混杂模式

1、指一台机器的网卡能够接收所有经过它的数据包，而不论其目的地址是否是它。

2、一般计算机网卡都工作在非混杂模式下，如果设置网卡为混杂模式需要root权限

linux下设置

1、设置混杂模式：ifconfig eth0 promisc

2、取消混杂模式：ifconfig eth0 -promisc

windos下通过特定的软件实现

通过程序设置网卡为非混杂模式:

struct ifreq 结构体可以保存网卡的所有信息:

struct ifreq { #define IFHWADDRLEN 6 union { char ifrn_name[IFNAMSIZ]; /* if name, e.g. "en0" */ } 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]; /* Just fits the size */ char ifru_newname[IFNAMSIZ]; void __user * ifru_data; struct if_settings ifru_settings; } ifr_ifru; }; #define　　ifr_name　　　　ifr_ifrn.ifrn_name /* interface name */ #define　　ifr_hwaddr 　ifr_ifru.ifru_hwaddr /* MAC address */ #define　　ifr_addr 　 ifr_ifru.ifru_addr /* address */ #define　　ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-p lnk */ #define　　ifr_broadaddr ifr_ifru.ifru_broadaddr /* broadcast address */ #define　　ifr_netmask ifr_ifru.ifru_netmask /* interface net mask */ #define　　ifr_flags 　ifr_ifru.ifru_flags /* flags */ #define　　ifr_metric ifr_ifru.ifru_ivalue /* metric */ #define　　ifr_mtu ifr_ifru.ifru_mtu /* mtu */ #define　　ifr_map ifr_ifru.ifru_map /* device map */ #define　　ifr_slave ifr_ifru.ifru_slave /* slave device */ #define ifr_data ifr_ifru.ifru_data /* for use by interface */ #define　　ifr_ifindex ifr_ifru.ifru_ivalue /* interface index */ #define　　ifr_bandwidth ifr_ifru.ifru_ivalue /* link bandwidth */ #define　　ifr_qlen ifr_ifru.ifru_ivalue /* Queue length */ #define　　ifr_newname ifr_ifru.ifru_newname /* New name */ #define　　ifr_settings ifr_ifru.ifru_settings /* Device/proto settings*/

struct ifreq ethref;