net -t struct ifreq

结构原型:

struct ifreq
{
#define IFHWADDRLEN 6
 union
 {
  char ifrn_name[IFNAMSIZ];  
 } ifr_ifrn;
 
 union {
  struct sockaddr ifru_addr;
  struct sockaddr ifru_dstaddr;
  struct sockaddr ifru_broadaddr;
  struct sockaddr ifru_netmask;
  struct  sockaddr ifru_hwaddr;
  short ifru_flags;
  int ifru_ivalue;
  int ifru_mtu;
  struct  ifmap ifru_map;
  char ifru_slave[IFNAMSIZ]; 
  char ifru_newname[IFNAMSIZ];
  void __user * ifru_data;
  struct if_settings ifru_settings;
 } ifr_ifru;
};

#define ifr_name ifr_ifrn.ifrn_name 
#define ifr_hwaddr ifr_ifru.ifru_hwaddr 
#define ifr_addr ifr_ifru.ifru_addr 
#define ifr_dstaddr ifr_ifru.ifru_dstaddr 
#define ifr_broadaddr ifr_ifru.ifru_broadaddr 
#define ifr_netmask ifr_ifru.ifru_netmask 
#define ifr_flags ifr_ifru.ifru_flags 
#define ifr_metric ifr_ifru.ifru_ivalue 
#define ifr_mtu  ifr_ifru.ifru_mtu 
#define ifr_map  ifr_ifru.ifru_map 
#define ifr_slave ifr_ifru.ifru_slave 
#define ifr_data ifr_ifru.ifru_data 
#define ifr_ifindex ifr_ifru.ifru_ivalue 
#define ifr_bandwidth ifr_ifru.ifru_ivalue    
#define ifr_qlen ifr_ifru.ifru_ivalue 
#define ifr_newname ifr_ifru.ifru_newname 
#define ifr_settings ifr_ifru.ifru_settings 

  

基本介绍: 

ifreq结构定义在/usr/include/net/if.h,用来配置ip地址,激活接口,配置MTU等接口信息的。其中包含了一个接口的名 字和具体内容——(是个共用体,有可能是IP地址,广播地址,子网掩码,MAC号,MTU或其他内容)。ifreq包含在ifconf结构中。而 ifconf结构通常是用来保存所有接口的信息的。

 

举例说明:

在Linux系统中,ifconfig命令是通过ioctl接口与内核通信,例如,当系统管理员输入如下命令来改变接口eth0的MTU大小:

    ifconfig eth0 mtu 1250

ifconfig命令首先打开一个socket,然后通过系统管理员输入的参数初始化一个数据结构,并通过ioctl调用将数据传送到内核。SIOCSIFMTU是命令标识符。

    struct ifreq data;
    fd = socket(PF_INET, SOCK_DGRAM, 0);
    < ... initialize "data" ...>
    err = ioctl(fd, SIOCSIFMTU, &data);

转载于:https://www.cnblogs.com/pencil-zh/p/4514706.html

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