How to Use the Command 'nmcli agent' (with examples)

The nmcli agent command is a powerful tool used in Linux environments to interact seamlessly with NetworkManager as a secret or polkit agent. nmcli helps manage network connections and settings directly from the command line, and when used as an agent, it disciplines how requests for secrets (like passwords) and authorizations are handled systematically. This adds an extra layer of control and automation in environments where network management tasks are a routine operation.

Use case 1: Register nmcli as a secret agent and listen for secret requests

Code:

nmcli agent secret

Motivation:

In various scenarios, especially in server environments, it’s critical to ensure that network interactions requesting sensitive information such as passwords are handled securely and efficiently. Running nmcli as a secret agent allows it to catch and respond to secret requests that NetworkManager may require during the establishment or management of network connections. This use case is vital as it abstracts the manual entry of credentials, promotes security, and minimizes human errors in environments managing numerous networks.

Explanation:

• nmcli: This is the command-line interface of NetworkManager used for controlling network settings and connections.
• agent: This potent subcommand allows for executing agent-related tasks, such as handling secrets or authentication requests.
• secret: This specific argument registers nmcli as a secret agent, thus enabling it to handle and process requests related to sensitive information, such as credentials, passed by NetworkManager.

Example Output:

Upon executing this command, nmcli starts a session where it actively listens for secret requests. You may not see explicit output like traditional commands, but it runs in a state ready to handle secret disclosures upon NetworkManager’s request.

Use case 2: Register nmcli as a polkit agent and listen for authorization requests

Code:

nmcli agent polkit

Motivation:

In network environments where authorization and privileges are a concern, running nmcli as a polkit agent can be particularly advantageous. This setup allows nmcli to handle authorization requests, granting or denying permission for certain actions based on policy configurations. It’s especially useful in multi-user systems or secure environments where actions must be explicitly authorized by administratively set policies, therefore ensuring compliance and reducing security vulnerabilities.

Explanation:

• nmcli: As before, this initiates the use of NetworkManager’s command-line tool.
• agent: Acts as the intermediary or handler between NetworkManager and requests requiring authorization.
• polkit: This argument registers the nmcli as a polkit agent, empowering it to manage authorization requests automatically according to policies set by the system administrator.

Example Output:

On running this command, the output isn’t visible like a typical shell command; however, nmcli is poised to engage in handling polkit authorization requests. It operates in the background to either grant or deny permissions based on pre-defined policy rules.

Use case 3: Register nmcli as a secret agent and a polkit agent

Code:

nmcli agent all

Motivation:

Sometimes, it may be necessary to manage both secrets and authorization requests on the same system. Using nmcli agent all allows an administrator to efficiently handle both types of requests in a consolidated manner. This dual capability minimizes the operational overhead, ensures a high level of security by combining secret and policy management, and simplifies the monitoring and controlling processes across various network operations.

Explanation:

• nmcli: Initiates the use of NetworkManager’s command-line functionality, facilitating direct communication with network settings.
• agent: Enables nmcli to perform agent-specific duties across secret and authorization domains.
• all: This argument is powerful as it enables nmcli to simultaneously act as both a secret and polkit agent, integrating the duties of credentials management and user authorization in one seamless operation.

Example Output:

Similar to prior commands, executing nmcli agent all localizes the tool into an active listening mode. While direct feedback isn’t displayed, it enhances nmcli to process both secret and polkit requests dynamically as NetworkManager demands.

Conclusion:

Utilizing nmcli as a secret and polkit agent is instrumental for administrators within Linux systems to manage networks with an elevated control level. Whether handling secret requests, authorization requests, or both, the approach enhances security, streamlines network operations, and aligns with automated systems capable of handling numerous network interactions efficiently.