Connect to SFTP using PHP and private key

Question

I have read article after article and just cannot find "the solution" that works for what I have.

I am trying to upload files via SFTP using php scripting. I have connected using CyberDuck successfully, but I need to do this programatically.

I have a .PPK file from the vendor that I used in CyberDuck. I have a username. I have the hostname. If I open the PPK file I see some Public Lines, Private Lines and Private-MAC.

Is there anyway I can access the server to do what I need to do using the information I have?

Here is the code I was playing with:

<?php if (!function_exists("ssh2_connect")) die("function ssh2_connect doesn't exist");
?>
<?php
$conn = ssh2_connect('hostname.com', 22);
echo $conn;
ssh2_auth_pubkey_file($conn,'USERNAME','/var/www/html/FILENAME.PPK');

// send a file
ssh2_scp_send($conn, '/var/www/html/FILETOSEND.TXT', 'FILETOSEND.TXT', 0644);
?>

I don't receive any errors but the file doesn't show up on the server. I can confirm that SSH2 is installed on my webhost.

Thanks for any help you can provide.

Answer 1

The question is quite old, but as I was looking for exactly the same answer, here is what I managed to gather.

First: Change key format from .ppk to .pem

.pkk keys are PuTTY format private key.

If you want to change that to .pem format, you need to install putty-tools with:

sudo apt install putty-tools

(On a Mac, install putty package with homebrew. For Windows, I have no clue.)

Then you can change the format of the key:

puttygen privatekey.ppk -O private-openssh -o privatekey.pem

Just in case you want to extract the public key from that private key, (you won't need for the rest of that answer, but just in case) it is quite easy:

openssl rsa -in privatekey.pem -pubout > publickey.pub

Second: Login with sFTP

Now that you have the privatekey.pem, you can use phpseclib to connect via SFTP. First, install phpseclib with Composer:

composer require phpseclib/phpseclib

Then in PHP:

require "vendor/autoload.php";

use phpseclib\Crypt\RSA;
use phpseclib\Net\SFTP;

$sftp = new SFTP('sftp.server.com');

// create new RSA key
$privateKey = new RSA();

// in case that key has a password
$privateKey->setPassword('private key password');

// load the private key
$privateKey->loadKey(file_get_contents('/path/to/privatekey.pem'));

// login via sftp
if (!$sftp->login('username', $privateKey)) {
    throw new Exception('sFTP login failed');
}

// now you can list what's in here
$filesAndFolders = $sftp->nlist();

// you can change directory
$sftp->chdir('coolstuffdir');

// get a file
$sftp->get('remoteFile', 'localFile');

// create a remote new file with defined content
$sftp->put('newfile.txt', 'new file content');

// put a local file
$sftp->put('remote.txt', 'local.txt', NET_SFTP_LOCAL_FILE);

If you want more info, go to the phpseclib sFTP feature list.