The ssh2_auth_password function can be used to authenticate to an SSH server from PHP with a username and password. Before using the ssh2_auth_password function, you will need to establish a connection to the SSH server using the ssh2_connection function.

In this example, username "john.doe" and password "itsasecret" are used to authenticate to the SSH server.

<?php
  $server = "server1.example.com";
  $connection = ssh2_connect($server, 22);

  if (!$connection) {
    echo "Failed to connect to SSH server $server <br />";
  }
  else {
    echo "Successfully connect to SSH server $server <br />";
  }

  $username = "john.doe";
  $password = "itsasecret";
  $authenticate = ssh2_auth_password($connection, $username, $password);

  if (!$authenticate) {
    echo "Failed to authenticate to SSH server $server as $username <br />";
  }
  else {
    echo "Successfully authenticated to SSH server $server as $username <br /";
  }
?>