Bad Request: The request was malformed.
Bad Request: The request was malformed. The client SHOULD NOT retry the request without modification from the previous attempt. The server may not be able to generate a valid MESSAGE-INTEGRITY for this error, so the client MUST NOT expect a valid MESSAGE-INTEGRITY attribute on this response.
Server Error: The server has suffered a temporary error.
Server Error: The server has suffered a temporary error. The client should try again.
Stale Nonce: The NONCE used by the client was no longer valid.
Stale Nonce: The NONCE used by the client was no longer valid. The client should retry, using the NONCE provided in the response.
Try Alternate: The client should contact an alternate server for this request.
Try Alternate: The client should contact an alternate server for this request. This error response MUST only be sent if the request included a USERNAME attribute and a valid MESSAGE- INTEGRITY attribute; otherwise, it MUST NOT be sent and error code 400 (Bad Request) is suggested. This error response MUST be protected with the MESSAGE-INTEGRITY attribute, and receivers MUST validate the MESSAGE-INTEGRITY of this response before redirecting themselves to an alternate server.
Note: Failure to generate and validate message integrity for a 300 response allows an on-path attacker to falsify a 300 response thus causing subsequent STUN messages to be sent to a victim.
Unauthorized: The request did not contain the correct credentials to proceed.
Unauthorized: The request did not contain the correct credentials to proceed. The client should retry the request with proper credentials.
Unknown Attribute: The server received a STUN packet containing a comprehension-required attribute that it did not understand.
Unknown Attribute: The server received a STUN packet containing a comprehension-required attribute that it did not understand. The server MUST put this unknown attribute in the UNKNOWN- ATTRIBUTE attribute of its error response.