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Handshake in TCP

3 way Handshake:

When TCP establishes the connection. Steps followed:
1) SYN packet is sent by A to B with a random sequence number(for initial seq. no.), say SYN 1000 as a request to establish the connection.
2) B sends ACK 1001 indicating to send the packet 1001 assuring the request to be accepted.
3) A sends ACK 1001 to indicate that it has received the request confirmation.

4 Way Handshake:

When there's a connection termination then 4 way handshake is used.
For termintation of connection in one direction:
1) FIN packet is sent
2) Other party acknowledges it
Similar process is followed for connection to end the other way as it's a full duplex connection.
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