CodeIgniter-来自本地主机的“ ldap_bind（）：无法绑定到服务器：无法联系LDAP服务器”

Question

我必须使用CodeIgniter 3处理用PHP 5.5编写的旧应用程序。

对于身份验证，它使用具有Auth_AD库的专用服务器的ldap连接。

在生产服务器和测试服务器中，此ldap连接成功运行，但是当我尝试从localhost进行身份验证时，出现此错误

A PHP Error was encountered

Severity: Warning

Message: ldap_bind(): Unable to bind to server: Can't contact LDAP server

Filename: libraries/Auth_AD.php

Line Number: 388

所有地方的凭据都完全相同。

以下是在第388行调用的函数（第一次ldap_bind（）调用）：

private function bind_ad()
    {
      // preset the continuation marker
        $continue = true;

        // attempt to connect to each of the AD servers, stop if a connection is succesful
        foreach ($this->_hosts as $host) {
            $this->_ldap_conn = ldap_connect($host);
            if ($this->_ldap_conn) {
                break;
            } else {
                log_message('info', 'Auth_AD: Error connecting to AD server ' . $host);
            }
        }

        // check for an active LDAP connection
        if (!$this->_ldap_conn) {
            log_message('error', "Auth_AD: unable to connect to any AD servers.");
            show_error('Error connecting to any Active Directory server(s). Please check your configuration and connections.');
            $continue = false;
        }

        if ($continue) {
            // set some required LDAP options
            ldap_set_option($this->_ldap_conn, LDAP_OPT_REFERRALS, 0);
            ldap_set_option($this->_ldap_conn, LDAP_OPT_PROTOCOL_VERSION, 3);

            // attempt to bind to the AD using the proxy user or anonymously if no user was configured
            if ($this->_proxy_user != null) {
                ldap_bind($this->_ldap_conn, $this->_proxy_user, $this->_proxy_pass);
            } else {
                $bind = ldap_bind($this->_ldap_conn);
            }

            // verify the LDAP binding
            if (!$bind) {
                if ($this->_proxy_user != null) {
                    log_message('error', 'Auth_AD: Unable to perform LDAP bind using user ' . $this->_proxy_user);
                    show_error('Unable to bind (i.e. login) to the AD for user ID lookup');
                } else {
                    log_message('error', 'Auth_AD: Unable to perform anonymous LDAP bind.');
                    show_error('Unable to bind (i.e. login) to the AD for user ID lookup');
                }

                $continue = false;
            } else {
                log_message('debug', 'Auth_AD: Successfully bound to AD. Performing DN lookup for user');
            }
        }

        // return the result
        return $continue;
    }

我认为这不是代码问题，因为在本地主机或生产环境中，代码库是相同的，并且可以正常工作。有什么想法吗？