Nessus MCP Server

Instructions

Implementation Reference

• src/tools/scans.ts:79-111 (handler)

  Main handler function for the 'start_scan' MCP tool. Validates input (target and scan_type), calls the underlying startScan API function, formats the response as MCP content, and handles errors.

  export const startScanToolHandler = async (args: Record<string, unknown>) => {
    try {
      // Validate arguments
      const targetSchema = z.string().min(1);
      const scanTypeSchema = z.enum(['basic-network-scan', 'web-app-scan', 'compliance-scan']);
  
      const target = validateTarget(args.target);
      const scanType = validateScanType(args.scan_type);
  
      // Start the scan
      const result = await startScan(target, scanType);
  
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify(result, null, 2)
          }
        ]
      };
    } catch (error) {
      const mcpError = handleNessusApiError(error);
      return {
        content: [
          {
            type: 'text',
            text: `Error: ${mcpError.message}`
          }
        ],
        isError: true
      };
    }
  };

• src/tools/scans.ts:60-77 (schema)

  Schema definition for the 'start_scan' tool, specifying name, description, and input schema with required target and scan_type parameters.

  export const startScanToolSchema = {
    name: 'start_scan',
    description: 'Start a new vulnerability scan against a target',
    inputSchema: {
      type: 'object',
      properties: {
        target: {
          type: 'string',
          description: 'Target IP address or hostname to scan'
        },
        scan_type: {
          type: 'string',
          description: 'Type of scan to run (basic-network-scan, web-app-scan, compliance-scan)'
        }
      },
      required: ['target', 'scan_type']
    }
  };

• src/index.ts:99-100 (registration)

  Registration/dispatch of the 'start_scan' tool handler in the main tool call switch statement.

  case 'start_scan':
    return await startScanToolHandler(args);

• src/index.ts:75-83 (registration)

  Registration of the 'start_scan' tool schema in the list of available tools returned by ListToolsRequest.

  tools: [
    listScanTemplatesToolSchema,
    startScanToolSchema,
    getScanStatusToolSchema,
    getScanResultsToolSchema,
    listScansToolSchema,
    getVulnerabilityDetailsToolSchema,
    searchVulnerabilitiesToolSchema
  ]

• src/nessus-api.ts:67-79 (helper)

  Underlying helper function called by the handler to start the scan. Currently implements mock mode creating a mock scan ID and queuing status.

  export const startScan = async (target: string, scanType: string) => {
    if (config.useMock) {
      const scanId = createMockScan(target, scanType);
      return {
        scan_id: scanId,
        status: "queued",
        message: "Scan queued successfully"
      };
    }
  
    // Real API implementation would go here
    throw new Error("Real API not implemented");
  };