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ssh2_connect

(PECL ssh2 >= 0.9.0)

ssh2_connectConexión a un servidor SSH

Descripción

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

Establece una conexión a un servidor SSH remoto.

Una vez conectado, el cliente debe verificar la clave de host del servidor utilizando la función ssh2_fingerprint(), luego identificarse utilizando un password o una clave pública.

Parámetros

host

port

methods

methods debe ser un array asociativo de hasta cuatro parámetros, como se describe a continuación. methods puede contener cualquiera o todos los parámetros siguientes.

Opciones de conexión SSH
Índice Significado Valores soportados *
kex La lista de métodos de intercambio a anunciar, separados por una coma, por orden de preferencia. diffie-hellman-group1-sha1, diffie-hellman-group14-sha1, y diffie-hellman-group-exchange-sha1
hostkey La lista de métodos de claves de host a anunciar, separados por una coma, por orden de preferencia. ssh-rsa y ssh-dss
client_to_server Array asociativo que contiene los códigos de los métodos de cifrado, compresión y mensajes de autenticación (MAC) preferidos para el envío de mensajes desde el cliente al servidor.  
server_to_client Array asociativo que contiene los códigos de los métodos de cifrado, compresión y mensajes de autenticación (MAC) preferidos para el envío de mensajes desde el servidor al cliente.  

* - Los valores soportados dependen de los métodos soportados por la biblioteca. Consulte la documentación » libssh2 para más información.

client_to_server y server_to_client deben ser un array asociativo con cualquiera o todos los parámetros siguientes.
Índice Significado Valores soportados *
crypt Lista de métodos de cifrado a anunciar, separados por una coma, por 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 métodos de compresión a anunciar, separados por una coma, por orden de preferencia. zlib y none
mac Lista de métodos MAC a anunciar, separados por una coma, por orden de preferencia. hmac-sha1, hmac-sha1-96, hmac-ripemd160, hmac-ripemd160@openssh.com, y none**

Nota: Cifrado y método MAC "none"

Por razones de seguridad, none está desactivado por la biblioteca » libssh2 a menos que se active explícitamente durante la compilación utilizando las opciones apropiadas de ./configure. Consulte la documentación de la biblioteca para más información.

callbacks

callbacks debe ser un array asociativo que contiene cualquiera o todos los parámetros siguientes.

Parámetros de retrollamada
Índice Significado Prototipo
ignore Nombre de la función a llamar cuando se recibe un paquete SSH2_MSG_IGNORE void ignore_cb($message)
debug Nombre de la función a llamar cuando se recibe un paquete SSH2_MSG_DEBUG void debug_cb($message, $language, $always_display)
macerror Nombre de la función a llamar cuando se recibe un paquete pero el código de mensaje de autenticación falla. Si la función de retrollamada devuelve true, el error será ignorado, de lo contrario, la conexión terminará. bool macerror_cb($packet)
disconnect Nombre de la función a llamar cuando se recibe un paquete SSH2_MSG_DISCONNECT void disconnect_cb($reason, $message, $language)

Valores devueltos

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

Ejemplos

Ejemplo #1 Ejemplo con ssh2_connect()

Apertura de una conexión forzando 3des-cbc al enviar paquetes, cualquier cifrado AES al recibir paquetes, ninguna compresión en ambas direcciones, y un intercambio de claves Group1.

<?php
/* Notificación al usuario si el servidor termina la conexión */
function my_ssh_disconnect($reason, $message, $language) {
printf("Servidor desconectado con código de razón [%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('Fallo en la conexión');
?>

Ver también

add a note

User Contributed Notes 8 notes

up
45
Steve Kamerman
14 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
16
thessoro at gmail dot com
10 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
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
3
jrdbrndt at gmail dot com
5 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
1
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
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
20 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
-1
rainerkrauss at googlemail dot com
11 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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