ssh2

What is ssh2?

The ssh2 npm package is a client and server module for SSH and SFTP written in pure JavaScript for node.js. It provides an interface to connect to and interact with SSH servers, allowing for the execution of commands, file transfers, local and remote port forwarding, and more.

What are ssh2's main functionalities?

Executing Commands on Remote Server

This code sample demonstrates how to execute a command (in this case, 'uptime') on a remote server using the ssh2 package.

const { Client } = require('ssh2');

const conn = new Client();
conn.on('ready', () => {
  console.log('Client :: ready');
  conn.exec('uptime', (err, stream) => {
    if (err) throw err;
    stream.on('close', (code, signal) => {
      console.log('Stream :: close :: code: ' + code + ', signal: ' + signal);
      conn.end();
    }).on('data', (data) => {
      console.log('STDOUT: ' + data);
    }).stderr.on('data', (data) => {
      console.log('STDERR: ' + data);
    });
  });
}).connect({
  host: '192.168.100.100',
  port: 22,
  username: 'frylock',
  privateKey: require('fs').readFileSync('/here/is/my/key')
});

SFTP File Transfer

This code sample shows how to transfer a file from a local path to a remote path using SFTP with the ssh2 package.

const { Client } = require('ssh2');

const conn = new Client();
conn.on('ready', () => {
  console.log('Client :: ready');
  conn.sftp((err, sftp) => {
    if (err) throw err;
    sftp.fastPut(localPath, remotePath, {}, (err) => {
      if (err) throw err;
      console.log('File transferred successfully!');
      conn.end();
    });
  });
}).connect({
  host: '192.168.100.100',
  port: 22,
  username: 'frylock',
  privateKey: require('fs').readFileSync('/here/is/my/key')
});

TCP Port Forwarding

This code sample illustrates how to set up TCP port forwarding from the local machine to a remote destination using the ssh2 package.

const { Client } = require('ssh2');

const conn = new Client();
conn.on('ready', () => {
  console.log('Client :: ready');
  conn.forwardOut('127.0.0.1', 12345, 'www.google.com', 80, (err, stream) => {
    if (err) throw err;
    stream.on('close', () => {
      console.log('TCP :: CLOSED');
      conn.end();
    }).on('data', (data) => {
      console.log('TCP :: DATA: ' + data);
    });
    stream.end('GET / HTTP/1.1\r\nHost: www.google.com\r\nConnection: close\r\n\r\n');
  });
}).connect({
  host: '192.168.100.100',
  port: 22,
  username: 'frylock',
  privateKey: require('fs').readFileSync('/here/is/my/key')
});

Other packages similar to ssh2

node-ssh

node-ssh is an SSH2 client module that provides a higher-level API for interacting with SSH servers. It simplifies tasks like executing commands and handling file transfers. Compared to ssh2, node-ssh is built on top of ssh2 and offers a more promise-based API, which can be easier to use for some developers.

simple-ssh

simple-ssh is another SSH client for node.js that aims to provide a simpler and more intuitive API than ssh2. It offers a chainable API for executing multiple commands in sequence. While it may be easier for beginners, it is not as feature-rich as ssh2 and may not be suitable for more complex SSH interactions.

README

Description

An SSH2 client module written in pure JavaScript for node.js.

Development/testing is done against OpenSSH (6.0 currently).

