ping 命令

ping 命令

最近，我从cnaaa.com上购买了云服务器，开通了centos系统。

Linux 系统的 ping 命令是常用的网络命令，它通常用来测试与目标主机的连通性，我们经常会说“ping 一下某机器，看是不是开着”、不能打开网页时会说“你先 ping 网关地址 192.168.1.1 试试”。

它通过发送 ICMP ECHO_REQUEST 数据包到网络主机（send ICMP ECHO_REQUEST to network hosts），并显示响应情况，这样我们就可以根据它输出的信息来确定目标主机是否可访问（但这不是绝对的）。

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。

1. 命令格式：

ping [参数] [主机名或 IP 地址]

2. 命令功能：

ping 命令用于：确定网络和各外部主机的状态；跟踪和隔离硬件和软件问题；测试、评估和管理网络。如果主机正在运行并连在网上，它就对回送信号进行响应。每个回送信号请求包含一个网际协议（IP）和 ICMP 头，后面紧跟一个 tim 结构，以及来填写这个信息包的足够的字节。缺省情况是连续发送回送信号请求直到接收到中断信号（Ctrl-C）。

ping 命令每秒发送一个数据报并且为每个接收到的响应打印一行输出。ping 命令计算信号往返时间和（信息）包丢失情况的统计信息，并且在完成之后显示一个简要总结。ping 命令在程序超时或当接收到 SIGINT 信号时结束。Host 参数或者是一个有效的主机名或者是因特网地址。

3. 命令参数：

-d 使用 Socket 的 SO_DEBUG 功能。

-f 极限检测。大量且快速地送网络封包给一台机器，看它的回应。

-n 只输出数值。

-q 不显示任何传送封包的信息，只显示最后的结果。

-r 忽略普通的 Routing Table，直接将数据包送到远端主机上。通常是查看本机的网络接口是否有问题。

-R 记录路由过程。

-v 详细显示指令的执行过程。

-c 数目：在发送指定数目的包后停止。

-i 秒数：设定间隔几秒送一个网络封包给一台机器，预设值是一秒送一次。

-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。

-p 范本样式：设置填满数据包的范本样式。

-s 字节数：指定发送的数据字节数，预设值是 56，加上 8 字节的 ICMP 头，一共是 64ICMP 数据字节。

-t 存活数值：设置存活数值 TTL 的大小。

4. 使用实例：

实例 1：ping 的通的情况

命令：

ping 192.168.120.205

输出：

[root@localhost ~]# 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 2：ping 不通的情况

命令：

ping 192.168.120.202

输出：

[root@localhost ~]# 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 3：ping 网关

命令：

ping -b 192.168.120.1

输出：

[root@localhost ~]# 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 4：ping 指定次数

命令：

ping -c 10 192.168.120.206

输出：

[root@localhost ~]# 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 5：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：

[root@localhost ~]# 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 6：通过域名 ping 公网上的站点

命令：

ping -c 5 www.58.com

输出：

peida-VirtualBox ~ # 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 7：多参数使用

命令：

ping -i 3 -s 1024 -t 255 192.168.120.206

输出：

[root@localhost ~]# 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