BIG-IQ Rest API: basic authentication failure

Hello,

 

Please bare with me as I'm new to F5 product. I ran into authentication failure when attempting to make a Rest API call to the Big-IQ. Here are what happening: after bringing up a Big-IQ VM, I was able to login and apply the license to activate it. I was able to navigate through pages in the GUI. However, when I attempted to make a simple Rest API call using the same username/password to login to the GUI, it always failed with "401 Authorization Required". Nothing fancy, I'm using the basic authentication as following:

 

$ curl -k -u admin:admin -H "Content-Type:application/json" -X GET

 

 

 

401 Authorization Required

 

 

webd

 

I tried different API and got the same error. I also tried to Base64 encode the credentials and explicitly specified it as an HTTP header, but it failed the same way:

 

$ curl -k -H "Authorization: Basic YWRtaW46YWRtaW4=" -H "Content-Type:application/json" -X GET

 

Did I miss something in order to grant API access permission for the account? Btw, I'm using a trial license and the account has Administrator role. Thanks in advance!