# clue/reactphp-socks [![Build Status](https://travis-ci.org/clue/reactphp-socks.svg?branch=master)](https://travis-ci.org/clue/reactphp-socks) Async SOCKS proxy connector client and server implementation, tunnel any TCP/IP-based protocol through a SOCKS5 or SOCKS4(a) proxy server, built on top of [ReactPHP](https://reactphp.org). The SOCKS proxy protocol family (SOCKS5, SOCKS4 and SOCKS4a) is commonly used to tunnel HTTP(S) traffic through an intermediary ("proxy"), to conceal the origin address (anonymity) or to circumvent address blocking (geoblocking). While many (public) SOCKS proxy servers often limit this to HTTP(S) port `80` and `443` only, this can technically be used to tunnel any TCP/IP-based protocol (HTTP, SMTP, IMAP etc.). This library provides a simple API to create these tunneled connections for you. Because it implements ReactPHP's standard [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface), it can simply be used in place of a normal connector. This makes it fairly simple to add SOCKS proxy support to pretty much any existing higher-level protocol implementation. Besides the client side, it also provides a simple SOCKS server implementation which allows you to build your own SOCKS proxy servers with custom business logic. * **Async execution of connections** - Send any number of SOCKS requests in parallel and process their responses as soon as results come in. The Promise-based design provides a *sane* interface to working with out of bound responses and possible connection errors. * **Standard interfaces** - Allows easy integration with existing higher-level components by implementing ReactPHP's standard [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface). * **Lightweight, SOLID design** - Provides a thin abstraction that is [*just good enough*](https://en.wikipedia.org/wiki/Principle_of_good_enough) and does not get in your way. Builds on top of well-tested components and well-established concepts instead of reinventing the wheel. * **Good test coverage** - Comes with an automated tests suite and is regularly tested against actual proxy servers in the wild. **Table of contents** * [Quickstart example](#quickstart-example) * [Usage](#usage) * [Client](#client) * [Plain TCP connections](#plain-tcp-connections) * [Secure TLS connections](#secure-tls-connections) * [HTTP requests](#http-requests) * [Protocol version](#protocol-version) * [DNS resolution](#dns-resolution) * [Authentication](#authentication) * [Proxy chaining](#proxy-chaining) * [Connection timeout](#connection-timeout) * [SOCKS over TLS](#socks-over-tls) * [Unix domain sockets](#unix-domain-sockets) * [Server](#server) * [Server connector](#server-connector) * [Authentication](#server-authentication) * [Proxy chaining](#server-proxy-chaining) * [SOCKS over TLS](#server-socks-over-tls) * [Unix domain sockets](#server-unix-domain-sockets) * [Servers](#servers) * [Using a PHP SOCKS server](#using-a-php-socks-server) * [Using SSH as a SOCKS server](#using-ssh-as-a-socks-server) * [Using the Tor (anonymity network) to tunnel SOCKS connections](#using-the-tor-anonymity-network-to-tunnel-socks-connections) * [Install](#install) * [Tests](#tests) * [License](#license) * [More](#more) ## Quickstart example Once [installed](#install), you can use the following code to create a connection to google.com via a local SOCKS proxy server: ```php $loop = React\EventLoop\Factory::create(); $connector = new React\Socket\Connector($loop); $client = new Clue\React\Socks\Client('127.0.0.1:1080', $connector); $client->connect('tcp://www.google.com:80')->then(function (ConnectionInterface $stream) { $stream->write("GET / HTTP/1.0\r\n\r\n"); }); $loop->run(); ``` If you're not already running any other [SOCKS proxy server](#servers), you can use the following code to create a SOCKS proxy server listening for connections on `localhost:1080`: ```php $loop = React\EventLoop\Factory::create(); // start a new SOCKS proxy server $server = new Clue\React\Socks\Server($loop); // listen on localhost:1080 $socket = new React\Socket\Server('127.0.0.1:1080', $loop); $server->listen($socket); $loop->run(); ``` See also the [examples](examples). ## Usage ### Client The `Client` is responsible for communication with your SOCKS server instance. Its constructor simply accepts an SOCKS proxy URI and a connector used to connect to the SOCKS proxy server address. In its most simple form, you can simply pass ReactPHP's [`Connector`](https://github.com/reactphp/socket#connector) like this: ```php $connector = new React\Socket\Connector($loop); $client = new Client('127.0.0.1:1080', $connector); ``` You can omit the port if you're using the default SOCKS port 1080: ```php $client = new Client('127.0.0.1', $connector); ``` If you need custom connector settings (DNS resolution, TLS parameters, timeouts, proxy servers etc.), you can explicitly pass a custom instance of the [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface): ```php $connector = new React\Socket\Connector($loop, array( 'dns' => '127.0.0.1', 'tcp' => array( 'bindto' => '192.168.10.1:0' ) )); $client = new Client('my-socks-server.local:1080', $connector); ``` This is one of the two main classes in this package. Because it implements ReactPHP's standard [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface), it can simply be used in place of a normal connector. Accordingly, it provides only a single public method, the [`connect()`](https://github.com/reactphp/socket#connect) method. The `connect(string $uri): PromiseInterface` method can be used to establish a streaming connection. It returns a [Promise](https://github.com/reactphp/promise) which either fulfills with a [ConnectionInterface](https://github.com/reactphp/socket#connectioninterface) on success or rejects with an `Exception` on error. This makes it fairly simple to add SOCKS proxy support to pretty much any higher-level component: ```diff - $client = new SomeClient($connector); + $proxy = new Client('127.0.0.1:1080', $connector); + $client = new SomeClient($proxy); ``` #### Plain TCP connections SOCKS proxies are most frequently used to issue HTTP(S) requests to your destination. However, this is actually performed on a higher protocol layer and this connector is actually inherently a general-purpose plain TCP/IP connector. As documented above, you can simply invoke its `connect()` method to establish a streaming plain TCP/IP connection and use any higher level protocol like so: ```php $client->connect('tcp://www.google.com:80')->then(function (ConnectonInterface $stream) { echo 'connected to www.google.com:80'; $stream->write("GET / HTTP/1.0\r\n\r\n"); // ... }); ``` You can either use the `Client` directly or you may want to wrap this connector in ReactPHP's [`Connector`](https://github.com/reactphp/socket#connector): ```php $connector = new React\Socket\Connector($loop, array( 'tcp' => $client, 'dns' => false )); $connector->connect('tcp://www.google.com:80')->then(function (ConnectonInterface $stream) { echo 'connected to www.google.com:80'; $stream->write("GET / HTTP/1.0\r\n\r\n"); // ... }); ``` See also the [first example](examples). The `tcp://` scheme can also be omitted. Passing any other scheme will reject the promise. Pending connection attempts can be cancelled by cancelling its pending promise like so: ```php $promise = $connector->connect($uri); $promise->cancel(); ``` Calling `cancel()` on a pending promise will cancel the underlying TCP/IP connection to the SOCKS server and/or the SOCKS protocol negotiation and reject the resulting promise. #### Secure TLS connections This class can also be used if you want to establish a secure TLS connection (formerly known as SSL) between you and your destination, such as when using secure HTTPS to your destination site. You can simply wrap this connector in ReactPHP's [`Connector`](https://github.com/reactphp/socket#connector) or the low-level [`SecureConnector`](https://github.com/reactphp/socket#secureconnector): ```php $connector = new React\Socket\Connector($loop, array( 'tcp' => $client, 'dns' => false )); // now create an SSL encrypted connection (notice the $ssl instead of $tcp) $connector->connect('tls://www.google.com:443')->then(function (ConnectionInterface $stream) { // proceed with just the plain text data // everything is encrypted/decrypted automatically echo 'connected to SSL encrypted www.google.com'; $stream->write("GET / HTTP/1.0\r\n\r\n"); // ... }); ``` See also the [second example](examples). If you use the low-level `SecureConnector`, then the `tls://` scheme can also be omitted. Passing any other scheme will reject the promise. Pending connection attempts can be cancelled by canceling its pending promise as usual. > Note how secure TLS connections are in fact entirely handled outside of this SOCKS client implementation. You can optionally pass additional [SSL context options](http://php.net/manual/en/context.ssl.php) to the constructor like this: ```php $connector = new React\Socket\Connector($loop, array( 'tcp' => $client, 'tls' => array( 'verify_peer' => false, 'verify_peer_name' => false ), 'dns' => false )); ``` #### HTTP requests HTTP operates on a higher layer than this low-level SOCKS implementation. If you want to issue HTTP requests, you can add a dependency for [clue/reactphp-buzz](https://github.com/clue/reactphp-buzz). It can interact with this library by issuing all [HTTP requests through a SOCKS proxy server](https://github.com/clue/reactphp-buzz#socks-proxy). This works for both plain HTTP and TLS-encrypted HTTPS requests. #### Protocol version This library supports the SOCKS5 and SOCKS4(a) protocol versions. It focuses on the most commonly used core feature of connecting to a destination host through the SOCKS proxy server. In this mode, a SOCKS proxy server acts as a generic proxy allowing higher level application protocols to work through it.
