Google SecOps MCP with MCP Proxy Authentication approach

You can but its complicated.   It would be easier to use OAUTH. 

Step 1: Configure Workforce Identity Federation (WIF)

Your users must be able to generate local federated tokens using their Entra ID credentials.

1. In the Google Cloud Console (Organization level), ensure you have a Workforce Identity Pool configured for Microsoft Entra ID.

2. Map your Entra ID user attributes (e.g., user.userprincipalname mapped to google.subject).

3. Ensure the mapped users/groups are assigned the following IAM roles in your SecOps Google Cloud project:

   • roles/mcp.toolUser (To invoke MCP tool calls).

   • roles/chronicle.admin or tailored read permissions (To allow the MCP tools to query your SecOps data).

Step 2: Configure the Local User Environment

To initiate the token generation through your central proxy, your security analysts must configure their terminal/gcloud environment to route traffic through your exit point.

On the analyst's workstation, set the proxy environment variables before authenticating:

Bash

# Set your central exit proxy
export HTTP_PROXY="http://your-mcp-proxy-server.internal:8080"
export HTTPS_PROXY="http://your-mcp-proxy-server.internal:8080"

# Authenticate to Google Cloud using the federated identity
gcloud auth login --login-config=YOUR_WIF_CONFIG_FILE.json

Once authenticated, the local gcloud configuration or target application will generate short-lived OAuth 2.0 access tokens matching the federated identity.

Step 3: Configure the Central MCP Proxy Server

Your proxy server must act as a forward proxy or a reverse proxy capable of handling HTTPS tunneling (CONNECT method) or passing authorization headers transparently.

Because Google Cloud endpoints require TLS termination at Google's edge, a Forward Proxy using TLS Tunneling (HTTPS CONNECT) is typically the easiest to maintain:

• Transparent Header Passing: Ensure your proxy does not strip or alter the Authorization header. The Bearer <token> contains the federated user's identity.

• Allowed Destinations: Whitelist the specific Google Cloud Remote MCP API endpoints. For SecOps, these are region-specific:

  • [https://chronicle.googleapis.com/mcp](https://chronicle.googleapis.com/mcp)

  • Regional endpoints (e.g., [https://chronicle.us.rep.googleapis.com/mcp](https://chronicle.us.rep.googleapis.com/mcp) or [https://chronicle.europe-west3.rep.googleapis.com/mcp](https://chronicle.europe-west3.rep.googleapis.com/mcp))

If you are using a standard Squid proxy, your configuration whitelist block would look like this:

acl google_mcp dstdomain .googleapis.com
http_access allow google_mcp

Step 4: Connecting the MCP Client via the Proxy

When configuring the host application's local config file (e.g., claude_desktop_config.json or your specific internal IDE plugin settings), you point the client to your regional SecOps MCP endpoint, relying on the environment variables defined in Step 2 to force the proxy routing.

An example config configuration using the gcloud wrapper to pass the token dynamically:

JSON

{
  "mcpServers": {
    "google-secops-remote": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-google-secops", 
        "--endpoint", "https://chronicle.us.rep.googleapis.com/mcp"
      ],
      "env": {
        "HTTP_PROXY": "http://your-mcp-proxy-server.internal:8080",
        "HTTPS_PROXY": "http://your-mcp-proxy-server.internal:8080"
      }
    }
  }
}

Critical Considerations

⚠️ TLS Inspection Warning: If your corporate MCP Proxy Server performs deep packet inspection (SSL/TLS Decryption), it will break the connection unless your local client workstations explicitly trust your proxy's internal Root Certificate Authority (CA) certificate.

👤 Audit Logs Integrity: Because you are using Workforce Identity Federation, Cloud Audit Logs will accurately log the specific user's Entra ID principal name executing the search commands, even though all requests originate over the wire from the single, central Proxy Server IP address.