NegTokenResp

NegTokenResp is a data structure used in security protocols, particularly in the context of Kerberos authentication. It is a response token that is generated by a server when a client presents a Kerberos ticket that is deemed invalid or unacceptable by the server. The primary purpose of the NegTokenResp is to inform the client of the reason for the rejection and, in some cases, to offer alternative authentication methods.

This token is part of a challenge-response mechanism. When a client attempts to authenticate with a server using a Kerberos ticket, the server may validate the ticket. If the validation fails, the server can send back a NegTokenResp. This response typically contains information indicating the failure, such as an expired ticket, an incorrect principal, or a mismatch in security contexts.

The NegTokenResp can also be used to negotiate security mechanisms. If the client and server do not agree on the security protocols or mechanisms to be used, the NegTokenResp can suggest alternative options that the client can then attempt to use for re-authentication. This allows for a more flexible and resilient authentication process, especially in environments with diverse security requirements. The structure and contents of a NegTokenResp are defined by the relevant security standards, such as RFCs related to Kerberos.