Requirements

• node.js -- v0.8.3 or newer

Install

npm install ssh2

Examples

• Authenticate using keys, execute uptime on a server, and disconnect afterwards:

var Connection = require('ssh2');

var c = new Connection();
c.on('connect', function() {
  console.log('Connection :: connect');
});
c.on('ready', function() {
  console.log('Connection :: ready');
  c.exec('uptime', function(err, stream) {
    if (err) throw err;
    stream.on('data', function(data, extended) {
      console.log((extended === 'stderr' ? 'STDERR: ' : 'STDOUT: ')
                  + data);
    });
    stream.on('end', function() {
      console.log('Stream :: EOF');
    });
    stream.on('close', function() {
      console.log('Stream :: close');
    });
    stream.on('exit', function(code, signal) {
      console.log('Stream :: exit :: code: ' + code + ', signal: ' + signal);
      c.end();
    });
  });
});
c.on('error', function(err) {
  console.log('Connection :: error :: ' + err);
});
c.on('end', function() {
  console.log('Connection :: end');
});
c.on('close', function(had_error) {
  console.log('Connection :: close');
});
c.connect({
  host: '192.168.100.100',
  port: 22,
  username: 'frylock',
  privateKey: require('fs').readFileSync('/here/is/my/key')
});

// example output:
// Connection :: connect
// Connection :: ready
// STDOUT:  17:41:15 up 22 days, 18:09,  1 user,  load average: 0.00, 0.01, 0.05
//
// Stream :: exit :: code: 0, signal: undefined
// Connection :: end
// Connection :: close

• Authenticate using password, send a (raw) HTTP request to port 80 on the server, and disconnect afterwards:

var Connection = require('ssh2');

var c = new Connection();
c.on('connect', function() {
  console.log('Connection :: connect');
});
c.on('ready', function() {
  console.log('Connection :: ready');
  c.forwardOut('192.168.100.102', 8000, '127.0.0.1', 80, function(err, stream) {
    if (err) throw err;
    stream.on('data', function(data) {
      console.log('TCP :: DATA: ' + data);
    });
    stream.on('end', function() {
      console.log('TCP :: EOF');
    });
    stream.on('error', function(err) {
      console.log('TCP :: ERROR: ' + err);
    });
    stream.on('close', function(had_err) {
      console.log('TCP :: CLOSED');
      c.end();
    });
    var data = [
      'HEAD / HTTP/1.1',
      'User-Agent: curl/7.27.0',
      'Host: 127.0.0.1',
      'Accept: */*',
      'Connection: close',
      '',
      ''
    ];
    stream.write(data.join('\r\n'));
  });
});
c.on('error', function(err) {
  console.log('Connection :: error :: ' + err);
});
c.on('end', function() {
  console.log('Connection :: end');
});
c.on('close', function(had_error) {
  console.log('Connection :: close');
});
c.connect({
  host: '192.168.100.100',
  port: 22,
  username: 'frylock',
  password: 'nodejsrules'
});

// example output:
// Connection :: connect
// Connection :: ready
// TCP :: DATA: HTTP/1.1 200 OK
// Date: Thu, 15 Nov 2012 13:52:58 GMT
// Server: Apache/2.2.22 (Ubuntu)
// X-Powered-By: PHP/5.4.6-1ubuntu1
// Last-Modified: Thu, 01 Jan 1970 00:00:00 GMT
// Content-Encoding: gzip
// Vary: Accept-Encoding
// Connection: close
// Content-Type: text/html; charset=UTF-8
// 
// 
// TCP :: EOF
// TCP :: CLOSED
// Connection :: end
// Connection :: close

• Authenticate using password and forward remote connections on port 8000 to us:

var Connection = require('ssh2');

var c = new Connection();
c.on('connect', function() {
  console.log('Connection :: connect');
});
c.on('tcp connection', function(info, accept, reject) {
  console.log('TCP :: INCOMING CONNECTION: ' + require('util').inspect(info));

  var stream = accept();

