引入ping命令和TTL值.ppt

Ping命令及TTL值介绍 Ping命令概述 Ping程序实际就是发送一个ICMP回显请求报文给目的主机，并等待回显的ICMP应答。然后打印出回显的报文。Ping不通一个地址，并不一定表示这个IP不存在或者没有连接在网络上，因为对方主机可能做了限制，比如安装了防火墙，因此Ping不通并不表示不能使用FTP或者TELNET连接。 Ping的目的 Ping主机的IP地址—检验本地主机的TCPIIP地址配置 ping默认网关IP地址---检验连接本地网络和其他网络的路由器是否可达。 ping远端目的地的IP地址----检验与远端主机的连通性 Ping常用参数介绍 ping [-t] [-a] [-n count] [-l length] [-f] [-i ttl] [-v tos] [-r count] [-s count] [[-j computer-list] | [-k computer-list]] [-w timeout] destination-list -t ping 指定的计算机直到中断。ctrl+c停止 -a 将地址解析为计算机名 -n count 发送 count 指定的 echo 数据包数。默认值为 4 -i ttl 将“生存时间”字段设置为 ttl 指定的值 -l length 发送包含由 length 指定的数据量的 echo 数据 包。默认为 32 字节；最大值是 65,527 ping -a Pinging [04] with 32 bytes of data: Reply from 04: bytes=32 time=69ms TTL=244 Reply from 04: bytes=32 time=78ms TTL=244 Reply from 04: bytes=32 time=78ms TTL=244 Reply from 04: bytes=32 time=77ms TTL=244 Ping statistics for 04: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 69ms, Maximum = 78ms, Average = 75ms ping -t -l 10000 Pinging [6] with 10000 bytes of data: Reply from 6: bytes=10000 time=169ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=187ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Reply from 6: bytes=10000 time=171ms TTL=55 Ping statistics for 6: Packets: Sent = 11, Received = 11, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 169ms, Maximum = 187ms, Average = 172ms Control-C ^C ping -i 3 Pinging [6] with 32 bytes of data: Reply from 3: TTL expired in transit. Reply from 3: TTL expired in transit. Reply from 3: TTL expired in transit. Reply from 3: TTL expire