第470页 网络与套接字

#include <sys/socket.h>
int listener_d = socket(PF_INET, SOCK_STREAM, 0);
if (listener_d == -1)
    error("无法打开套接字");

这里 socket 中的参数 PF_INET 难道不应该是 AF_INET 吗？（写过其他语言的 socket 程序）

然后去查手册 http://man7.org/linux/man-pages/man2/socket.2.html
 The manifest constants used under 4.x BSD for protocol families are
  PF_UNIX, PF_INET, and so on, while AF_UNIX, AF_INET, and so on are
  used for address families.  However, already the BSD man page
  promises: "The protocol family generally is the same as the address
  family", and subsequent standards use AF_* everywhere.

BSD 用的是 PF_  作为协议的前缀名 ，linux 则用的是AF_ 

看来作者使用的应该是MAC