  stream.on('data', function(data) {
    console.log('TCP :: DATA: ' + data);
  });
  stream.on('end', function() {
    console.log('TCP :: EOF');
  });
  stream.on('error', function(err) {
    console.log('TCP :: ERROR: ' + err);
  });
  stream.on('close', function(had_err) {
    console.log('TCP :: CLOSED');
  });
  var response = [
    'HTTP/1.1 404 Not Found',
    'Date: Thu, 15 Nov 2012 02:07:58 GMT',
    'Server: ForwardedConnection',
    'Content-Length: 0',
    'Connection: close',
    '',
    ''
  ];
  stream.end(response.join('\r\n'));
});
c.on('ready', function() {
  console.log('Connection :: ready');
  c.forwardIn('127.0.0.1', 8000, function(err) {
    if (err) throw err;
    console.log('Listening for connections on server on port 8000!');
  });
});
c.on('error', function(err) {
  console.log('Connection :: error :: ' + err);
});
c.on('end', function() {
  console.log('Connection :: end');
});
c.on('close', function(had_error) {
  console.log('Connection :: close');
});
c.connect({
  host: '192.168.100.100',
  port: 22,
  username: 'frylock',
  password: 'nodejsrules'
});

// example output:
// Connection :: connect
// Connection :: ready
// Listening for connections on server on port 8000!
//  (.... then from another terminal on the server: `curl -I http://127.0.0.1:8000`)
// TCP :: INCOMING CONNECTION: { destIP: '127.0.0.1',
//  destPort: 8000,
//  srcIP: '127.0.0.1',
//  srcPort: 41969 }
// TCP DATA: HEAD / HTTP/1.1
// User-Agent: curl/7.27.0
// Host: 127.0.0.1:8000
// Accept: */*
//
//
// TCP :: CLOSED

• Authenticate using password, start an SFTP session, and get a directory listing:

var Connection = require('ssh2');

var c = new Connection();
c.on('connect', function() {
  console.log('Connection :: connect');
});
c.on('ready', function() {
  console.log('Connection :: ready');
  c.sftp(function(err, sftp) {
    if (err) throw err;
    sftp.on('end', function() {
      console.log('SFTP :: SFTP session closed');
    });
    sftp.opendir('foo', function readdir(err, handle) {
      if (err) throw err;
      sftp.readdir(handle, function(err, list) {
        if (err) throw err;
        if (list === false) {
          sftp.close(handle, function(err) {
            if (err) throw err;
            console.log('SFTP :: Handle closed');
            sftp.end();
          });
          return;
        }
        console.dir(list);
        readdir(undefined, handle);
      });
    });
  });
});
c.on('error', function(err) {
  console.log('Connection :: error :: ' + err);
});
c.on('end', function() {
  console.log('Connection :: end');
});
c.on('close', function(had_error) {
  console.log('Connection :: close');
});
c.connect({
  host: '192.168.100.100',
  port: 22,
  username: 'frylock',
  password: 'nodejsrules'
});

// example output:
// Connection :: connect
// Connection :: ready
// [ { filename: '.',
//     longname: 'drwxr-xr-x    3 mscdex   mscdex       4096 Nov 18 15:03 .',
//     attrs:
//      { size: 1048576,
//        uid: 1000,
//        gid: 1000,
//        permissions: 16877,
//        atime: 1353269008,
//        mtime: 1353269007 } },
//   { filename: '..',
//     longname: 'drwxr-xr-x   45 mscdex   mscdex       4096 Nov 18 11:03 ..',
//     attrs:
//      { size: 1048576,
//        uid: 1000,
//        gid: 1000,
//        permissions: 16877,
//        atime: 1353254582,
//        mtime: 1353254581 } },
//   { filename: 'test.txt',
//     longname: '-rw-r--r--    1 mscdex   mscdex         12 Nov 18 11:05 test.txt',
//     attrs:
//      { size: 12,
//        uid: 1000,
//        gid: 1000,
//        permissions: 33188,
//        atime: 1353254750,
//        mtime: 1353254744 } },
//   { filename: 'mydir',
//     longname: 'drwxr-xr-x    2 mscdex   mscdex       4096 Nov 18 15:03 mydir',
//     attrs:
//      { size: 1048576,
//        uid: 1000,
//        gid: 1000,
//        permissions: 16877,
//        atime: 1353269007,
//        mtime: 1353269007 } } ]
// SFTP :: Handle closed
// SFTP :: SFTP session closed

API

require('ssh2') returns a Connection object

Connection events

• connect() - A connection to the server was successful.