SOCKS5 SOCKS4(a)
Protocol specification RFC 1928 SOCKS4.protocol / SOCKS4A.protocol
Tunnel outgoing TCP/IP connections ✓ ✓
Remote DNS resolution ✓ ✗ / ✓
IPv6 addresses ✓ ✗
Username/Password authentication ✓ (as per RFC 1929) ✗
Handshake # roundtrips 2 (3 with authentication) 1
Handshake traffic
+ remote DNS		 variable (+ auth + IPv6)
+ hostname - 3		 17 bytes
+ hostname + 1
Incoming BIND requests not implemented not implemented
UDP datagrams not implemented ✗
GSSAPI authentication not implemented ✗
By default, the `Client` communicates via SOCKS5 with the SOCKS server. This is done because SOCKS5 is the latest version from the SOCKS protocol family and generally has best support across other vendors. You can also omit the default `socks://` URI scheme. Similarly, the `socks5://` URI scheme acts as an alias for the default `socks://` URI scheme. ```php // all three forms are equivalent $client = new Client('127.0.0.1', $connector); $client = new Client('socks://127.0.0.1', $connector); $client = new Client('socks5://127.0.0.1', $connector); ``` If want to explicitly set the protocol version to SOCKS4(a), you can use the URI scheme `socks4://` as part of the SOCKS URI: ```php $client = new Client('socks4://127.0.0.1', $connector); ``` #### DNS resolution By default, the `Client` does not perform any DNS resolution at all and simply forwards any hostname you're trying to connect to to the SOCKS server. The remote SOCKS server is thus responsible for looking up any hostnames via DNS (this default mode is thus called *remote DNS resolution*). As seen above, this mode is supported by the SOCKS5 and SOCKS4a protocols, but not the original SOCKS4 protocol, as the protocol lacks a way to communicate hostnames. On the other hand, all SOCKS protocol versions support sending destination IP addresses to the SOCKS server. In this mode you either have to stick to using IPs only (which is ofen unfeasable) or perform any DNS lookups locally and only transmit the resolved destination IPs (this mode is thus called *local DNS resolution*). The default *remote DNS resolution* is useful if your local `Client` either can not resolve target hostnames because it has no direct access to the internet or if it should not resolve target hostnames because its outgoing DNS traffic might be intercepted (in particular when using the [Tor network](#using-the-tor-anonymity-network-to-tunnel-socks-connections)). As noted above, the `Client` defaults to using remote DNS resolution. However, wrapping the `Client` in ReactPHP's [`Connector`](https://github.com/reactphp/socket#connector) actually performs local DNS resolution unless explicitly defined otherwise. Given that remote DNS resolution is assumed to be the preferred mode, all other examples explicitly disable DNS resoltion like this: ```php $connector = new React\Socket\Connector($loop, array( 'tcp' => $client, 'dns' => false )); ``` If you want to explicitly use *local DNS resolution* (such as when explicitly using SOCKS4), you can use the following code: ```php // set up Connector which uses Google's public DNS (8.8.8.8) $connector = new React\Socket\Connector($loop, array( 'tcp' => $client, 'dns' => '8.8.8.8' )); ``` See also the [fourth example](examples). Pending connection attempts can be cancelled by cancelling its pending promise as usual. > Note how local DNS resolution is in fact entirely handled outside of this SOCKS client implementation. #### Authentication This library supports username/password authentication for SOCKS5 servers as defined in [RFC 1929](https://tools.ietf.org/html/rfc1929). On the client side, simply pass your username and password to use for authentication (see below). For each further connection the client will merely send a flag to the server indicating authentication information is available. Only if the server requests authentication during the initial handshake, the actual authentication credentials will be transmitted to the server. Note that the password is transmitted in cleartext to the SOCKS proxy server, so this methods should not be used on a network where you have to worry about eavesdropping. You can simply pass the authentication information as part of the SOCKS URI: ```php $client = new Client('username:password@127.0.0.1', $connector); ``` Note that both the username and password must be percent-encoded if they contain special characters: ```php $user = 'he:llo'; $pass = 'p@ss'; $client = new Client( rawurlencode($user) . ':' . rawurlencode($pass) . '@127.0.0.1', $connector ); ``` > The authentication details will be transmitted in cleartext to the SOCKS proxy server only if it requires username/password authentication. If the authentication details are missing or not accepted by the remote SOCKS proxy server, it is expected to reject each connection attempt with an exception error code of `SOCKET_EACCES` (13). Authentication is only supported by protocol version 5 (SOCKS5), so passing authentication to the `Client` enforces communication with protocol version 5 and complains if you have explicitly set anything else: ```php // throws InvalidArgumentException new Client('socks4://user:pass@127.0.0.1', $connector); ``` #### Proxy chaining The `Client` is responsible for creating connections to the SOCKS server which then connects to the target host. ``` Client -> SocksServer -> TargetHost ``` Sometimes it may be required to establish outgoing connections via another SOCKS server. For example, this can be useful if you want to conceal your origin address. ``` Client -> MiddlemanSocksServer -> TargetSocksServer -> TargetHost ``` The `Client` uses any instance of the `ConnectorInterface` to establish outgoing connections. In order to connect through another SOCKS server, you can simply use another SOCKS connector from another SOCKS client like this: ```php // https via the proxy chain "MiddlemanSocksServer -> TargetSocksServer -> TargetHost" // please note how the client uses TargetSocksServer (not MiddlemanSocksServer!), // which in turn then uses MiddlemanSocksServer. // this creates a TCP/IP connection to MiddlemanSocksServer, which then connects // to TargetSocksServer, which then connects to the TargetHost $middle = new Client('127.0.0.1:1080', new Connector($loop)); $target = new Client('example.com:1080', $middle); $connector = new React\Socket\Connector($loop, array( 'tcp' => $target, 'dns' => false )); $connector->connect('tls://www.google.com:443')->then(function ($stream) { // … }); ``` See also the [third example](examples). Pending connection attempts can be canceled by canceling its pending promise as usual. Proxy chaining can happen on the server side and/or the client side: * If you ask your client to chain through multiple proxies, then each proxy server does not really know anything about chaining at all. This means that this is a client-only property. * If you ask your server to chain through another proxy, then your client does not really know anything about chaining at all. This means that this is a server-only property and not part of this class. For example, you can find this in the below [`Server`](#server-proxy-chaining) class or somewhat similar when you're using the [Tor network](#using-the-tor-anonymity-network-to-tunnel-socks-connections). #### Connection timeout By default, the `Client` does not implement any timeouts for establishing remote connections. Your underlying operating system may impose limits on pending and/or idle TCP/IP connections, anywhere in a range of a few minutes to several hours. Many use cases require more control over the timeout and likely values much smaller, usually in the range of a few seconds only. You can use ReactPHP's [`Connector`](https://github.com/reactphp/socket#connector) or the low-level [`TimeoutConnector`](https://github.com/reactphp/socket#timeoutconnector) to decorate any given `ConnectorInterface` instance. It provides the same `connect()` method, but will automatically reject the underlying connection attempt if it takes too long: ```php $connector = new Connector($loop, array( 'tcp' => $client, 'dns' => false, 'timeout' => 3.0 )); $connector->connect('tcp://google.com:80')->then(function ($stream) { // connection succeeded within 3.0 seconds }); ``` See also any of the [examples](examples). Pending connection attempts can be cancelled by cancelling its pending promise as usual. > Note how connection timeout is in fact entirely handled outside of this SOCKS client implementation. #### SOCKS over TLS All [SOCKS protocol versions](#protocol-version) support forwarding TCP/IP based connections and higher level protocols. This implies that you can also use [secure TLS connections](#secure-tls-connections) to transfer sensitive data across SOCKS proxy servers. This means that no eavesdropper nor the proxy server will be able to decrypt your data. However, the initial SOCKS communication between the client and the proxy is usually via an unencrypted, plain TCP/IP connection. This means that an eavesdropper may be