Sveiki, OSI lygyje mes turime lygi Network (Tinklo).
Sis lygis (kaip ir dauguma ju) ant siunciamo / perduodamo paketo uzdeda savo raktini vokeli, kad kitame kompiuteryje, tas pats lygmuo suprastu, ka daryti su siame voke esancia informacija. Sio vokelio turini galime perziureti pasitelkdami programele wireshark:
aptitude install wiresharkTaigi is ko susideda si antraste?
| b | it | a | i: | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 3 | 3 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
| Version | IHL | Type of service | Total Length | ||||||||||||||||||||||||||||
| Identification | Flags | Fragment Offset | |||||||||||||||||||||||||||||
| Time To Live | Protocol | Header checksum | |||||||||||||||||||||||||||||
| Source address | |||||||||||||||||||||||||||||||
| Destination address | |||||||||||||||||||||||||||||||
| Options (Optional) | |||||||||||||||||||||||||||||||
Lenteles reiksmes
Version:
4 - IP versija 4
Internet header length
32bitu zodziu kiekis IP antrasteje,
minimali reiksme: 5 (20 Baitu) ir
maksimali reiksme: 15 (60 Baitu)
| Type of service (PreDTRCx) | Differentiated Services |
|---|---|
| Precedence(000-111) | 000 |
| D (1 minimize delay) | 0 |
| T (1 maximize throughout) | 0 |
| R (1 maximize reliability) | 0 |
| C (1 minimize cost) | 1 = ECN capable |
| x (reserved and set to 0) | 1 = congestion experienced |
Total Length
Kiekis Baitu pakete. Maximalus dydis: 65535.
Flags (xDM)
x - rezervuotas ir yra 0
D = 1 - Nefragmentuoti
M = 1 - Daugiau fragmentu
Fragment Offset
Sio fragmento vieta originalioje deitagramoje (nepatinka man sis zodis) po 8 Baitus...
Protocol
1) ICMP
2) IGMP
6) TCP
9) IGRP
17) UDP
47) GRE
50) ESP
51) AH
57) SKIP
88) EIGRP
89) OSPF
115) L2TP
Header checksum
Tik IP antrastes kontroline suma
Adresai
Siuntejo (source) ir gavejo (destination) IP adresai
Options (0-40 Baitu; padded to 4-byte boundary)
0 - end of options list
1 - No operation (pad)
7 - Record route
68 - Timestamp
131 - Loose source route
137 - Strict source route
