CMIT 265 pinging. Name:____________________________ What's your host's NIC's IP address? ___________________________ What's its NIC's MAC (physical) address? ___________________________ Disconnect from any WiFi networks. 'ping' sends an ICMP Echo Request to, and gets ICMP Echo Response from, a computer/node/host. ping is the simplest communication. No data is exchanged. ping is the basic networking troubleshooting tool. You can use it to track down a problem by starting at the computer and moving progressively outward. Note: WiFi is too slow and variable to get good consistent ping times. ping -? to see the list of possible switches/options for ping 1. First question you need to know: Is TCP/IP networking working on the computer? In Command Prompt: ping localhost 'localhost' is always a synonym for self. In the unlikely event that TCP/IP is not installed or running, ping will indicate. Where is the ping reply coming from:________________ (this is a special IP address called the "loopback" device or address that is always associated with the local host.) IPv4 it is 127.0.0.1 IPv6 it is ::1 ping -4 localhost to force IPv4 Where is the ping reply coming from:________________ What is the amount of time each ping takes:_______________ Unfortuneately, Windows ping is in milliseconds only. What are the Min, Max, and Average times:____________________________ Ping the IPv4 loopback address. Any difference in the ping times:________ Ping the NIC's IP address. Any difference in the ping times:________ Anything sent to localhost or the loopback device never leaves the computer. Pinging the localhost works even if not connected to the network. Unplug the RJ-45 connector from the NIC jack and then ping the localhost. Anything different:________________ (Pinging the disconnected IP address still works???_______) Reconnect. Ping your computer's IP address. Any difference in the ping times:________ localhost, loopback address and host's own IP address are all the same computer/NIC. Second question you need to ask yourself as you track down a networking or connectivity problem: 2. Can the computer communicate with another computer on the LAN with TCP/IP? Ping your neighbor's computer by its IP address (ask your neighbor what his/her IP address is): ___________________ If your neighbor's computer doesn't respond (personal firewall can be set to not respond to incoming pings), then ping your instructor's computer. (Wait for second "Request timed out." before terminating ping command because often the first ping fails.) What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ Roughly how many times faster is pinging the localhost than pinging your neighbor:___________ Ping the Linux system running in a virtual machine on your instructor's computer. Its IP address is the one with no name in the DHCP clients list. What are the Min, Max, and Average times:____________________________ If you can't ping hosts in the network the problem might be: --bad cable somewhere (your patch cable or horizontal cabling or your neighbor's patch cable or horizontal cabling or a patch cable in the wiring closet), --cable is unplugged somewhere (check the NIC's Link LED), or wall plates, or switch (either input or output port) --you don't have correct IP address, --switch port misconfigured (e.g. wrong VLAN or MAC-based port security), --firewall at destination not responding to the ping. lame-o Windows 7 Firewall allow ping: Firewall | Inbound | New Rule | All Programs | ICMPv4 | Any IP Windows 8/10 Firewall allow ping: Control Panel | Windows Firewall | Advanced settings | Inbound | New Rule | ... Rule Type: Custom | Protocols & Ports | Protocol Type: ICMPv4 | ... ICMP Settings Customize | Specific ICMP types Echo Request. | Next Next Next... Name it maybe "ping request" FIX YOUR FIREWALL if your computer does not respond to pings. What is the IP address of the Default Gateway for this network:______________ Ping the default gateway by its IP address. What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ How does pinging the default gateway compare with pinging your neighbor,timewise:_______________ The default gateway is in the same network as your neighbor. Differences in ping times among hosts in the same network might be due to network congestion or congestion at the host or just a slow responding host. ***************************** SKIP ***************************************** ping the switch at 192.168.100.199 The switch has been configured to be a host in our network. What is the amount of time each ping takes:_______________ ****************************** END SKIP ************************************* ***************************** SKIP ***************************************** Ping your instructor's computer wireless by its IP address 192.168.100.x (where x is TBD). What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ It's on the same network but the wireless segment will typically be slower and more variable than the wired part. ****************************** END SKIP ************************************* IP addresses starting with 192.168. are special "unregistered" addresses for private internal networks not directly accessible from the Internet. These computers are "hidden" from the Internet by the router/default gateway which does a translation to and from the 192.168 address to an Internet-accessible "registered" IP address (this process is called NAT: network address translation). Notice that all the IP addresses in our network start with 192.168.200. because that is the network portion of these IP addresses, the last octet (8 bits) being the host portion. Third question in the progressive movement outward from localhost, to LAN, to internetwork. 