# Anonymous User
You don't have to authenticate to RIPE Atlas at all. You can simply send a request and you will get a response. In this case, you are using the API as an anonymous user.
If an anonymous user does not have the right permissions to view the resource requested, the response will be a HTTP 403 error with a JSON object holding the error message.
Furthermore, some objects in the response will be obfuscated or left out completely for anonymous users. These restrictions are mainly due to privacy concerns for the people and organisations hosting the probes.
# Obfuscation of Geographical Data
Probe locations are obfuscated for all RIPE Atlas users. The obfuscation consists of dropping some accuracy from the geographical coordinates supplied by the probe hosts and then spreading them a bit to avoid having multiple overlapping probes. The location provided by the API will be within 80 to 400 metres of the actual location known to RIPE Atlas.
# Restricted Fields
The probes' IP addresses are only shown if the probe is public. If the probe is non-public, then the IP address is only available to the probe host. If the IP prefixes are known to RIPE Atlas, they will be visible to all users.
# Public Objects
Both Probe and Measurement objects can be public. If so, they will have a field called is_public set to "true". Anonymous users can only see public objects.