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    ssh2_connect

    (PECL ssh2 >= 0.9.0)

    ssh2_connect — Connect to an SSH server

    Descrierea

    ssh2_connect ( string $host , int $port = 22 , array $methods = ? , array $callbacks = ? ) : resource

    Establish a connection to a remote SSH server.

    Once connected, the client should verify the server's hostkey using ssh2_fingerprint(), then authenticate using either password or public key.

    Parametri

    host

    port

    methods

    methods may be an associative array with up to four parameters as described below.

    methods may be an associative array with any or all of the following parameters.
    Index Meaning Supported Values*
    kex List of key exchange methods to advertise, comma separated in order of preference. diffie-hellman-group1-sha1, diffie-hellman-group14-sha1, and diffie-hellman-group-exchange-sha1
    hostkey List of hostkey methods to advertise, comma separated in order of preference. ssh-rsa and ssh-dss
    client_to_server Associative array containing crypt, compression, and message authentication code (MAC) method preferences for messages sent from client to server.  
    server_to_client Associative array containing crypt, compression, and message authentication code (MAC) method preferences for messages sent from server to client.  

    * - Supported Values are dependent on methods supported by underlying library. See » libssh2 documentation for additional information.

    client_to_server and server_to_client may be an associative array with any or all of the following parameters.
    Index Meaning Supported Values*
    crypt List of crypto methods to advertise, comma separated in order of preference. rijndael-cbc@lysator.liu.se, aes256-cbc, aes192-cbc, aes128-cbc, 3des-cbc, blowfish-cbc, cast128-cbc, arcfour, and none**
    comp List of compression methods to advertise, comma separated in order of preference. zlib and none
    mac List of MAC methods to advertise, comma separated in order of preference. hmac-sha1, hmac-sha1-96, hmac-ripemd160, hmac-ripemd160@openssh.com, and none**

    Notă: Crypt and MAC method "none"

    For security reasons, none is disabled by the underlying » libssh2 library unless explicitly enabled during build time by using the appropriate ./configure options. See documentation for the underlying library for more information.

    callbacks

    callbacks may be an associative array with any or all of the following parameters.

    Callbacks parameters
    Index Meaning Prototype
    ignore Name of function to call when an SSH2_MSG_IGNORE packet is received void ignore_cb($message)
    debug Name of function to call when an SSH2_MSG_DEBUG packet is received void debug_cb($message, $language, $always_display)
    macerror Name of function to call when a packet is received but the message authentication code failed. If the callback returns true, the mismatch will be ignored, otherwise the connection will be terminated. bool macerror_cb($packet)
    disconnect Name of function to call when an SSH2_MSG_DISCONNECT packet is received void disconnect_cb($reason, $message, $language)

    Valorile întoarse

    Returns a resource on success, or false on error.

    Exemple

    Example #1 ssh2_connect() example

    Open a connection forcing 3des-cbc when sending packets, any strength aes cipher when receiving packets, no compression in either direction, and Group1 key exchange.

    <?php
    /* Notify the user if the server terminates the connection */
    function my_ssh_disconnect($reason, $message, $language) {
          printf("Server disconnected with reason code [%d] and message: %s\n",
                 $reason, $message);
    }

    $methods = array(
          'kex' => 'diffie-hellman-group1-sha1',
          'client_to_server' => array(
            'crypt' => '3des-cbc',
            'comp' => 'none'),
          'server_to_client' => array(
            'crypt' => 'aes256-cbc,aes192-cbc,aes128-cbc',
            'comp' => 'none'));

    $callbacks = array('disconnect' => 'my_ssh_disconnect');

    $connection = ssh2_connect('shell.example.com', 22, $methods, $callbacks);
    if (!    $connection) die('Connection failed');
    ?>

    A se vedea și

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    User Contributed Notes 8 notes

    up
    43
    Steve Kamerman
    13 years ago
    Due to a lack of complete examples, here's a simple SSH2 class for connecting to a server, authenticating with public key authentication, verifying the server's fingerprint, issuing commands and reading their STDOUT and properly disconnecting.  Note: You may need to make sure you commands produce output so the response can be pulled.  Some people suggest that the command is not executed until you pull the response back.
    <?php
    class NiceSSH {
            // SSH Host
            private $ssh_host = 'myserver.example.com';
            // SSH Port
            private $ssh_port = 22;
            // SSH Server Fingerprint
            private $ssh_server_fp = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx';
            // SSH Username
            private $ssh_auth_user = 'username';
            // SSH Public Key File
            private $ssh_auth_pub = '/home/username/.ssh/id_rsa.pub';
            // SSH Private Key File
            private $ssh_auth_priv = '/home/username/.ssh/id_rsa';
            // SSH Private Key Passphrase (null == no passphrase)
            private $ssh_auth_pass;
            // SSH Connection
            private $connection;
       
