陕西师范大学 计算机网络 实验报告
实验七 ICMP
一、实验目的
1.熟悉并掌握 wireshark的操作。 2．分析ICMP协议。
二、实验器材
1.PC机电脑一台。
2．下载wireshark软件并安装
三、实验内容及问题回答
1. ICMP and Ping
1. 打开wireshark开始抓包
2. 在widows命令下输入ping –n 10 www.ust.hk
3. 待ping程序终止，停止wireshark抓包
－1－
1. What is the IP address of your host? What is the IP address of the destination host?
源和目的IP地址。
我的主机的IP地址为：10.2.136.33 目的主机的IP地址为：202.117.145.153
2. Why is it that an ICMP packet does not have source and destination port Numbers
答：从课本可知，ICMP用于主机和路由器彼此交互网络层信息。ICMP报文有一个类型字段和一个编码字段，用来表示特定的消息被接收。因为它能解释所有消息，所以ICMP到应用层不需要端口号。
3. Examine one of the ping request packets sent by your host. What are the ICMP type and code numbers? What other fields does this ICMP packet have? How many bytes are the checksum, sequence number and identifier fields?
－2－
类型和编码字段
ICMP类型：8（回显请求） ICMP编码：0
ICMP报文其他字段包括：checksum(2字节)、identifier（2字节）、sequence number（2字节）、sequence number (LE)、data fields.
4. Examine the corresponding ping reply packet. What are the ICMP type and code numbers? What other fields does this ICMP packet have? How many bytes are the checksum, sequence number and identifier fields?
类型和编码字段
ICMP类型：0（回显回答） ICMP编码：0
ICMP报文其他字段包括：checksum(2字节)、identifier（2字节）、sequence number（2字节）、sequence number (LE)、data fields.
－3－
2. ICMP and Traceroute
1.打开wireshark开始抓包
2.在widows命令下输入tracert www.inria.fr 3.待tracert程序终止，停止wireshark抓包 截图如下：
－4－
5. What is the IP address of your host? What is the IP address of the target destination host?
答：我的主机IP地址：10.2.136.33
目的地主机IP地址：193.51.193.149
6. If ICMP sent UDP packets instead (as in Unix/Linux), would the IP protocol number still be 01 for the probe packets? If not, what would it be? 答：如果ICMP发送UDP数据报，IP协议号应该为0x11.十进制为17，表明交给UDP。
7. Examine the ICMP echo packet in your screenshot. Is this different from the ICMP ping query packets in the first half of this lab? If yes, how so?
ICMP 请求回显报文
答：ICMP回显数据报与ping 请求数据报有相同的字段。
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