Decoding an IP Header (1)

1
Decoding an IP Header (1)
0x45 Version 4, IHL 5
0x00 ToS 0 (not set)
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
IP Version Length 4 bits Offset 0 bits
IP Header Length (IHL) Length 4 bits Offset 4
bits
Type of Service (ToS) Length 1 byte Offset 1
byte
2
Decoding an IP Header (2)
0x0034 Length 52 bytes
0xc9e7 IPID 51687
0x3d TTL 61
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
Total Packet Length Length 2 bytes Offset 2
bytes
IP Identification (IPID) Length 2 bytes Offset
4 bytes
Time to Live (TTL) Length 1 byte Offset 8 bytes
3
Decoding an IP Header (3)
0x4000 0100 0000 0000 0000Flags 010 (Dont
Fragment set)Fragment Offset 0s (not set)
0x06 Embedded Protocol 6 (TCP)
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
IP Header Flags Length 3 bits Offset 6 bytes
Fragment Offset Length 13 bits Offset 6 bytes
3 bits
Embedded Protocol Length 1 byte Offset 9 bytes
4
Decoding an IP Header (4)
0xd8 0x23 0xd9 0xba 216 35 217
186 Source Address
0x178c Checksum 62216
0xac 0x10 0x00 0xb7 172 16 0
183 Destination Address
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
Checksum Length 2 bytes Offset 10 bytes
Source Address Length 4 bytes Offset 12 bytes
Destination Address Length 4 bytes Offset 16
bytes
5
Decoding a TCP Header (1)
0x729a2105 Sequence number 1922703621
0x0017 Source Port 23
0x12f5 Dest. Port 4853
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
Source Port Length 2 bytes Offset 0 bytes
Destination Port Length 2 bytes Offset 2 bytes
Sequence Number Length 4 bytes Offset 4 bytes
6
Decoding a TCP Header (2)
0x60 0110 0000 Header Len 0110 6
0x145cdb4f ACK number 341629775
0xa7cb Checksum 42955
0x18 0001 1000 Flags PSH, ACK
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
Header LengthLength 4 bits Offset 12 bytes
TCP Flags Length 1 byte Offset 13 bytes
ACK Number Length 4 bytes Offset 8 bytes
Checksum Length 2 bytes Offset 16
7
Decoding a TCP Header (3)
0x020405b4 0x02 MSS set, 0x04 4 bytes 0x05b4
MSS is 1460 bytes
0x16d0 Window size 5840
0x0000 Urgent Ptr 0 (not set)
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
TCP Window Size Length 2 bytes Offset 14 bytes
Urgent Ptr Length 2 bytes Offset 18 bytes
TCP Options Length variable Offset 20 bytes
Data Length variable Offset variable
8
Decoding a TCP Header (4)
(TCP Header Length - Min. TCP Header Length)
TCP Options Length (6 4) -
20 4
IP Total Length - (IHL TCP Header Length)
Payload Length 52 -
((5 4) (6 4)) 8
4500 0034 c9e7 4000 3d06 178c d823 d9ba ac10 00b7
0017 12f5 729a 2105 145c db4f 6018 16d0 a7cb 0000
0204 05b4 6c73 202d 6c61 0000
0x020405b4 0x02 MSS set, 0x04 4 bytes 0x05b4
MSS is 1460 bytes
TCP Options Length 4 bytes Offset 20 bytes
Payload Length 8 Offset 24 bytes