IPv4 - ARP

IPv4 - ARP

課程影片

man 可以參考 arp(8) 或 arping(8)。另外，netfilters 中有 ARP 的 hook，命令列工具方面，nft 也整合了舊有的 arptables 功能。所以那些 *tables 可以考慮直接參考新的 nft 中與 ARP 有關的功能。

另外，在 IPv6 中，在 IPv4 中的 ARP 該具有的功能整合進了 ICMPv6 中的 Neighbor Discovery 中

arp for Showing Address Resolution Table in Linux

Image Not Showing Possible Reasons

The image file may be corrupted
The server hosting the image is unavailable
The image path is incorrect
The image format is not supported

第 7LMN 講路由器運作原理以及網路互連技術 L07 12 13 14

Image Not Showing Possible Reasons

The image file may be corrupted
The server hosting the image is unavailable
The image path is incorrect
The image format is not supported

目標：已知 IP，求 MAC 位址

ARP 封包格式

請求方

        0        7        15       23       31
        +--------+--------+--------+--------+
        |       HT        |        PT       |
        +--------+--------+--------+--------+
        |  HAL   |  PAL   |        OP       |
        +--------+--------+--------+--------+
        |         S_HA (bytes 0-3)          |
        +--------+--------+--------+--------+
        | S_HA (bytes 4-5)|S_L32 (bytes 0-1)|
        +--------+--------+--------+--------+
        |S_L32 (bytes 2-3)|S_NID (bytes 0-1)|
        +--------+--------+--------+--------+
        |         S_NID (bytes 2-5)         |
        +--------+--------+--------+--------+
        |S_NID (bytes 6-7)| T_HA (bytes 0-1)|
        +--------+--------+--------+--------+
        |         T_HA (bytes 3-5)          |
        +--------+--------+--------+--------+
        |         T_L32 (bytes 0-3)         |
        +--------+--------+--------+--------+
        |         T_NID (bytes 0-3)         |
        +--------+--------+--------+--------+
        |         T_NID (bytes 4-7)         |
        +--------+--------+--------+--------+

回覆方

        0        7        15       23       31
        +--------+--------+--------+--------+
        |       HT        |        PT       |
        +--------+--------+--------+--------+
        |  HAL   |  PAL   |        OP       |
        +--------+--------+--------+--------+
        |         S_HA (bytes 0-3)          |
        +--------+--------+--------+--------+
        | S_HA (bytes 4-5)|S_L32 (bytes 0-1)|
        +--------+--------+--------+--------+
        |S_L32 (bytes 2-3)|S_NID (bytes 0-1)|
        +--------+--------+--------+--------+
        |         S_NID (bytes 2-5)         |
        +--------+--------+--------+--------+
        |S_NID (bytes 6-7)| T_HA (bytes 0-1)|
        +--------+--------+--------+--------+
        |         T_HA (bytes 3-5)          |
        +--------+--------+--------+--------+
        |         T_L32 (bytes 0-3)         |
        +--------+--------+--------+--------+
        |         T_NID (bytes 0-3)         |
        +--------+--------+--------+--------+
        |         T_NID (bytes 4-7)         |
        +--------+--------+--------+--------+