WP_Filesystem_SSH2::connect()

	public function connect() {
		if ( ! $this->keys ) {
			$this->link = @ssh2_connect($this->options['hostname'], $this->options['port']);
		} else {
			$this->link = @ssh2_connect($this->options['hostname'], $this->options['port'], $this->options['hostkey']);
		}

		if ( ! $this->link ) {
			$this->errors->add( 'connect',
				/* translators: %s: hostname:port */
				sprintf( __( 'Failed to connect to SSH2 Server %s' ),
					$this->options['hostname'] . ':' . $this->options['port']
				)
			);
			return false;
		}

		if ( !$this->keys ) {
			if ( ! @ssh2_auth_password($this->link, $this->options['username'], $this->options['password']) ) {
				$this->errors->add( 'auth',
					/* translators: %s: username */
					sprintf( __( 'Username/Password incorrect for %s' ),
						$this->options['username']
					)
				);
				return false;
			}
		} else {
			if ( ! @ssh2_auth_pubkey_file($this->link, $this->options['username'], $this->options['public_key'], $this->options['private_key'], $this->options['password'] ) ) {
				$this->errors->add( 'auth',
					/* translators: %s: username */
					sprintf( __( 'Public and Private keys incorrect for %s' ),
						$this->options['username']
					)
				);
				return false;
			}
		}

		$this->sftp_link = ssh2_sftp( $this->link );
		if ( ! $this->sftp_link ) {
			$this->errors->add( 'connect',
				/* translators: %s: hostname:port */
				sprintf( __( 'Failed to initialize a SFTP subsystem session with the SSH2 Server %s' ),
					$this->options['hostname'] . ':' . $this->options['port']
				)
			);
			return false;
		}

		return true;
	}