        public function     connect() {
            if (!(    $this->connection = ssh2_connect($this->ssh_host, $this->ssh_port))) {
                throw new     Exception('Cannot connect to server');
            }
                $fingerprint = ssh2_fingerprint($this->connection, SSH2_FINGERPRINT_MD5 | SSH2_FINGERPRINT_HEX);
            if (    strcmp($this->ssh_server_fp, $fingerprint) !== 0) {
                throw new     Exception('Unable to verify server identity!');
            }
            if (!    ssh2_auth_pubkey_file($this->connection, $this->ssh_auth_user, $this->ssh_auth_pub, $this->ssh_auth_priv, $this->ssh_auth_pass)) {
                throw new     Exception('Autentication rejected by server');
            }
        }
        public function     exec($cmd) {
            if (!(    $stream = ssh2_exec($this->connection, $cmd))) {
                throw new     Exception('SSH command failed');
            }
                stream_set_blocking($stream, true);
                $data = "";
            while (    $buf = fread($stream, 4096)) {
                    $data .= $buf;
            }
                fclose($stream);
            return     $data;
        }
        public function     disconnect() {
                $this->exec('echo "EXITING" && exit;');
                $this->connection = null;
        }
        public function     __destruct() {
                $this->disconnect();
        }
    }
    ?>

    [EDIT BY danbrown AT php DOT net: Contains two bugfixes suggested by 'AlainC' in user note #109185 (removed) on 26-JUN-2012.]
    up
    18
    thessoro at gmail dot com
    9 years ago
    Be careful when providing a specific hostkey order.

    <?php
    ssh2_connect    ('IP', 'port', array('hostkey'=>'ssh-rsa, ssh-dss'));
    ?>

    Will only work when the public key of the server is RSA, and not DSA also as expected. This is caused by the empty space before the "ssh-dss".

    So a similar code:

    <?php
    ssh2_connect    ('IP', 'port',   array('hostkey'=>'ssh-rsa,ssh-dss'));
    ?>

    Will work. The HOSTKEY method is overriden using exactly what you write, so no empty spaces are allowed.

    This took me some time that you could save ;)
    up
    3
    jrdbrndt at gmail dot com
    4 years ago
    Trying to include "aes256-cbc" in the encryption methods list caused an error. The documentation here may be out of date, and you might find a more accurate list of what values are acceptable by checking the libssh2 documentation at libssh2.org.
    up
    11
    christophermjgray at gmail dot com
    7 years ago
    This page is out of date.  Any of the SHA-1 in the Key Exchange Methods in the kex section should be discarded, due to Logjam (https://weakdh.org/logjam.html).  If you continue to use them, connects will result in the following warning:
    "Warning: ssh2_connect(): Error starting up SSH connection(-5): Unable to exchange encryption keys in ..."

    The following is an example of what works.  Also by removing the 'hex' section all together, results in libssl (https://libssh2.org/) falling back to discovering which is the strongest cipher to authenticate with.

    <?php

    if (!function_exists("ssh2_connect")) die("function ssh2_connect doesn't exist");

    function     ssh2_debug($message, $language, $always_display) {
           printf("%s %s %s\n",$message,$language,$always_display);
    }

    /* Notify the user if the server terminates the connection */
    function my_ssh_disconnect($reason, $message, $language) {
          printf("Server disconnected with reason code [%d] and message: %s\n", $reason, $message);
    }

    $methods = array(
            'hostkey'=>'ssh-rsa,ssh-dss',
    //    'kex' => 'diffie-hellman-group-exchange-sha256',
            'client_to_server' => array(
                'crypt' => 'aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc,3des-cbc,blowfish-cbc',
                'comp' => 'none'),
            'server_to_client' => array(
                'crypt' => 'aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc,3des-cbc,blowfish-cbc',
                'comp' => 'none'));
           
    $callbacks = array('disconnect' => 'my_ssh_disconnect');

    foreach (array(    '192.168.1.1') as $host) {
          $connection = ssh2_connect($host, 22, $methods, $callbacks);
      if (!    $connection) die("Connection failed:");

          ssh2_auth_password($connection, 'user', 'my_password') or die("Unable to authenticate");
          $stream = ssh2_exec($connection, 'free -m');
          stream_set_blocking($stream, true);
          $stream_out = ssh2_fetch_stream($stream, SSH2_STREAM_STDIO);
      echo     stream_get_contents($stream_out);
    }

    ?>
    up
    1
    Trev White
    11 years ago
    Hi,
    If you are having problems with running a ssh2 session and it waits forever during the execution of stream_get_contents, it might be because the remote system has run the command and is now sitting at a # prompt waiting for the next command.  I had this issue on a HP MSA box, here is the code to get around the issue.

    Assuming you are connected with your authentication method and $ssh contains the handle.

