COMP2330 Data Communications and Networking

Transcription

1 COMP2330 Data Communications and Networking Dr. Chu Xiaowen (Second semester, academic year) Last update : Jan Laboratory 2 IP techniques: ipconfig, ping, tracert and netstat Objectives: 1. Understand IP address (ipconfig) 2. Use ping to test network connectivity, packet loss, and round-trip delay 3. Use tracert to understand IP routing 4. Use netstat to check TCP connections 1. ipconfig ipconfig is a command line tool used to control network connections. It is used to print the current connection details, including IP address, Subnet Mask, Default Gateway, etc. ipconfig /all ipconfig /release ipconfig /renew Display all detailed configuration information. Release the IP address for the specified adapter. Renew the IP address for the specified adapter. For release and renew, if no adapter name is specified, then the IP address leases for all adapters bound to TCP/IP will be released or renewed. Example: ipconfig Result: Exercise 1: Try the following command to get more info from your computer. ipconfig -all

2 2. ping Introduction The name ping is taken from the sonar operation to locate objects. The ping program is used to test whether another host is reachable or not. Ping works by sending ICMP echo equest packets to the target host and listening for ICMP echo response replies. Normally, if you cannot ping a host, you are unable to use telnet or ftp to connect the host. Conversely, if you cannot telnet to a host, ping is often the starting point to determine what the problem is. Ping is also used to measure the round-trip time to the host, which gives us indication of how far away from that host. Example ping Result Exercise 2 : ping to get the IP address of: hk.yahoo.com Check whether they are same or partially different. 3. tracert (on Windows XP) (traceroute / tracepath on Unix) Introduction The tracert lets us see the route from the own machine to the target host, and display the IP datagrams from one host to another. Example 1: tracert Result 1:

3 Analysis: you will be routed out of our Ho Sing Hang Campus ( *.*) to our RRS Campus ( *.*) after pinging the Why? Because the sce(school of Continuing Education) is located in the RRS Campus!. Example 2: tracert Result 2: Analysis: you just need one hop to reach our comp server, because you are in the same sub-network with our comp server. Example 3 tracert Result 3:

4 Analysis: the math dept server needs more hops to reach than our comp server as in example 2, because we are inside our comp dept network. We can consider that we are nearer the comp server than the math dept server But, math dept server needs fewer hops than the SCE server as in example 1, because the dept of math is still in our Ho Sing Hang campus, a big network which covers the subnetworks such as our comp, math, physics, music, etc, but not the RRS Campus. You can see the server name of math dept is euler, a famous mathematician. Exercise 3: Find the web address of Alumni Relations Office (ALRO) of HKBU, by Google. Tell the route from your computer to the ALRO server. Hint: to get the server info, you just need to use the address of xxx.xxx.edu.hk only. DON T use the address of xxx.xxx.edu.hk/yyy/zzz, which indicate a specific file. When talking about route, only server name is useful. 4. netstat netstat (network statistics) is a command-line tool that displays network connections (both incoming and outgoing), routing tables, and a number of network interface statistics. It is available on Unix, Unix-like, and Windows NT-based operating systems. /? : Displays help at the command prompt. (only on Windows) -a : Displays all active TCP connections and the TCP and UDP ports on which the computer is listening. Example 3 netstat Result:

5 Exercise 4: See which TCP/UDP ports are opened in your computer. Hints: you can search by google/wiki netstat for more details. Exercise 5: Tell the IP address of your Subnet Mask and Default Gateway. You can get more details from google or wiki about what are they and what do they do. See [6] Exercise 6: Compare the ping result of and and analyze their differences in IP, respond time, and TTL. Exercise 7: Use tracert to find the trace from your computer to the following address: tracert tracert tracert tracert Look at the results and Try to explain their differe ces. Exercise 8: To display active TCP connections and the process IDs using numerical form (on Microsoft XP and 2003), what command is suitable? Get the answer from the Wikipedia website. Exercise 9: (optional) List all of the active TCP connection and figure out the one which hold the most connections. [Reference] [1] Jan, 2009 [2] Jan, 2009

6 [3] Jan, 2009 [4] Jan, 2009 [5] Jan, 2009 [6] Jan, 2009