• banner(< string >message, < string >language) - A notice was sent by the server upon connection.

• ready() - Authentication was successful.

• tcp connection(< object >details, < function >accept, < function >reject) - An incoming forwarded TCP connection is being requested. Calling accept accepts the connection and returns a ChannelStream object. Calling reject rejects the connection and no further action is needed. details contains:

  • srcIP - string - The originating IP of the connection.

  • srcPort - integer - The originating port of the connection.

  • dstIP - string - The remote IP the connection was received on (given in earlier call to forwardIn()).

  • dstPort - integer - The remote port the connection was received on (given in earlier call to forwardIn()).

• keyboard-interactive(< string >name, < string >instructions, < string >instructionsLang, < array >prompts, < function >finish) - The server is asking for replies to the given prompts for keyboard-interactive user authentication. name is generally what you'd use as a window title (for GUI apps). prompts is an array of { prompt: 'Password: ', echo: false } style objects (here echo indicates whether user input should be displayed on the screen). The answers for all prompts must be provided as an array of strings and passed to finish when you are ready to continue. Note: It's possible for the server to come back and ask more questions.

• change password(< string >message, < string >language, < function >done) - If using password-based user authentication, the server has requested that the user's password be changed. Call done with the new password.

• error(< Error >err) - An error occurred. A 'level' property indicates 'connection-socket' for socket-level errors and 'connection-ssh' for SSH disconnection messages. In the case of 'connection-ssh' messages, there may be a 'description' property that provides more detail.

• end() - The socket was disconnected.

• close(< boolean >hadError) - The socket was closed. hadError is set to true if this was due to error.

Connection methods

• (constructor)() - Creates and returns a new Connection instance.

• connect(< object >config) - (void) - Attempts a connection to a server using the information given in config:

  • host - < string > - Hostname or IP address of the server. Default: ("127.0.0.1")

  • port - < integer > - Port number of the server. Default: 22

  • hostHash - < string > - 'md5' or 'sha1'. The host's key is hashed using this method and passed to the hostVerifier function. Default: (none)

  • hostVerifier - < function > - Function that is passed a string hex hash of the host's key for verification purposes. Return true to continue with the connection, false to reject and disconnect. Default: (none)

  • user - < string > - Username for authentication. Default: (none)

  • password - < string > - Password for password-based user authentication. Default: (none)

  • agent - < string > - Path to ssh-agent's UNIX socket for ssh-agent-based user authentication. Default: (none)

  • privateKey - < mixed > - Buffer or string that contains an unencrypted private key for key-based user authentication (OpenSSH format). Default: (none)

  • passphrase - < string > - For an encrypted private key, this is the passphrase used to decrypt it. Default: (none)

  • publicKey - < mixed > - Optional Buffer or string that contains a public key for key-based user authentication (OpenSSH format). If publicKey is not set, it will be generated from the privateKey. Default: (none)

  • tryKeyboard - < boolean > - Try keyboard-interactive user authentication if primary user authentication method fails. Default: false

  • pingInterval - < integer > - How often to send SSH-level keepalive packets to the server. Default: (no keepalive)

• exec(< string >command[, < object >environment], < function >callback) - (void) - Executes command on the server, with an optional environment set before execution. callback has 2 parameters: < Error >err, < ChannelStream >stream. For exec, the stream will also emit 'exit' when the process finishes. If the process finished normally, the process return value is passed to the 'exit' callback. If the process was interrupted by a signal, the following are passed to the 'exit' callback: null, < string >signalName, < boolean >didCoreDump, < string >description.

