7: TCP (Telnet) ACK

This is one of a series of 9 packets corresponding to the setup and clear-down of a TCP connection. In this case the conenction was made to the telent (terminal) port of the remote computer. The computer accepts the connection and produces a login prompt to the client. Instead of proceeding to login to the server, the client then decides to terminate the connection.

This packet acknowledges receipt of the previous TCP data sent from the client.


Hexadecimal Dump of the Packet

           0: 0800 2086 354b 00e0 f726 3fe9 0800 4500    .. .5K..÷&?...E.
          16: 0028 aafd 0000 fc06 3a56 8b85 e902 8b85    .(....ü.:V......
          32: d96e 0017 9005 9431 1028 7214 f130 5010    .n.....1.(r..0P.
          48: 2238 1c65 0000 0000 0010 0000              "8.e........


Decode of the Packet

ETHER:  ----- Ether Header -----
ETHER:
ETHER:  Packet 7 arrived at 17:37:24.00
ETHER:  Packet size = 60 bytes
ETHER:  Destination = 8:0:20:86:35:4b, Sun
ETHER:  Source      = 0:e0:f7:26:3f:e9, CISCO Router
ETHER:  Ethertype = 0800 (IP)
ETHER:
IP:   ----- IP Header -----
IP:
IP:   Version = 4
IP:   Header length = 20 bytes
IP:   Type of service = 0x00 (normal)
IP:   Total length = 40 bytes
IP:   Identification = 43773
IP:   Flags = 0x0
IP:         .0.. .... = may fragment
IP:         ..0. .... = last fragment
IP:   Fragment offset = 0 bytes
IP:   Time to live = 252 seconds/hops
IP:   Protocol = 6 (TCP)
IP:   Header checksum = 3a56
IP:   Source address = 139.133.233.2, server.abdn.ac.uk
IP:   Destination address = 139.133.217.110, client
IP:   No options
IP:
TCP:  ----- TCP Header -----
TCP:
TCP:  Source port = 23
TCP:  Destination port = 36869
TCP:  Sequence number = 2486243368
TCP:  Acknowledgement number = 1913975088
TCP:  Data offset = 20 bytes
TCP:  Flags = 0x10
TCP:        ..0. .... = No urgent pointer
TCP:        ...1 .... = Acknowledgement
TCP:        .... 0... = No push
TCP:        .... .0.. = No reset
TCP:        .... ..0. = No Syn
TCP:        .... ...0 = No Fin
TCP:  Window = 8760
TCP:  Checksum = 0x1c65
TCP:  Urgent pointer = 0
TCP:  No options
TCP:



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