    <?php
    $command     = "check disk";
    // Open a nice large window to stop wrapping
    $stream = ssh2_shell ($ssh, 'xterm', null, 200, 200, SSH2_TERM_UNIT_CHARS);

    // Hook into the error stream
    $errorStream = ssh2_fetch_stream($stream, SSH2_STREAM_STDERR); 

    // Block the streams so we wait until they complete
    stream_set_blocking ($stream, true);
    stream_set_blocking($errorStream, true);

    // Send the commands to the terminal
    fwrite ($stream, $command . PHP_EOL );

    // Wait give the terminal a chance to accept and start processing the command, this is a slow storage device after all
    sleep(2);

    // IMPORTANT BIT!!  Send exit to the terminal to close the connection BEFORE WE WAIT FOR THE STREAM
    fwrite ($stream, "exit" . PHP_EOL );
    sleep (2);

    // Print the output
    echo stream_get_contents($stream);
    $errortext=stream_get_contents($errorStream);

    if (    strlen($errortext) > 0) {
                  // Error Data
                 echo "Error Data: $errortext";
             exit (    1);
    }

    // All Good
    exit (0);

    ?>

    You can't use ssh2_exec with this method (well at lease I couldn't) because on executing the first command the stream gets blocked and then you can't run the exit command, whereas a terminal seems to use one session.

    I hope this helps someone.
    up
    1
    suri dot suribala dot com
    19 years ago
    With Sara's help, I have the following SS2 class that is quite flexible. If anyone improves it, please feel free to let me know.

    <?php

    // ssh protocols
    // note: once openShell method is used, cmdExec does not work

    class ssh2 {

      private     $host = 'host';
      private     $user = 'user';
      private     $port = '22';
      private     $password = 'password';
      private     $con = null;
      private     $shell_type = 'xterm';
      private     $shell = null;
      private     $log = '';

      function     __construct($host='', $port=''  ) {

         if(     $host!='' ) $this->host  = $host;
         if(     $port!='' ) $this->port  = $port;

             $this->con  = ssh2_connect($this->host, $this->port);
         if( !    $this->con ) {
               $this->log .= "Connection failed !";
         }

      }

      function     authPassword( $user = '', $password = '' ) {

         if(     $user!='' ) $this->user  = $user;
         if(     $password!='' ) $this->password  = $password;

         if( !    ssh2_auth_password( $this->con, $this->user, $this->password ) ) {
               $this->log .= "Authorization failed !";
         }

      }

      function     openShell( $shell_type = '' ) {

            if (     $shell_type != '' ) $this->shell_type = $shell_type;
            $this->shell = ssh2_shell( $this->con,  $this->shell_type );
        if( !    $this->shell ) $this->log .= " Shell connection failed !";

      }

      function     writeShell( $command = '' ) {

            fwrite($this->shell, $command."\n");

      }

      function     cmdExec( ) {

                $argc = func_num_args();
                $argv = func_get_args();

            $cmd = '';
        for(     $i=0; $i<$argc ; $i++) {
            if(     $i != ($argc-1) ) {
                  $cmd .= $argv[$i]." && ";
            }else{
                  $cmd .= $argv[$i];
            }
        }
        echo     $cmd;

                $stream = ssh2_exec( $this->con, $cmd );
            stream_set_blocking( $stream, true );
        return     fread( $stream, 4096 );

      }

      function     getLog() {

         return     $this->log;

      }

    }

    ?>
    up
    0
    devoldemar
    1 year ago
    Usage of 'hostkey' option makes sence when you need to check authenticity of the remote server, e.g. by means of ssh2_fingerprint function. For that purpose you specify a list of possible algorithms sorted by priority in descending order. Supported values also include 'ssh-ed25519', 'ecdsa-sha2-nistp256', 'ecdsa-sha2-nistp384' and 'ecdsa-sha2-nistp521'.
    For instance:
    <?php
    $ssh     = ssh2_connect('192.168.3.1', 22, ['hostkey' => 'ssh-ed25519,ssh-rsa']);
    $md5 = ssh2_fingerprint($ssh); // returns MD5 hash of ED25519 host key, or MD5 hash of RSA key if the key of previous type is absent
    ?>

    Note, if the remote server does not have a key of appropriate type connection will fail:
    <?php
    $ssh     = ssh2_connect('192.168.3.1', 22, ['hostkey' => 'ssh-dss']);
    PHP Warning:  ssh2_connect(): Error starting up SSH connection(-5): Unable to exchange encryption keys in php shell code on line 1
    PHP Warning    :  ssh2_connect(): Unable to connect to 192.168.3.1 in php shell code on line 1
    ?>
    up
    0
    rainerkrauss at googlemail dot com
    10 years ago
    Warning! If you open a ssh connection and execute an external program opening another ssh connection it may result in very strange behavior.

    I used an sftp connection to get a file list and used "exec" to download the files afterwards with an external sftp. lftp downloaded zeros with no comment, psftp exits with error code 11 most of the time, but sometimes it works - probably depending on how quickly php collects garbage and closes the unused connection first.

    As there is no function to close a connection, you need to be sure to destroy all references (unset) to close it.
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