ping命令
ping命令用来测试主机之间网络的连通性。执行ping指令会使用ICMP传输协议，发出要求回应的信息，若远端主机的网络功能没有问题，就会回应该信息，因而得知该主机运作正常。
有些服务器为了防止通过ping探测到，通过防火墙设置了禁止ping或者在内核参数中禁止ping，这样就不能通过ping确定该主机是否还处于开启状态。
linux下的ping和windows下的ping稍有区别,linux下ping不会自动终止,需要按ctrl+c终止或者用参数-c指定要求完成的回应次数。
语法
ping(选项)(参数) || ping [参数] [主机名或IP地址]
选项
-d：使用Socket的SO_DEBUG功能；
-c<完成次数>：设置完成要求回应的次数；
-f：极限检测；
-i<间隔秒数>：指定收发信息的间隔时间；
-I<网络界面>：使用指定的网络界面送出数据包；
-l<前置载入>：设置在送出要求信息之前，先行发出的数据包；
-n：只输出数值；
-p<范本样式>：设置填满数据包的范本样式；
-q：不显示指令执行过程，开头和结尾的相关信息除外；
-r：忽略普通的Routing Table，直接将数据包送到远端主机上；
-R：记录路由过程；
-s<数据包大小>：设置数据包的大小；
-t<存活数值>：设置存活数值TTL的大小；
-v：详细显示指令的执行过程。
参数
目的主机：指定发送ICMP报文的目的主机。
常用范例
实例一：ping的通的情况
命令：
ping 192.168.120.205
输出：
# ping 192.168.120.205 PING 192.168.120.205 (192.168.120.205) 56(84) bytes of data. 64 bytes from 192.168.120.205: icmp_seq=1 ttl=64 time=0.720 ms 64 bytes from 192.168.120.205: icmp_seq=2 ttl=64 time=0.181 ms 64 bytes from 192.168.120.205: icmp_seq=3 ttl=64 time=0.191 ms 64 bytes from 192.168.120.205: icmp_seq=4 ttl=64 time=0.188 ms 64 bytes from 192.168.120.205: icmp_seq=5 ttl=64 time=0.189 ms --- 192.168.120.205 ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4000ms rtt min/avg/max/mdev = 0.181/0.293/0.720/0.214 ms [root@localhost ~] #
说明：
实例二：ping不通的情况
命令：
ping 192.168.120.202
输出：
#
ping 192.168.120.202
PING 192.168.120.202 (192.168.120.202) 56(84) bytes of data.
From 192.168.120.204 icmp_seq=1 Destination Host Unreachable
From 192.168.120.204 icmp_seq=2 Destination Host Unreachable
From 192.168.120.204 icmp_seq=3 Destination Host Unreachable
From 192.168.120.204 icmp_seq=4 Destination Host Unreachable
From 192.168.120.204 icmp_seq=5 Destination Host Unreachable
From 192.168.120.204 icmp_seq=6 Destination Host Unreachable
--- 192.168.120.202 ping statistics ---
8 packets transmitted, 0 received, +6 errors, 100% packet loss, time 7005ms
, pipe 4
[root@localhost ~]
#
说明：
实例三：ping网关
命令：
ping -b 192.168.120.1
输出：
#
route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
[root@localhost ~]
#
ping -b 192.168.120.1
PING 192.168.120.1 (192.168.120.1) 56(84) bytes of data.
64 bytes from 192.168.120.1: icmp_seq=1 ttl=255 time=2.02 ms
64 bytes from 192.168.120.1: icmp_seq=2 ttl=255 time=1.83 ms
64 bytes from 192.168.120.1: icmp_seq=3 ttl=255 time=1.68 ms
64 bytes from 192.168.120.1: icmp_seq=4 ttl=255 time=1.98 ms
64 bytes from 192.168.120.1: icmp_seq=5 ttl=255 time=1.88 ms
--- 192.168.120.1 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4000ms
rtt min/avg/max/mdev = 1.682/1.880/2.020/0.129 ms
说明：
实例四：ping指定次数
命令：
ping -c 10 192.168.120.206
输出：
#
ping -c 10 192.168.120.206
PING 192.168.120.206 (192.168.120.206) 56(84) bytes of data.
64 bytes from 192.168.120.206: icmp_seq=1 ttl=64 time=1.25 ms
64 bytes from 192.168.120.206: icmp_seq=2 ttl=64 time=0.260 ms
64 bytes from 192.168.120.206: icmp_seq=3 ttl=64 time=0.242 ms
64 bytes from 192.168.120.206: icmp_seq=4 ttl=64 time=0.271 ms
64 bytes from 192.168.120.206: icmp_seq=5 ttl=64 time=0.274 ms
64 bytes from 192.168.120.206: icmp_seq=6 ttl=64 time=0.295 ms
64 bytes from 192.168.120.206: icmp_seq=7 ttl=64 time=0.269 ms
64 bytes from 192.168.120.206: icmp_seq=8 ttl=64 time=0.270 ms
64 bytes from 192.168.120.206: icmp_seq=9 ttl=64 time=0.253 ms
64 bytes from 192.168.120.206: icmp_seq=10 ttl=64 time=0.289 ms
--- 192.168.120.206 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9000ms
rtt min/avg/max/mdev = 0.242/0.367/1.251/0.295 ms
[root@localhost ~]
#
说明：
实例五：时间间隔和次数限制的ping
命令：
ping -c 10 -i 0.5 192.168.120.206
输出：
#
ping -c 10 -i 0.5 192.168.120.206
PING 192.168.120.206 (192.168.120.206) 56(84) bytes of data.