• shell([< object >window,] < function >callback) - (void) - Starts an interactive shell session on the server, with optional terminal window settings. Valid window properties include: rows (defaults to 24), cols (defaults to 80), height (in pixels, defaults to 480), width (in pixels, defaults to 640), and term (value to use for $TERM, defaults to 'vt100'). Rows and cols overrides width and height when rows and cols are non-zero. Pixel dimensions refer to the drawable area of the window. Zero dimension parameters are ignored. callback has 2 parameters: < Error >err, < ChannelStream >stream.

• forwardIn(< string >remoteAddr, < integer >remotePort, < function >callback) - (void) - Bind to remoteAddr on remotePort on the server and forward incoming connections. callback has 2 parameters: < Error >err, < integer >port (port is the assigned port number if remotePort was 0). Here are some special values for remoteAddr and their associated binding behaviors:

  • '' - Connections are to be accepted on all protocol families supported by the server.

  • '0.0.0.0' - Listen on all IPv4 addresses.

  • '::' - Listen on all IPv6 addresses.

  • 'localhost' - Listen on all protocol families supported by the server on loopback addresses only.

  • '127.0.0.1' and '::1' - Listen on the loopback interfaces for IPv4 and IPv6, respectively.

• unforwardIn(< string >remoteAddr, < integer >remotePort, < function >callback) - (void) - Unbind remoteAddr on remotePort on the server and stop forwarding incoming connections. Until callback is called, more connections may still come in. callback has 1 parameter: < Error >err.

• forwardOut(< string >srcIP, < integer >srcPort, < string >dstIP, < integer >dstPort, < function >callback) - (void) - Open a connection with srcIP and srcPort as the originating address and port and dstIP and dstPort as the remote destination address and port. callback has 2 parameters: < Error >err, < ChannelStream >stream.

• sftp(< function >callback) - (void) - Starts an SFTP (protocol version 3) session. callback has 2 parameters: < Error >err, < SFTP >sftpConnection.

• end() - (void) - Disconnects the socket.

ChannelStream

This is a normal duplex Stream, with the following changes:

• A boolean property 'allowHalfOpen' exists and behaves similarly to the property of the same name for net.Socket. When the stream's end() is called, if 'allowHalfOpen' is true, only EOF will be sent (the server can still send data if they have not already sent EOF). The default value for this property is false.

• For shell():

  • setWindow(< integer >rows, < integer >cols, < integer >height, < integer >width) - (void) - Lets the server know that the local terminal window has been resized. The behavior of these arguments is the same as described for shell().

• For shell() and exec():

  • 'data' events are passed a second (string) argument to the callback, which indicates whether the data is a special type. So far the only defined type is 'stderr'.

  • signal(< string >signalName) - (void) - Sends a POSIX signal to the current process on the server. Valid signal names are: 'ABRT', 'ALRM', 'FPE', 'HUP', 'ILL', 'INT', 'KILL', 'PIPE', 'QUIT', 'SEGV', 'TERM', 'USR1', and 'USR2'. Also, from the RFC: "Some systems may not implement signals, in which case they SHOULD ignore this message."

SFTP events

• end() - The SFTP session was ended.

SFTP methods

• end() - (void) - Ends the SFTP session.

• createReadStream(< string >path[, < object >options]) - ReadStream - Returns a new readable stream for path. options has the following defaults:

{ flags: 'r',
  encoding: null,
  mode: 0666,
  bufferSize: 64 * 1024
}

options can include 'start' and 'end' values to read a range of bytes from the file instead of the entire file. Both 'start' and 'end' are inclusive and start at 0. The encoding can be 'utf8', 'ascii', or 'base64'.

An example to read the last 10 bytes of a file which is 100 bytes long:

fs.createReadStream('sample.txt', {start: 90, end: 99});

• createWriteStream(< string >path[, < object >options]) - WriteStream - Returns a new writable stream for path. options has the following defaults:

{ flags: 'w',
  encoding: null,
  mode: 0666 }

options may also include a 'start' option to allow writing data at some position past the beginning of the file. Modifying a file rather than replacing it may require a flags mode of 'r+' rather than the default mode 'w'.

