INITACK

INITACK stands for Initialization Acknowledgement. It is a control message used in some communication protocols to acknowledge and respond to an initialization request (INIT). The message typically indicates whether initialization can proceed and may carry negotiated parameters, a session identifier, and status information. In practice, INITACK is used during a handshake between two endpoints or between an application and a service to finalize setup parameters before normal operation begins.

In many protocols that implement a two-phase handshake, the client sends INIT with proposed settings; the responder replies with INITACK that either accepts the proposed settings, proposes alternatives, or reports an error. The INITACK may include a success status, a chosen protocol version, supported features, a session token, and limits such as timeouts or buffer sizes.

Fields and semantics vary by protocol, but common elements include a status code, a correlation or session ID, negotiated parameters, and optional data such as capability flags or error text. The message is usually transmitted with integrity protection and may be accompanied by nonce or sequence numbers to prevent replay.

Reliability: INITACK is typically part of an initialization sequence that must complete before subsequent messages are exchanged. If an INITACK is not received, the initiator may retransmit INIT or terminate the session according to the protocol rules.

Security and integrity considerations revolve around authentication of the responder, protection against replay, and ensuring that the agreed parameters match the capabilities of both sides. As with other handshake messages, proper validation of INITACK contents is critical to prevent misconfiguration or unauthorized access.