able to see *where* you connect to and may also be able to see your [SOCKS authentication](#authentication) details in cleartext. As an alternative, you may establish a secure TLS connection to your SOCKS proxy before starting the initial SOCKS communication. This means that no eavesdroppper will be able to see the destination address you want to connect to or your [SOCKS authentication](#authentication) details. You can use the `sockss://` URI scheme or use an explicit [SOCKS protocol version](#protocol-version) like this: ```php $client = new Client('sockss://127.0.0.1:1080', new Connector($loop)); $client = new Client('socks4s://127.0.0.1:1080', new Connector($loop)); ``` See also [example 32](examples). Similarly, you can also combine this with [authentication](#authentication) like this: ```php $client = new Client('sockss://user:pass@127.0.0.1:1080', new Connector($loop)); ``` > Note that for most use cases, [secure TLS connections](#secure-tls-connections) should be used instead. SOCKS over TLS is considered advanced usage and is used very rarely in practice. In particular, the SOCKS server has to accept secure TLS connections, see also [Server SOCKS over TLS](#server-socks-over-tls) for more details. Also, PHP does not support "double encryption" over a single connection. This means that enabling [secure TLS connections](#secure-tls-connections) over a communication channel that has been opened with SOCKS over TLS may not be supported. > Note that the SOCKS protocol does not support the notion of TLS. The above works reasonably well because TLS is only used for the connection between client and proxy server and the SOCKS protocol data is otherwise identical. This implies that this may also have only limited support for [proxy chaining](#proxy-chaining) over multiple TLS paths. #### Unix domain sockets All [SOCKS protocol versions](#protocol-version) support forwarding TCP/IP based connections and higher level protocols. In some advanced cases, it may be useful to let your SOCKS server listen on a Unix domain socket (UDS) path instead of a IP:port combination. For example, this allows you to rely on file system permissions instead of having to rely on explicit [authentication](#authentication). You can use the `socks+unix://` URI scheme or use an explicit [SOCKS protocol version](#protocol-version) like this: ```php $client = new Client('socks+unix:///tmp/proxy.sock', new Connector($loop)); $client = new Client('socks4+unix:///tmp/proxy.sock', new Connector($loop)); ``` Similarly, you can also combine this with [authentication](#authentication) like this: ```php $client = new Client('socks+unix://user:pass@/tmp/proxy.sock', new Connector($loop)); ``` > Note that Unix domain sockets (UDS) are considered advanced usage and PHP only has limited support for this. In particular, enabling [secure TLS](#secure-tls-connections) may not be supported. > Note that the SOCKS protocol does not support the notion of UDS paths. The above works reasonably well because UDS is only used for the connection between client and proxy server and the path will not actually passed over the protocol. This implies that this does also not support [proxy chaining](#proxy-chaining) over multiple UDS paths. ### Server The `Server` is responsible for accepting incoming communication from SOCKS clients and forwarding the requested connection to the target host. It supports the SOCKS5 and SOCKS4(a) protocol versions by default. It also registers everything with the main [`EventLoop`](https://github.com/reactphp/event-loop#usage) and an underlying TCP/IP socket server like this: ```php $loop = React\EventLoop\Factory::create(); $server = new Clue\React\Socks\Server($loop); // listen on localhost:$port $socket = new React\Socket\Server($port, $loop); $server->listen($socket); $loop->run(); ``` Additionally, the `Server` constructor accepts optional parameters to explicitly configure the [connector](#server-connector) to use and to require [authentication](#server-authentication). For more details, read on... #### Server connector The `Server` uses an instance of ReactPHP's [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface) to establish outgoing connections for each incoming connection request. If you need custom connector settings (DNS resolution, TLS parameters, timeouts, proxy servers etc.), you can explicitly pass a custom instance of the [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface): ```php $connector = new