/**
 * Create a TCP socket with SO_REUSEADDR and SO_REUSEPORT enabled.
 *
 * Use the returned fd to create a [net.Server](https://nodejs.org/docs/latest-v16.x/api/net.html#class-netserver):
 *
 * ```typescript
 * const fd = createReuseportFd(9229, '127.0.0.0');
 * const server = require('net').createServer();
 * server.listen({ fd }, () => { console.log('listen() successfully') })
 * ```
 *
 * @param port
 * @param host
 * @returns Return a fd binds to the address.
 */
export declare function createReuseportFd(port?: number, host?: string): number;
/**
 * Close a fd.
 *
 * Note that you don't need to manually close fd that is listened by net.Server.
 * @param fd
 */
export declare function closeFd(fd: number): void;