• open(< string >filename, < string >mode, [< ATTRS >attributes, ]< function >callback) - (void) - Opens a file filename for mode with optional attributes. mode is any of the modes supported by fs.open (except sync mode). callback has 2 parameters: < Error >err, < Buffer >handle.

• close(< Buffer >handle, < function >callback) - (void) - Closes the resource associated with handle given by open() or opendir(). callback has 1 parameter: < Error >err.

• read(< Buffer >handle, < Buffer >buffer, < integer >offset, < integer >length, < integer >position, < function >callback) - (void) - Reads length bytes from the resource associated with handle starting at position and stores the bytes in buffer starting at offset. callback has 3 parameters: < Error >err, < integer >bytesRead, < Buffer >buffer (offset adjusted).

• write(< Buffer >handle, < Buffer >buffer, < integer >offset, < integer >length, < integer >position, < function >callback) - (void) - Writes length bytes from buffer starting at offset to the resource associated with handle starting at position. callback has 1 parameter: < Error >err.

• fstat(< Buffer >handle, < function >callback) - (void) - Retrieves attributes for the resource associated with handle. callback has 2 parameters: < Error >err, < ATTRS >attributes.

• fsetstat(< Buffer >handle, < ATTRS >attrs, < function >callback) - (void) - Sets the attributes defined in attrs for the resource associated with handle. callback has 1 parameter: < Error >err.

• opendir(< string >path, < function >callback) - (void) - Opens a directory path. callback has 2 parameters: < Error >err, < Buffer >handle.

• readdir(< Buffer >handle, < function >callback) - (void) - Retrieves directory entries from the directory associated with handle. This function may need to be called multiple times to receive the entire directory listing. callback has 2 parameters: < Error >err, < mixed >list. list is either an Array of { filename: 'foo', longname: '....', attrs: {...} } style objects (attrs is of type ATTR) OR boolean false to indicate no more directory entries are available for the given handle.

• unlink(< string >path, < function >callback) - (void) - Removes the file/symlink at path. callback has 1 parameter: < Error >err.

• rename(< string >srcPath, < string >destPath, < function >callback) - (void) - Renames/moves srcPath to destPath. callback has 1 parameter: < Error >err.

• mkdir(< string >path, < function >callback) - (void) - Creates a new directory path. callback has 1 parameter: < Error >err.

• rmdir(< string >path, < function >callback) - (void) - Removes the directory at path. callback has 1 parameter: < Error >err.

• stat(< string >path, < function >callback) - (void) - Retrieves attributes for path. callback has 2 parameter: < Error >err, < ATTRS >attributes.

• lstat(< string >path, < function >callback) - (void) - Retrieves attributes for path. If path is a symlink, the link itself is stat'ed instead of the resource it refers to. callback has 2 parameters: < Error >err, < ATTRS >attributes.

• setstat(< string >path, < ATTRS >attributes, < function >callback) - (void) - Sets the attributes defined in attrs for path. callback has 1 parameter: < Error >err.

• readlink(< string >path, < function >callback) - (void) - Retrieves the target for a symlink at path. callback has 2 parameters: < Error >err, < string >target.

• symlink(< string >targetPath, < string >linkPath, < function >callback) - (void) - Creates a symlink at linkPath to targetPath. callback has 1 parameter: < Error >err.

• realpath(< string >path, < function >callback) - (void) - Resolves path to an absolute path. callback has 2 parameters: < Error >err, < string >absPath.

ATTRS

An object with the following valid properties:

• size - < integer > - Resource size in bytes.

• uid - < integer > - User ID of the resource.

• gid - < integer > - Group ID of the resource.

• permissions - < integer > - Permissions for the resource.

• atime - < integer > - UNIX timestamp of the access time of the resource.

• mtime - < integer > - UNIX timestamp of the modified time of the resource.