20170724

配置内核参数
临时修改内核参数
[root@server ~]# cd /proc/sys/net/ipv4
[root@server ipv4]# cat icmp_echo_ignore_all
0
[root@server ipv4]# echo 1
1
[root@server ipv4]# echo 1 >icmp_echo_ignore_all
[root@server ipv4]# ping 192.168.0.1
PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
永久修改内核参数
#sysctl -a | grep icmp_echo_ignore_all
#vi /etc/sysctl.conf
net.ipv4.icmp_echo_ignore_all=1
#sysctl -p
#sysctl -a | grep icmp_echo_ignore_all

#vi /etc/sysctl.conf
net.ipv4.icmp_echo_ignore_all=1
#ping 192.168.0.1     失败
#sysctl -p