SSH (Customer Managed Key)

An SSH server is a combination of a specific SSH destination and the credentials to access it. This guide describes how to set up an SSH server with your own key in the Admin UI.

Prerequisites

Before you begin, you must ensure that the server you are attempting to add is accessible from the StrongDM relay or gateway. You must have a properly functioning relay up and running, and it must be able to reach the target server before you can proceed. Setting up a relay is out of the scope of this guide, but for more information, see Nodes.

Generate the Key

First generate your key. Use PEM or OpenSSH formatting to generate your key.

Note that if you use the AWS Secret Key Generator in Wizard mode to generate your key, this can cause issues due to the line breaks it inserts. We recommend that if you use this generator, you do so in plaintext.

Add a Server in the Admin UI

1. Log in to the Admin UI and select Resources > Servers.

2. Click the add server button.

3. On the Add Server dialog, select SSH (Customer Managed Key) as the Server Type and set other resource properties to configure how the StrongDM relay connects to the server via SSH.

   
4. Click create to save the resource.

Resource properties

Configuration properties are visible when you add a Server Type or when you click to view the server's settings. The following table describes the settings available for your SSH (Customer Managed Key) server.

Property	Requirement	Description
Display Name	Required	Meaningful name to display the resource throughout StrongDM; exclude special characters like quotes (") or angle brackets (< or >)
Server Type	Required	Select SSH (Customer Managed Key)
Proxy Cluster	Required	Defaults to "None (use gateways)"; if using proxy clusters, select the appropriate cluster to proxy traffic to this resource
Hostname	Required	Hostname or IP address to which you are connecting, such as testserver-01.example.org; relay server should be able to connect to your target server or hostname
Port	Required	Port to connect to the resource; default port value 22
Connectivity Mode	Required	Select either Virtual Networking Mode, which lets users connect to the resource with a software-defined, IP-based network; or Loopback Mode, which allows users to connect to the resource using the local loopback adapter in their operating system; this field is shown if Virtual Networking Mode enabled for your organization
IP Address	Optional	If Virtual Networking Mode is the selected connectivity mode, an IP address value in the configured Virtual Networking Mode subnet in the organization network settings; if Loopback Mode is the selected connectivity mode, an IP address value in the configured Loopback IP range in the organization network settings (by default, 127.0.0.1); if not specified, an available IP address in the configured IP address space for the selected connectivity mode will be automatically assigned; this field is shown if Virtual Networking Mode and/or multi-loopback mode is enabled for your organization
Port Override	Optional	If Virtual Networking Mode is the selected connectivity mode, a port value between 1 and 65535 that is not already in use by another resource with the same IP address; if Loopback Mode is the selected connectivity mode, a port value between 1024 to 64999 that is not already in use by another resource with the same IP address; when left empty with Virtual Networking Mode, the system assigns the default port to this resource; when left empty for Loopback Mode, an available port that is not already in use by another resource is assigned; preferred port also can be modified later from the Port Overrides settings
DNS	Optional	If Virtual Networking Mode is the selected connectivity mode, a unique hostname alias for this resource; when set, causes the desktop app to display this resource's human-readable DNS name (for example, k8s.my-organization-name) instead of the bind address that includes IP address and port (for example, 100.64.100.100:5432)
Secret Store	Optional	Credential store location; defaults to Strong Vault; to learn more, see Secret Store options
Authentication	Required	Select Leased Credentials (default) or Identity Aliases
Username	Required	Displays if Authentication is set to Leased Credentials and using StrongDM Secret Store; enter the username the relay should utilize to connect to the server via SSH (for example, bob.belcher)
Username (path)	Required	Displays if Authentication is set to Leased Credentials and using a non-StrongDM Secret Store; path to the secret in your Secret Store location (for example, path/to/credential?key=optionalKeyName where key argument is optional)
Identity Set	Required	Displays if Authentication is set to Identity Aliases; select an Identity Set name from the list
Healthcheck Username	Required	Displays if Authentication is set to Identity Alias; enter the username that will be utilized to verify StrongDM's connection to the server; username must exist on the target server
Private Key	Required	The key in either plaintext or Base64 encoding; paste the key or import the key
Allow Port Forwarding	Optional	When enabled, allows SSH connections proxied by StrongDM for this server to accept local forwarding requests; this checkbox is shown when the Allow port forwarding through SSH? option is turned on in the Admin UI security settings; see Port Forwarding for more information
Resource Tags	Optional	Resource Tags consisting of key-value pairs <KEY>=<VALUE> (for example, env=dev)

Secret Store options

By default, server credentials are stored in StrongDM. However, these credentials can also be saved in a secrets management tool.

Non-StrongDM options appear in the Secret Store dropdown if they are created under Settings > Secrets Management. When you select another Secret Store type, its unique properties display. For more details, see Configure Secret Store Integrations.

Identity Aliases and third-party Secret Stores

When you use Identity Aliases in combination with a third-party Secret Store, it is possible to provide different keys for different Identity Aliases. During server configuration, the Private Key (path) field, which specifies the path to the SSH private key in the Secret Store, can optionally include the variable $SDM_USERNAME. This variable is substituted with the user's Identity Alias when connecting to the resource. This allows a different SSH key to be used for different Identity Aliases connecting to the same resource.

For example, you could set Private Key (path) to path/to/credential/for/$SDM_USERNAME?key=ssh-key and store the keys for different users in the Secret Store under paths matching that pattern (path/to/credential/for/user1, path/to/credential/for/user2, ...path/to/credential/for/userN). This is optional. If the path you provide does not include the variable, the same SSH key is used for each user. This is only supported for third-party Secret Stores, as using the Strong Vault only allows a single key to be configured.

Add Your Key to Your Hosts

If you have not already, add your public key to the targeted host.

1. Open a command prompt on the server you are adding and edit the authorized keys file for the user specified during server setup.

    sudo vi ~/.ssh/authorized_keys

2. Append the generated public key to the end of the file, save, and exit.

3. Back in the Admin UI, go to the Servers section and click the server's name to view status, diagnostic information, and setting details.

4. In the server settings, click the Update button.

The Admin UI displays that resource as unhealthy while the configuration is being applied. When the resource is ready, the Health icon indicates a positive, green status.