c - Linux SOCK_RAW 和 SOCK_STREAM 有什么区别？

Question

我最近一直在研究网络与 c 代码和密码学，在思考随机问题时，我偶然发现了一段用于数据包嗅探的代码，我对函数 中使用的实际套接字有疑问从()接收()。套接字通过以下 sock 函数 rawSock = socket(AF_INET, SOCK_RAW, 0) 进行初始化。

我理解 SOCK_STREAM 和 SOCK_RAW 是表示整数的宏；但问题不在于值(value)观，而在于结果。

我什么时候可以使用 SOCK_STREAM 而不是 SOCK_RAW ，反之亦然？

我了解使用 SOCK_STREAM 的基本客户端和服务器通信。我正在使用 C 和 Linux

Answer 1

阅读man page .

原型(prototype)

int socket(int domain, int type, int protocol);

类型可以是

   SOCK_STREAM     Provides sequenced, reliable, two-way, connection-
                   based byte streams.  An out-of-band data transmission
                   mechanism may be supported.

或

   SOCK_RAW        Provides raw network protocol access.

在一行中，SOCK_STREAM 用于面向连接的套接字，其中底层操作系统创建和管理 L4 (TCP)、L3 和 L2 的 header 。 OTOH SOCK_RAW 提供了对 header 和数据包构造的更细粒度的控制，用户必须在其中构造和提供 header ，还可以管理内容。

详细说明:

Sockets of type SOCK_STREAM are full-duplex byte streams. They do not preserve record boundaries. A stream socket must be in a connected state before any data may be sent or received on it. A connection to another socket is created with a connect(2) call. Once connected, data may be transferred using read(2) and write(2) calls or some variant of the send(2) and recv(2) calls. When a session has been completed a close(2) may be performed. Out-of-band data may also be transmitted as described in send(2) and received as described in recv(2).

和

SOCK_RAW sockets allow sending of datagrams to correspondents named in sendto(2) calls. Datagrams are generally received with recvfrom(2), which returns the next datagram along with the address of its sender.