NTLM (NT LAN Manager) authentication is a native Windows authentication protocol developed and supported by Microsoft.When Apache NTLM authentication is enabled, the Web browser client can be authenticated based on this Windows authentication protocol.
For Internet Explorer clients, NTLM provides a silent authentication method that can be used in configurations where Kerberos authentication is not possible. For other Web browsers, such as Firefox, NTLM provides a “challenge/response” mechanism that avoids sending passwords in clear text.
- The Web page, Web directory, virtual Web site, or entire Web site must be configured to be protected with NTLM authentication.
- The client browser must be one that supports NTLM authentication, such as Internet Explorer and Firefox browsers.See Configuring Firefox to allow silent authentication to learn how to configure Internet Explorer and Firefox to use NTLM for silent authentication.