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Update 'Test_Cases/Test_Case1/readme'

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Sana147 2023-05-08 00:18:17 +00:00
parent 91d9bb1b37
commit d06054386c
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Test_Cases/Test_Case1/readme
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@ -5,7 +5,7 @@ The values for the header fields are:
1. Verison = 4, to indicate IPv4 version is used. 1. Verison = 4, to indicate IPv4 version is used.
2. IHL = 5, which indicates 20 bytes. 2. IHL = 5, which indicates 20 bytes.
3. Type of Service = 0, 3. Type of Service = 0,
4. Total Window size = 40, which is 28 in hex. The total windows size contains the total lenght of IP header plus data. 4. Total Length = 40, which is 28 in hex. The total windows size contains the total lenght of IP header plus data.
5. Identification = 0001, 5. Identification = 0001,
6. Flags = All flags are set to zero, 6. Flags = All flags are set to zero,
7. Fragment Offset = For now, there is no fragment offset so, this value is set to 0. 7. Fragment Offset = For now, there is no fragment offset so, this value is set to 0.
@ -28,6 +28,32 @@ For the FIN+ACK packet, the FIN and ACK flags in the header have a value of 1.
(i) Concatenate TCP Pseudo header (Protocol, Source IP, Destination IP, Total Length) with TCP header and TCP data. This creates a big integer. (i) Concatenate TCP Pseudo header (Protocol, Source IP, Destination IP, Total Length) with TCP header and TCP data. This creates a big integer.
(ii) Convert this integer to binary and compute bit wise 1's complement. (ii) Convert this integer to binary and compute bit wise 1's complement.
The value of header comes out to be:
header = {}
header[0] = 0x45, Version, IHL
header[1] = 0x00, TOS,
header[2] = 0x00, Total Length,
header[3] = 0x28, Total Length,
header[4] = 0x00, Identification,
header[5] = 0x01, Identification,
header[6] = 0x00, Flags + Fragment Offset,
header[7] = 0x00, Flags + Fragment Offset,
header[8] = 0x28, TTL
header[9] = 0x06, Protocol
header[10] = 0x00, Header Checksum
header[11] = 0x00, Header Checksum
header[12] = 0xc8, Source IP,
header[13] = 0xcc, Source IP,
header[14] = 0x0a, Source IP,
header[15] = 0x0c, Source IP,
header[16] = 0xc8, Source IP,
header[17] = 0xcc, Source IP,
header[18] = 0x0a, Source IP,
header[19] = 0x0e, Source IP,
References: References:
1. https://www.thegeekstuff.com/2012/05/ip-header-checksum/ 1. https://www.thegeekstuff.com/2012/05/ip-header-checksum/
2. https://www.tutorialspoint.com/calculation-of-tcp-checksum 2. https://www.tutorialspoint.com/calculation-of-tcp-checksum