64 bytes from 192.168.120.206: icmp_seq=1 ttl=64 time=1.24 ms
64 bytes from 192.168.120.206: icmp_seq=2 ttl=64 time=0.235 ms
64 bytes from 192.168.120.206: icmp_seq=3 ttl=64 time=0.244 ms
64 bytes from 192.168.120.206: icmp_seq=4 ttl=64 time=0.300 ms
64 bytes from 192.168.120.206: icmp_seq=5 ttl=64 time=0.255 ms
64 bytes from 192.168.120.206: icmp_seq=6 ttl=64 time=0.264 ms
64 bytes from 192.168.120.206: icmp_seq=7 ttl=64 time=0.263 ms
64 bytes from 192.168.120.206: icmp_seq=8 ttl=64 time=0.331 ms
64 bytes from 192.168.120.206: icmp_seq=9 ttl=64 time=0.247 ms
64 bytes from 192.168.120.206: icmp_seq=10 ttl=64 time=0.244 ms
--- 192.168.120.206 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 4499ms
rtt min/avg/max/mdev = 0.235/0.362/1.241/0.294 ms
[root@localhost ~]
#
ping -c 10 -i 0.01 192.168.120.206
PING 192.168.120.206 (192.168.120.206) 56(84) bytes of data.
64 bytes from 192.168.120.206: icmp_seq=1 ttl=64 time=0.244 ms
64 bytes from 192.168.120.206: icmp_seq=2 ttl=64 time=0.195 ms
64 bytes from 192.168.120.206: icmp_seq=3 ttl=64 time=0.219 ms
64 bytes from 192.168.120.206: icmp_seq=4 ttl=64 time=0.204 ms
64 bytes from 192.168.120.206: icmp_seq=5 ttl=64 time=3.56 ms
64 bytes from 192.168.120.206: icmp_seq=6 ttl=64 time=1.93 ms
64 bytes from 192.168.120.206: icmp_seq=7 ttl=64 time=0.193 ms
64 bytes from 192.168.120.206: icmp_seq=8 ttl=64 time=0.193 ms
64 bytes from 192.168.120.206: icmp_seq=9 ttl=64 time=0.202 ms
64 bytes from 192.168.120.206: icmp_seq=10 ttl=64 time=0.211 ms
--- 192.168.120.206 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 90ms
rtt min/avg/max/mdev = 0.193/0.716/3.564/1.080 ms
[root@localhost ~]
#
说明：
实例六：通过域名ping公网上的站点
命令：
ping -c 5 www.58.com
输出：
#
ping -c 5 www.58.com
PING www.58.com (211.151.111.30) 56(84) bytes of data.
64 bytes from 211.151.111.30: icmp_req=1 ttl=49 time=14.7 ms
64 bytes from 211.151.111.30: icmp_req=2 ttl=49 time=16.4 ms
64 bytes from 211.151.111.30: icmp_req=3 ttl=49 time=15.2 ms
64 bytes from 211.151.111.30: icmp_req=4 ttl=49 time=14.6 ms
64 bytes from 211.151.111.30: icmp_req=5 ttl=49 time=19.9 ms
--- www.58.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 20101ms
rtt min/avg/max/mdev = 14.618/16.192/19.917/1.965 ms
peida-VirtualBox ~
#
说明：
实例七：多参数使用
命令：
ping -i 3 -s 1024 -t 255 192.168.120.206
输出：
#
ping -i 3 -s 1024 -t 255 192.168.120.206
PING 192.168.120.206 (192.168.120.206) 1024(1052) bytes of data.
1032 bytes from 192.168.120.206: icmp_seq=1 ttl=64 time=1.99 ms
1032 bytes from 192.168.120.206: icmp_seq=2 ttl=64 time=0.694 ms
1032 bytes from 192.168.120.206: icmp_seq=3 ttl=64 time=0.300 ms
1032 bytes from 192.168.120.206: icmp_seq=4 ttl=64 time=0.481 ms
1032 bytes from 192.168.120.206: icmp_seq=5 ttl=64 time=0.415 ms
1032 bytes from 192.168.120.206: icmp_seq=6 ttl=64 time=0.600 ms
1032 bytes from 192.168.120.206: icmp_seq=7 ttl=64 time=0.411 ms
1032 bytes from 192.168.120.206: icmp_seq=8 ttl=64 time=0.281 ms
1032 bytes from 192.168.120.206: icmp_seq=9 ttl=64 time=0.318 ms
1032 bytes from 192.168.120.206: icmp_seq=10 ttl=64 time=0.362 ms
1032 bytes from 192.168.120.206: icmp_seq=11 ttl=64 time=0.408 ms
1032 bytes from 192.168.120.206: icmp_seq=12 ttl=64 time=0.445 ms
1032 bytes from 192.168.120.206: icmp_seq=13 ttl=64 time=0.397 ms
1032 bytes from 192.168.120.206: icmp_seq=14 ttl=64 time=0.406 ms
1032 bytes from 192.168.120.206: icmp_seq=15 ttl=64 time=0.458 ms
--- 192.168.120.206 ping statistics ---
15 packets transmitted, 15 received, 0% packet loss, time 41999ms
rtt min/avg/max/mdev = 0.281/0.531/1.993/0.404 ms
[root@localhost ~]
#
说明：
-i 3 发送周期为 3秒 -s 设置发送包的大小为1024 -t 设置TTL值为 255
