TCP flags

SYN
Syn packet, a session establishment request. The first part of any TCP connection.
ACK
Ack packet, used to acknowledge the receipt of data from the sender. May appear in conjunction with other flags.
FIN
Finish flag, used to indicate the sender's intention to terminate the connection to the receiving host.
RESET (RST)
Indicates the sender's intention to immediately abort the existing connection.
PUSH (PSH)
Signals the immediate push of data from the sending host to the receiving host. For interactive applications such as telnet, the main issue is the quickest response time, which this "push" flag signals.
URGENT (URG)
Urgent data should take precedence over other data. For example, a Ctrl-C to terminate a FTP download.
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