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Chapter 2
Protocol Attributes
Sequence Number: 512
ICMP Data Area:
abcdefghijklmnop 61 62 63 64 65 66 67 68 69 6a 6b 6c
6d 6e 6f 70
qrstuvwabcdefghi 71 72 73 74 75 76 77 61 62 63 64 65
66 67 68 69
Frame Check Sequence: 0x342e3235
As with the IP packet structure, the ICMP structure is similar in that it has
a type, checksum, identifier, and sequence number. The names differ a little,
but have the same functionality.
Transport Control Protocol (TCP)
The Transport Control Protocol (TCP), a connection-oriented protocol on
the Transport layer that provides a reliable delivery of data, is an integral
part of the IP suite. Look at the structure of the TCP packet. The following
EtherPeek frame was taken during a POP3 transaction:
TCP - Transport Control Protocol
Source Port: 110 POP3
Destination Port: 1097
Sequence Number: 997270908
Ack Number: 7149472
Offset: 5
Reserved: %000000
Code: %010000
Ack is valid
Window: 8760
Checksum: 0x8064
Urgent Pointer: 0
No TCP Options
No More POP Command or Reply Data
Extra bytes (Padding):
UUUUUU 55 55 55 55 55 55
Frame Check Sequence: 0x04020000
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