3. Can the computer communicate with another computer on a different network (LAN) in the same organization? What is the IP address of the "farside" of the default gateway (its address in the adjoining network that it is connected to) 192.168.0.0 This has to be determined by logging into the default router and finding out its farside address. Instructor will show. ________________________________ Ping the farside of our default gateway. Average ping time:________________________________ Usually the same amount of time as pinging the nearside as it is the same device. The default gateway of the adjoining 192.168.0.0 network is 192.168.0.1 (.1 is often the address of the default gateway of a network) Average ping time:________________________ All communication outside a LAN goes through the default gateway (a router). Those pings first went from your computer to the default gateway in a frame with your computer's MAC as the source and the default gateway's MAC as the destination. That was their first step, or "hop". From the default gateway the pings were sent into the internetwork, possibly making many hops (each hop is a router) before arriving at the IP destination. The replies came back to the default gateway from the internetwork and then were put in a frame with its MAC as the source and your MAC as the destination (the default gateway might have first had to do an ARP broadcast to find out your MAC). ping uses IP address as destination, even for a destination in the LAN. You can't ping by MAC address, not even for a MAC in the LAN. What error message do you get when you ping your localhost by its MAC address: _________________________________________________________ Use the -l option of ping to specify the size in bytes of the dummy data that ping sends out in its message. ping the same host in our network that you pinged before but include 50000 bytes (50KB) as the data size. What is the average ping time for it now:_____________ The default data size is 32B. *********************** SKIP ************************************************** Two networks over is the 192.168.12.0 network. Its default gateway is 192.168.12.1 Average ping time of it:________________________ That network has a printer in it: 192.168.12.5, ping times:________________ There seems to be hosts at 192.168.13.* (which actually is the same as the 192.168.12 network, via supernetting), so try pinging .96 or .112 or .201 in that network; the ping times are very variable, indicating those might be WiFi clients. ______________________________________________ That 192.168.12.1 router connects to the 153.254.222.0 network whose default gateway seems to be 153.254.222.1 This is probably our ISP's network, offbase. (or is it in our wiring closet???) Average ping time:________________________ That device connects to 220.150.2.146, so ping it:_____________________ That one connects to 219.99.88.90, so ping it:____________ By the gap in ping time, this might be off-island. ********************* END SKIP ************************************************** (This part could be done on your home WiFi.) Finally, do we have connectivity to the Internet: 4. Can the computer communicate with some computer on the Internet? ping 87.248.98.7 This is an IP address that has been assigned to some organization. What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ Run: ping -? to see the list of possible switches/options for ping and find the one that will translate/resolve an IP address into its hostname (what is the switch:____) and rerun the above command to find the hostname of the host at that IP address:______________________________ Use the same switch to find the name of the 216.58.210.4:_______________ BTW, What's a long time to ping? ping can ping by IP address or by DNS hostname. ping www.cenpac.net.nr (if that doesn't work, try: dns1.cenpac.net.nr ) (If your ping is IPv6, put a -4 option in the command line.) nr is the country code for Nauru, an island nation out in the Pacific, What are the Min, Max, and Average times:____________________________ It's using a satellite microwave link, which are slow because of the uplink and downlink to the satellite. ping www.anadyr.ru OR .org This is/was? in Siberia. Update: no longer in Siberia :( What are the Min, Max, and Average times:____________________________ These above two are about as far away as you can get in the Internet these days, a whole second or so away for the roundtrip. UPDATE: both are faster now than they used to be. :) and :( Some addresses don't respond to the ping request: ping www.asia.umgc.edu (which exists, and has an IP address) What is the result:_________________________ A DNS name is first translated to its IP address: a lookup request is sent to the DNS server to "resolve" the DNS name to its underlying real name, i.e. its IP address. Some addresses don't exist, so a ping request isn't sent: ping arfarf.asia.umgc.edu What is the result:__________________________ A DNS lookup was attempted, it failed to find that name, so the pings weren't sent (there was no IP address to send them to). *********************** SKIP ************************************************** IP address(es) of DNS server(s):______________________ _________________________ ping -a of our DNS server. What is its name:______________________ OR use 8.8.8.8 as DNS server. Ping the DNS server(s) to see if it/they are responding. What is the average ping time for it:_____________ What is the average ping time for the other:_____________ ********************* END SKIP ************************************************** *********************** SKIP ************************************************** Find out the IP address of a computer's networked printers by XP: Start | Settings | Printers and Faxes | Properties of [whatever make/model] | Ports | Standard TCP/IP port 7/8 : Start | Devices and Printers | rt click Printer | Printer properties | Ports | Standard TCP/IP port of a computer in the lab. widen the Port column to see IP_ which is the IP address:________________ Ping it from our network (i.e. your computer). What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ Some printers are very sluggish to respond to pings. ********************* END SKIP **************************************************