Hi,
Your Authentication header is improperly sent.
Please run
curl -v https://user:password@rabbitmq01:15671/api/aliveness-test/%2F
and simply re-use the authentication header as built by curl.
With user:password
string, it would be:
option httpchk get /api/aliveness-test/%2F HTTP/1.1\r\nAuthorization:\ Basic\ dXNlcjpwYXNzd29yZA==