note that officially only version 6.0 is available for the Windows 2003 Server operating system, though it is possible to install a newer version. However, this is a problem only when initiating RDP connections from the Windows 2003 Server host, not when the Windows 2003 Server is the target of the connection.
SPS must be a member of a Windows Domain (for details on joining a domain, see Network Level Authentication (NLA) with domain membership), or you must use a Local User Database (for details, see Creating a Local User Database).
Ensure that the system times of the Domain Controller, the target servers, the clients, and SPS are synchronized.
Gateway authentication on the SPS web interface cannot be used for connection policies that use SPS as a Remote Desktop Gateway. However, the Remote Desktop applications of the clients can be configured to perform two separate authentications, one on the Remote Desktop Gateway (that is, on SPS), and one on the target server. For details on configuring the Remote Desktop applications of the clients to perform gateway authentications, see Configuring Remote Desktop clients for gateway authentication.
The Remote Desktop Gateway Server Protocol supports various authentication methods. SPS acting as a Remote Desktop Gateway supports only NTLM authentication.
SPS can be used as a Remote Desktop Gateway. The terminal service clients must be configured to use SPS as the Remote Desktop Gateway. SPS will connect the server (selected inband) after authentication.
Remote Desktop Gateway will require a certificate. Decide whether you want to use a fix certificate, or an on-the-fly generated certificate before performing the steps below and prepare the certificate.
You may also need to adjust the port settings of the connections. The default port for RDP connections is 3389, but the Remote Desktop Gateway Server Protocol uses port 443. However, the SPS web interface uses port 443 as well, and other connection policies might already use port 443. Therefore, if administrator or user login is enabled on the interface that receives the Remote Desktop Services connections, add a new alias IP address to the interface of SPS and use this alias in your connection policy and the client configurations. For details on creating IP aliases on SPS, see Managing logical interfaces.
When the client uses hostname in inband destination selections, the hostname must comply with RFC5890: Internationalized Domain Names for Applications (IDNA). For example, from the ASCII characters only letters, digits, and the hyphen character is permitted.
Starting with version 6.1.0, SPS rejects connection requests where the hostname does not comply with RFC5890.
To use SPS as a Remote Desktop Gateway
Navigate to RDP Control > Connections and create a new connection policy that will handle the incoming client connections that use the Remote Desktop Gateway Server Protocol.
Enable the Act as a Remote Desktop Gateway option.
Figure 210: RDP Control > Connections — Configuring SPS as a Remote Desktop Gateway (or RD Gateway)
Set the target of the connections.
To direct every incoming connection to a single target server, select Use fixed address and specify the address of the target server.
To extract the destination address from the Remote Desktop Gateway Server Protocol, select Inband destination selection and set the address of the servers the clients are allowed to access in the Target > Domain fields. For details on using inband destination selection, see Modifying the destination address.
NOTE: In non-transparent mode, enter the IP address generated for the Remote Desktop Gateway service into the To field. Do not enter the IP address configured for administrator or user login.
To act as a Remote Desktop Gateway, SPS needs to display a certificate to the clients.
To display always the same certificate, select Use the same certificate for every connection and upload the X.509 certificate and the matching private key.
One Identity recommends using 2048-bit RSA keys (or stronger).
The Common Name (CN) of the certificate must be the FQDN of SPS, which is the address of the Remote Desktop Gateway specified in the client applications. Otherwise the clients will reject the connections.
To automatically create new certificates on SPS for every client, select Generate certificate on-the-fly, then select the Certificate Authority (CA) to sign the generated certificates with from the Signing CA field. For details on creating a signing CA, see Signing certificates on-the-fly.
By default, the Common Name (CN) of the generated certificate is <SPS-hostname.domainname>. You can set a custom Common Name in the Custom Common Name field.
NOTE: Save the CA certificate used to sign the certificate that SPS shows into DER format and import it to the clients into the Local Computer > Trusted Root Certificate store of the clients so that the clients can verify the identity of SPS.
Under Authentication backend:
To use Active Directory for authentication, select Active Directory.
To use a Local User Database for authentication, select Local User Database, enter the Domain, and select the Local User Database from the list.
Configure other parameters of the connection policy as needed for your environment.