How Do I Get By The Basic Authentication Handshake When Using Fiddler To Test A WCF REST Service?
You need to base64 encode your username:password and then prefix it with Basic. It will end up looking something like:
Authorization: Basic VEFWSVNcZGFycmVsOg==
You then enter this in the request headers field.
来源：https://stackoverflow.com/questions/4947781/how-do-i-get-by-the-basic-authentication-handshake-when-using-fiddler-to-test-a