网络报文格式
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一、802.3报文
RFC（1516）报文头定义
Header Format
Header
...--------+--------+--------+
MAC Header | 802.{3/4/5} MAC ...--------+--------+--------+
+--------+--------+--------+
| DSAP=K1| SSAP=K1| Control| 802.2 LLC +--------+--------+--------+
+--------+--------+---------+--------+--------+
|Protocol Id or Org Code =K2| EtherType | 802.2 SNAP +--------+--------+---------+--------+--------+
The total length of the LLC Header and the SNAP header is 8-octets, making the 802.2 protocol overhead come out on an nice boundary.
The K1 value is 170 (decimal).
The K2 value is 0 (zero).
The control value is 3 (Unnumbered Information).
报文样例
二、AH报文
RFC2402
IPV4 加入AH
BEFORE APPL YING AH
----------------------------
IPv4 |orig IP hdr | | |
|(any options)| TCP | Data |
----------------------------
AFTER APPL YING AH
---------------------------------
IPv4 |orig IP hdr | | | |
|(any options)| AH | TCP | Data |
---------------------------------
|<------- authenticated ------->|
except for mutable fields
报文样例
IPV6 AH报文
RFC 2402
BEFORE APPL YING AH
---------------------------------------
IPv6 | | ext hdrs | | |
| orig IP hdr |if present| TCP | Data |
---------------------------------------
AFTER APPL YING AH
------------------------------------------------------------
IPv6 | |hop-by-hop, dest*, | | dest | | | |orig IP hdr |routing, fragment. | AH | opt* | TCP | Data |
------------------------------------------------------------
|<---- authenticated except for mutable fields ----------->|
报文样例
AH隧道报文
------------------------------------------------
IPv4 | new IP hdr* | | orig IP hdr* | | |
|(any options)| AH | (any options) |TCP | Data |
------------------------------------------------
|<- authenticated except for mutable fields -->|
| in the new IP hdr |
--------------------------------------------------------------
IPv6 | | ext hdrs*| | | ext hdrs*| | | |new IP hdr* |if present | AH |orig IP hdr* |if present|TCP|Data|
--------------------------------------------------------------
|<-- authenticated except for mutable fields in new IP hdr ->|
* = construction of outer IP hdr/extensions and modification
of inner IP hdr/extensions is discussed below.
样例
三、L2TP RFC 2661
报文样例
四、PPTP报文
样例
五、TEREDO