Packet Headers

 

In the attached file what is the overhead percentage for each packet? (ratio of the rest of the packet to the payload) overhead bytes/total bytes
42/144=.292

34/83 = .410


What is the size of the udp header? 8 bytes

How do you determine the size of the TCP headers?

3rd row first hex character is the size of the TCP header

5 hex = 5 decimal * 32bits = 5 * (32 bits/8 bits/byte) = 5 * 4 bytes = 20 bytes

How do you determine the size of the payload?

Payload = Packet size - header

Payload = length + LLC (14) - header

102 =130 + 14 - 42

 

Total = hex 82 + 14 LLC header = 144
 

Headers 14, 20, 8 = 42
 

18:10:56.364297 eth0 > 0:0:0:0:0:0 199.14.59.166 ip 144: 199.17.59.166.telnet >
66.188.165.185.hello: P 4049840617:4049840707(90) ack 1070650057 win 5840 (DF) [
tos 0x10]
          4510 0082 133c 4000 4006 3bfd c711 3ba6
          42bc a5b9 0017 06fc f163 a9e9 3fd0 d2c9
          5018 16d0 9a6b 0000 0d0a 4b65 726e 656c
          2066 696c 7465 722c 2070 726f 746f 636f
          6c20 414c 4c2c 2064 6174 6167 7261 6d20
          7061 636b 6574 2073 6f63 6b65 740d 0a74
          6370 6475 6d70 3a20 6c69 7374 656e 696e
          6720 6f6e 2061 6c6c 2064 6576 6963 6573
          0d0a

17:30:26.880476 lo > 0:0:0:0:0:0 0:0:0:0:0:0 ip 83: underdark.1761 > underdark
.domain: 15703+ PTR? 85.1.0.224.in-addr.arpa. (41) (DF)
          4500 0045 f428 4000 4011 4110 c711 3ba6
          c711 3ba6 06e1 0035 0031 6a2b 3d57 0100
          0001 0000 0000 0000 0238 3501 3101 3003
          3232 3407 696e 2d61 6464 7204 6172 7061
          0000 0c00 01

 

Header LLC = 14

            IP = 20

            TCP = 0

                       34 total

E^@ ^@ E .. ( @^@ @^Q A^P ..^Q ;..
..^Q ;.. ^F.. ^@ 5 ^@ 1 j + = W ^A^@
^@^A ^@^@ ^@^@ ^@^@ ^B 8 5^A 1^A 0^C
2 2 4^G i n - a d d r^D a r p a
^@^@ ^L^@ ^A

 

 


 

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