React\Socket\Connector($loop, array( 'dns' => '127.0.0.1', 'tcp' => array( 'bindto' => '192.168.10.1:0' ) )); $server = new Clue\React\Socks\Server($loop, $connector); ``` If you want to forward the outgoing connection through another SOCKS proxy, you may also pass a [`Client`](#client) instance as a connector, see also [server proxy chaining](#server-proxy-chaining) for more details. Internally, the `Server` uses ReactPHP's normal [`connect()`](https://github.com/reactphp/socket#connect) method, but it also passes the original client IP as the `?source={remote}` parameter. The `source` parameter contains the full remote URI, including the protocol and any authentication details, for example `socks://user:pass@1.2.3.4:5678` or `socks4://1.2.3.4:5678` for legacy SOCKS4(a). You can use this parameter for logging purposes or to restrict connection requests for certain clients by providing a custom implementation of the [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface). #### Server authentication By default, the `Server` does not require any authentication from the clients. You can enable authentication support so that clients need to pass a valid username and password before forwarding any connections. Setting authentication on the `Server` enforces each further connected client to use protocol version 5 (SOCKS5). If a client tries to use any other protocol version, does not send along authentication details or if authentication details can not be verified, the connection will be rejected. If you only want to accept static authentication details, you can simply pass an additional assoc array with your authentication details to the `Server` like this: ```php $server = new Clue\React\Socks\Server($loop, null, array( 'tom' => 'password', 'admin' => 'root' )); ``` See also [example #12](examples). If you want more control over authentication, you can pass an authenticator function that should return a `bool` value like this synchronous example: ```php $server = new Clue\React\Socks\Server($loop, null, function ($user, $pass, $remote) { // $remote is a full URI à la socks://user:pass@192.168.1.1:1234 // or sockss://user:pass@192.168.1.1:1234 for SOCKS over TLS // or may be null when remote is unknown (SOCKS over Unix Domain Sockets) // useful for logging or extracting parts, such as the remote IP $ip = parse_url($remote, PHP_URL_HOST); return ($user === 'root' && $pass === 'secret' && $ip === '127.0.0.1'); }); ``` Because your authentication mechanism might take some time to actually check the provided authentication credentials (like querying a remote database or webservice), the server also supports a [Promise](https://github.com/reactphp/promise)-based interface. While this might seem more complex at first, it actually provides a very powerful way of handling a large number of connections concurrently without ever blocking any connections. You can return a [Promise](https://github.com/reactphp/promise) from the authenticator function that will fulfill with a `bool` value like this async example: ```php $server = new Clue\React\Socks\Server($loop, null, function ($user, $pass) use ($db) { // pseudo-code: query database for given authentication details return $db->query( 'SELECT 1 FROM users WHERE name = ? AND password = ?', array($username, $password) )->then(function (QueryResult $result) { // ensure we find exactly one match in the database return count($result->resultRows) === 1; }); }); ``` #### Server proxy chaining The `Server` is responsible for creating connections to the target host. ``` Client -> SocksServer -> TargetHost ``` Sometimes it may be required to establish outgoing connections via another SOCKS server. For example, this can be useful if your target SOCKS server requires authentication, but your client does not support sending authentication information (e.g. like most webbrowser). ``` Client -> MiddlemanSocksServer -> TargetSocksServer -> TargetHost ``` The `Server` uses any instance of the `ConnectorInterface` to establish outgoing connections. In order to connect through another SOCKS server, you can simply use the [`Client`](#client) SOCKS connector from above. You can create a SOCKS `Client` instance like this: ```php $loop = React\EventLoop\Factory::create(); // set next SOCKS server example.com:1080 as target $connector = new React\Socket\Connector($loop); $client = new Clue\React\Socks\Client('user:pass@example.com:1080', $connector); // start a new server which forwards all connections to the other SOCKS server $server = new Clue\React\Socks\Server($loop, $client); // listen on localhost:1080 $socket = new React\Socket\Server('127.0.0.1:1080', $loop); $server->listen($socket); $loop->run(); ``` See also [example #21](examples). Proxy chaining can happen on the server side and/or the client side: * If you ask your client to chain through multiple proxies, then each proxy server does not really know anything about chaining at all. This means that this is a client-only property and not part of this class. For example, you can find this in the above [`Client`](#proxy-chaining) class. * If you ask your server to chain through another proxy, then your client does not really know anything about chaining at all. This means that this is a server-only property and can be implemented as above. #### Server SOCKS over TLS Both SOCKS5 and SOCKS4(a) protocol versions support forwarding TCP/IP based connections and higher level protocols. This implies that you can also use [secure TLS connections](#secure-tls-connections) to transfer sensitive data across SOCKS proxy servers. This means that no eavesdropper nor the proxy server will be able to decrypt your data. However, the initial SOCKS communication between the client and the proxy is usually via an unencrypted, plain TCP/IP connection. This means that an eavesdropper may be able to see *where* the client connects to and may also be able to see the [SOCKS authentication](#authentication) details in cleartext. As an alternative, you may listen for SOCKS over TLS connections so that the client has to establish a secure TLS connection to your SOCKS proxy before starting the initial SOCKS communication. This means that no eavesdroppper will be able to see the destination address the client wants to connect to or their [SOCKS authentication](#authentication) details. You can simply start your listening socket on the `tls://` URI scheme like this: ```php $loop = React\EventLoop\Factory::create(); $server = new Clue\React\Socks\Server($loop); // listen on tls://127.0.0.1:1080 with the given server certificate $socket = new React\Socket\Server('tls://127.0.0.1:1080', $loop, array( 'tls' => array( 'local_cert' => __DIR__ . '/localhost.pem', ) )); $server->listen($socket); $loop->run(); ``` See also [example 31](examples). > Note that for most use cases, [secure TLS connections](#secure-tls-connections) should be used instead. SOCKS over TLS is considered advanced usage and is used very rarely in practice. > Note that the SOCKS protocol does not support the notion of TLS. The above works reasonably well because TLS is only used for the connection between client and proxy server and the SOCKS protocol data is otherwise identical. This implies that this does also not support [proxy chaining](#server-proxy-chaining) over multiple TLS paths. #### Server Unix domain sockets Both SOCKS5 and SOCKS4(a) protocol versions support forwarding TCP/IP based connections and higher level protocols. In some advanced cases, it may be useful to let your SOCKS server listen on a Unix domain socket (UDS) path instead of a IP:port combination. For example, this allows you to rely on file system permissions instead of having to rely on explicit [authentication](#server-authentication). You can simply start your listening socket on the `unix://` URI scheme like this: ```php $loop = React\EventLoop\Factory::create(); $server = new Clue\React\Socks\Server($loop); // listen on /tmp/proxy.sock $socket = new React\Socket\Server('unix:///tmp/proxy.sock', $loop); $server->listen($socket); $loop->run(); ``` > Note that Unix domain sockets (UDS) are considered advanced usage and that the SOCKS protocol does not support the notion of UDS paths. The above works reasonably well because UDS is only used for the connection between client and proxy server and the path will not actually passed over the protocol. This implies that this does also not support [proxy chaining](#server-proxy-chaining) over multiple UDS paths. ## Servers ### Using a PHP SOCKS server * If you're looking for an end-user SOCKS server daemon, you may want to use [LeProxy](https://leproxy.org/) or [clue/psocksd](https://github.com/clue/psocksd). * If you're looking for a SOCKS server implementation, consider using the above [`Server`](#server) class. ### Using SSH as a SOCKS server If you already have an SSH server set up, you can easily use it as a SOCKS tunnel end point. On your client, simply start your SSH client and use the `-D ` option to start a local SOCKS