linux：扩充ARP表

参考：https://www.cyberciti.biz/faq/centos-redhat-debian-linux-neighbor-table-overflow/

vi /etc/sysctl.conf

 ## works best with <= 500 client computers ##
# Force gc to clean-up quickly
net.ipv4.neigh.default.gc_interval = 3600
 
# Set ARP cache entry timeout
net.ipv4.neigh.default.gc_stale_time = 3600
 
# Setup DNS threshold for arp 
net.ipv4.neigh.default.gc_thresh3 = 4096
net.ipv4.neigh.default.gc_thresh2 = 2048
net.ipv4.neigh.default.gc_thresh1 = 1024

sysctl -p