ssh2_connect

(PECL ssh2 >= 0.9.0)

ssh2_connect — Conecta a un servidor SSH

Descripción

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

Establece una conexión a un servidor SSH remoto.

Una vez conectado, el cliente debería verificar la clave de host del servidor usando ssh2_fingerprint(), y entonces, autenticarse usando la contreseña o la clave pública.

Parámetros

host

port

methods

methods puede ser un array asociativo con, hasta 4 parámetros descritos aquí abajo.

**`methods` puede ser un array asociativo con todos o alguno de los siguientes parámetros.**
Índice	Significado	Valores aceptados*
kex	Lista de métodos de intercambio de claves a revelar, separados por comas en orden de preferencia.	`diffie-hellman-group1-sha1`, `diffie-hellman-group14-sha1`, y `diffie-hellman-group-exchange-sha1`
hostkey	Lista de métodos clave-host a desvelar, separados por comas en orden de preferencia.	`ssh-rsa` y `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	Array asociativo que contiene el cifrado, la compresión, y las preferencias del método de código de autenticación de mensajes (MAC) para mensajes enviados del servidor al cliente.

* - Los valores soportados dependen de los métodos soportados por la librería subyacente. Mirar la documentación » libssh2 para obtener información adicional.

**`client_to_server` y `server_to_client` pueden ser un array asociativo con todos o algunos de los siguientes parámetros.**
Índice	Significado	Valores soportados*
crypt	Lista de métodos de cifrado a desvelar, separados por comas y en orden de preferencia.	`rijndael-cbc@lysator.liu.se`, `aes256-cbc`, `aes192-cbc`, `aes128-cbc`, `3des-cbc`, `blowfish-cbc`, `cast128-cbc`, `arcfour`, y `none**`
comp	Lista de los métodos de compresión a desvelar, separados por comas y en orden de preferencia.	`zlib` y `none`
mac	Lista de métodos MAC a desvelar, separados por comas y en orden de preferencia.	`hmac-sha1`, `hmac-sha1-96`, `hmac-ripemd160`, `hmac-ripemd160@openssh.com`, y `none**`

Nota: Método de encriptación y MAC "none"

Por razones de seguridad, none está deshabilitado por la librería subyacente » libssh2 a menos que esté habilitado explícitamente durante el tiempo de construcción usando la optión apropiada de ./configure. Lea la documentación de dicha librería para más información.

callbacks

callbacks puede ser un array asociativo con todos o alguno de los siguientes parámtros.

**Parámetros de devolución**
Índice	Significado	Prototipo
ignore	Nombre de la función a llamar cuando el paquete `SSH2_MSG_IGNORE` es recibido	void ignore_cb($message)
debug	Nombre de la función a llamar cuando el paquete `SSH2_MSG_DEBUG` es recibido	void debug_cb($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	Nombre de la función a llamar cuando el paquete `SSH2_MSG_DISCONNECT` es recibido	void disconnect_cb($reason, $message, $language)

Valores devueltos

Devuelve un recurso en caso de éxito, o false en caso de error.

Ejemplos

Ejemplo #1 ssh2_connect()

Abre una conexión forzando 3des-cbc cuando envía paquetes, cualquier grado de cifrado aes cuando se reciben paquetes, sin comprensión ni dirección, y Group1 como clave de cambio.

<?php
/* Notifica al usuario si el servidor ha terminado la conexión */
function my_ssh_disconnect($reason, $message, $language) {
  printf("Servidor desconectado con el siguiente código [%d] y mensaje: %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('Conexión fallida');
?>

Ver también

ssh2_fingerprint() - Retrieve fingerprint of remote server
ssh2_auth_none() - Authenticate as "none"
ssh2_auth_password() - Authenticate over SSH using a plain password
ssh2_auth_pubkey_file() - Authenticate using a public key

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User Contributed Notes 8 notes

down

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.]

down

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 ;)

down

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.

down

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);
}

?>

down

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.

down

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; 

  }

}

?>

down

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
?>

down

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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