These may vary according to the demands of the client and server-i.e., there are several possible procedures to set up the connection. It defines the messages formatting or containing this information and the order of their exchange. This protocol is used to exchange all the information required by both sides for the exchange of the actual application data by TLS. When a Transport Layer Security (SSL or TLS) connection starts, the record encapsulates a "control" protocol-the handshake messaging protocol (content type 22). Main article: Transport Layer Security § TLS handshake It includes handshaking to negotiate authentication, encryption and maximum message size. The Simple Mail Transfer Protocol (SMTP) is the key Internet standard for email transmission. The reason for the client and server not using a default sequence number such as 0 for establishing the connection is to protect against two incarnations of the same connection reusing the same sequence number too soon, which means a segment from an earlier incarnation of a connection might interfere with a later incarnation of the connection. In this setup, the synchronize messages act as service requests from one server to the other, while the acknowledgement messages return to the requesting server to let it know the message was received. The first host (Alice) sends the second host (Bob) a "synchronize" (SYN) message with its own sequence number x, which Bob receives and to which he doesn't need to reply.Handshaking facilitates connecting relatively heterogeneous systems or equipment over a communication channel without the need for human intervention to set parameters.Įstablishing a normal TCP connection requires three separate steps: Ī simple handshaking protocol might only involve the receiver sending a message meaning "I received your last message and I am ready for you to send me another one." A more complex handshaking protocol might allow the sender to ask the receiver if it is ready to receive or for the receiver to reply with a negative acknowledgement meaning "I did not receive your last message correctly, please resend it" (e.g., if the data was corrupted en route). In place of the term "handshake", FTP RFC 3659 substitutes the term "conversation" for the passing of commands. One exception is Transport Layer Security, TLS, setup, FTP RFC 4217. For example, the term "handshake" is not present in RFCs covering FTP or SMTP. However, within TCP/IP RFCs, the term "handshake" is most commonly used to reference the TCP three-way handshake. Handshaking is a technique of communication between two entities. Handshaking can negotiate parameters that are acceptable to equipment and systems at both ends of the communication channel, including information transfer rate, coding alphabet, parity, interrupt procedure, and other protocol or hardware features. For example, when a computer communicates with another device such as a modem, the two devices will signal each other that they are switched on and ready to work, as well as to agree to which protocols are being used. Signals are usually exchanged between two devices to establish a communication link. The handshaking process usually takes place in order to establish rules for communication when a computer attempts to communicate with another device. In telecommunications, a handshake is an automated process of negotiation between two participants (example " Alice and Bob") through the exchange of information that establishes the protocols of a communication link at the start of the communication, before full communication begins. An example is the handshaking between a hypervisor and an application in a guest virtual machine. In computing, a handshake is a signal between two devices or programs, used to, e.g., authenticate, coordinate. Further details may exist on the talk page. Please expand the article to include this information. This article is missing information about Handshaking in, e.g., buses, software.
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