/**
 * MultiProtocolProxyChain.js
 *
 * Node.js class that implements a local proxy server (http/https/socks4/socks5/ssh)
 * whose outgoing connections are strictly chained through a user-provided list
 * of upstream proxies in the given order:
 *
 *   client -> local proxy -> proxies[0] -> proxies[1] -> ... -> target
 *
 * Upstream proxy object format (example):
 * {
 *   protocol: 'socks5' | 'socks4' | 'http' | 'https' | 'ssh',
 *   host: '1.2.3.4',
 *   port: 1080,
 *   userId: 'user',          // optional for auth
 *   password: 'pass'         // optional
 * }
 *
 * Dependencies: ssh2
 *  npm i ssh2
 *
 * NOTE: This implementation focuses on correctness of chaining and
 *       protocol handshakes; it is not production-hardened for all
 *       edge-cases (e.g. full HTTP header rewriting, TLS certificate generation).
 */
import { EventEmitter } from 'events';
type ProxySpec = {
    protocol: 'socks5' | 'socks4' | 'http' | 'https' | 'ssh';
    host: string;
    port: number;
    userId?: string;
    password?: string;
};
/**
 * MultiProtocolProxyChain class
 */
export declare class MultiProtocolProxyChain extends EventEmitter {
    private proxies;
    private servers;
    private logger;
    constructor(opts?: {
        logger?: {
            log: (...args: any[]) => void;
            error: (...args: any[]) => void;
        };
    });
    /**
     * Set upstream proxies array (in order).
     * @param {Array} proxies
     */
    setProxies(proxies: ProxySpec[]): void;
    /**
     * Start a local proxy server of given protocol on given port.
     * protocol: 'http' | 'https' | 'socks5' | 'socks4' | 'ssh' (local 'ssh' server is a raw TCP passthrough)
     * returns URL string for local proxy (eg 'socks5://127.0.0.1:2000')
     */
    start(protocol: ProxySpec['protocol'], port: number, host?: string): Promise<string>;
    /**
     * Stop all started servers
     */
    stopAll(): Promise<void>;
}
export {};
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