IFSM 430 Lab exercise 4 Name_____________________________________ Scanning and other Internet activities. Use Easyterm Telnet (instead of regular Windows telnet) to login to Linux. Use the ping command to see if a computer exists or is running. For example, use UMUCAD's web site (a machine in Yokota): ping www.ad.umuc.edu Use Ctrl c (holding down the Ctrl key, press the c key) to stop. Notice that the computer's IP address is shown. What is it? Notice the time field of each ping message; this is the round-trip time of each little 64-byte packet. Notice it varies, due to network activity. You can also ping an IP address: ping 202.239.133.11 will ping machine 11 in the lab. ping the machine you are sitting at. What is the round-trip time? ping a non-existent machine: ping asdf.ad.umuc.edu What is the response? Use the traceroute command to see the route on the Internet to some machine or site. A list of the gateways/routers ("hops") that any message goes through is shown, along with the time it takes to get to each hop. For example, traceroute www.ad.umcu.edu How many hops to it? What's the "real" name of that computer? (ping that machine to see its IP address.) The first hop on the list is the router in the lab, sitting next to the Sign-in machine. Do a traceroute to a machine that you know about. Write down its name, IP address and how many hops to it. Use the finger command to see who's logged on to a machine. finger by itself lists the logged-on users of the local machine. To see a remote machine, include a @name argument: finger @anjin.ad.umuc.edu How many users are logged on? Who are they? (It's not a heavily used machine). Many sites don't run a finger server because it's considered to give out too much information. The Linux machine does not run a finger server: finger @202.239.133.19 [or you can do: finger @localhost ] What's the message? (this is what you get from a machine that doesn't have a finger server). Use the netstat command to see what Internet services are available on the local machine: netstat -lt [ -lt option shows listening TCP ports ] What are their names? (smtp is a mail server, pop-3 allows accessing mail from the mail server, auth is an identification protocol, 6000 is the X server). Use nmap to scan ports and services on a machine. nmap localhost will allow you to add port numbers to the list of services netstat gave you. nmap can scan any machine's ports (unless firewalled or otherwise protected). Scan your Windows machine. What ports/services does it have? (nterm, if your machine has it, seems to be MSN messaging) Scan anjin and count how many services it is offering.