server (quoting the man page: a `local "dynamic" application-level port forwarding`). You can start a local SOCKS server by creating a loopback connection to your local system if you already run an SSH daemon: ```bash $ ssh -D 1080 localhost ``` Alternatively, you can start a local SOCKS server tunneling through a given remote host that runs an SSH daemon: ```bash $ ssh -D 1080 example.com ``` Now you can simply use this SSH SOCKS server like this: ```PHP $client = new Client('127.0.0.1:1080', $connector); ``` Note that the above will allow all users on the local system to connect over your SOCKS server without authentication which may or may not be what you need. As an alternative, recent OpenSSH client versions also support [Unix domain sockets](#unix-domain-sockets) (UDS) paths so that you can rely on Unix file system permissions instead: ```bash $ ssh -D/tmp/proxy.sock example.com ``` Now you can simply use this SSH SOCKS server like this: ```PHP $client = new Client('socks+unix:///tmp/proxy.sock', $connector); ``` ### Using the Tor (anonymity network) to tunnel SOCKS connections The [Tor anonymity network](https://www.torproject.org) client software is designed to encrypt your traffic and route it over a network of several nodes to conceal its origin. It presents a SOCKS5 and SOCKS4(a) interface on TCP port 9050 by default which allows you to tunnel any traffic through the anonymity network: ```php $client = new Client('127.0.0.1:9050', $connector); ``` In most common scenarios you probably want to stick to default [remote DNS resolution](#dns-resolution) and don't want your client to resolve the target hostnames, because you would leak DNS information to anybody observing your local traffic. Also, Tor provides hidden services through an `.onion` pseudo top-level domain which have to be resolved by Tor. ## Install The recommended way to install this library is [through Composer](https://getcomposer.org). [New to Composer?](https://getcomposer.org/doc/00-intro.md) This project follows [SemVer](https://semver.org/). This will install the latest supported version: ```bash $ composer require clue/socks-react:^1.0 ``` See also the [CHANGELOG](CHANGELOG.md) for details about version upgrades. This project aims to run on any platform and thus does not require any PHP extensions and supports running on legacy PHP 5.3 through current PHP 7+ and HHVM. It's *highly recommended to use PHP 7+* for this project. ## Tests To run the test suite, you first need to clone this repo and then install all dependencies [through Composer](https://getcomposer.org): ```bash $ composer install ``` To run the test suite, go to the project root and run: ```bash $ php vendor/bin/phpunit ``` The test suite contains a number of tests that rely on a working internet connection, alternatively you can also run it like this: ```bash $ php vendor/bin/phpunit --exclude-group internet ``` ## License This project is released under the permissive [MIT license](LICENSE). > Did you know that I offer custom development services and issuing invoices for sponsorships of releases and for contributions? Contact me (@clue) for details. ## More * If you want to learn more about how the [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface) and its usual implementations look like, refer to the documentation of the underlying [react/socket component](https://github.com/reactphp/socket). * If you want to learn more about processing streams of data, refer to the documentation of the underlying [react/stream](https://github.com/reactphp/stream) component. * As an alternative to a SOCKS5 / SOCKS4(a) proxy, you may also want to look into using an HTTP CONNECT proxy instead. You may want to use [clue/reactphp-http-proxy](https://github.com/clue/reactphp-http-proxy) which also provides an implementation of the same [`ConnectorInterface`](https://github.com/reactphp/socket#connectorinterface) so that supporting either proxy protocol should be fairly trivial. * If you're dealing with public proxies, you'll likely have to work with mixed quality and unreliable proxies. You may want to look into using [clue/reactphp-connection-manager-extra](https://github.com/clue/reactphp-connection-manager-extra) which allows retrying unreliable ones, implying connection timeouts, concurrently working with multiple connectors and more. * If you're looking for an end-user SOCKS server daemon, you may want to use [LeProxy](https://leproxy.org/) or [clue/psocksd](https://github.com/clue/psocksd).