arp table cache
1. arp -n 显示arp table
arp -n
Address HWtype HWaddress Flags Mask Iface
9.115.251.1 ether 00:00:0c:07:ac:1b C eth0
2. 删除某个arp表项
arp -d 9.115.251.1
3. 设置某个arp表项
# arp -s 9.115.251.20 00:00:0c:07:ac:cc
# arp -n
Address HWtype HWaddress Flags Mask Iface
9.115.251.1 ether 00:00:0c:07:ac:1b C eth0
9.115.251.20 ether 00:00:0c:07:ac:cc CM eth0
发送arp包, arping
1. 广播谁有某个ip地址
arping 9.115.251.1
2. 指定端口发送
arping -I eth0 9.115.251.1
3. 指定发送次数
arping -c 2 -I eth0 9.115.251.1
抓arp包
好了，我们需要验证一下到底有木有发送arp，收到arp
tcpdump -i eth0 -p arp