‫Some routers and firewalls are configured to not pass ICMP Echo requests or Echo reply requests.
‫Attackers sometimes try to map out remote networks by pinging all the possible addresses and collecting
‫replies.
‫So blocking this type of traffic at the perimeter is fairly common.
‫Just because you do not receive a reply to a ping does not necessarily mean that the host is not available.
‫Trace Route is a computer network diagnostic tool for displaying the route or path of packets through
‫the internet between your computer and a specified destination computer.
‫It also measures the amount of time each hop took.
‫When you run the utility, it initiates the sending of a packet, including in the packet at TTL a time
‫to live value, which is also known as a hop limit.
‫As the packet passes through a router, the title is decrement it until when the title reaches zero.
‫The packet is destroyed and an ICMP time exceeded message is returned.
‫Trace route works by setting the total for a packet to one, sending it towards the requested destination
‫host and listening for the reply.
‫When the initiation machine receives a time exceeded response, it examines a packet to determine where
‫the packet came from.
‫So this identifies the machine.
‫One hop away, then the tracing machine generates a new packet with detail to.
‫And uses that response to determine the machine to hops away and so on.
‫The command trace route is available on many modern operating systems.
‫On Unix like systems such as free BSD, Mac, OS and Linux, it's available as a command line tool.
‫On Unix like systems, Trace Root sends by default a sequence of UDP packets, trace root is also graphically
‫accessible in Mac OS within the network utility suite.
‫And Microsoft Windows.
‫It's named traceroute.
‫And Windows traceroute sends ICMP Echo request instead of UDP packets.
‫For IPV six, the tools sometimes has a name trace route six or TRACEROUTE six.
‫Let's look how the Trace Route Command operates in our host machine and virtual machines as well.
‫So I'm on my host machine, this is Mac OS, and I'll open a terminal screen command space to open the
‫Spotlight Search Bar and type terminal.
‫Start the terminal app, and now I'm on a terminal screen.
‫Trace route is the command I'll use.
‫So if you run out with no parameter, you get a brief help about the usage of the command.
‫So now let's run the command with a target host.
‫We timed out in the first hop.
‫And in the second one as well, where it happens.
‫No worries.
‫And yes, here are the other halves.
‫This is the path at the back.
‫It's follow from my host machine to the target web server.
‫In Mac OS, you can also trace the packets with a graphical UI, which I mentioned before.
‫So go to the network utility tool, press command and spacebar once more to open spotlight and type
‫network utility and find it and open it.
‫There's a trace root tab in the network utility window.
‫Just type the target host and click the Trace button.
‫Let's see how it all works in Cali.
‫So now I'm in Cali and I have a terminal screen, open type trace round and hit enter.
‫So you'll see the help for this particular command, and it's a bit more detail than the one in Mac
‫OS.
‫So now I want to show you the network configuration of my colleague.
‫Go to college settings, click network adapter, and as you see, we run college in that mode where
‫the host machine Mac provides network address resolution.
‫We'll talk about that soon for all network traffic, and Carly shares the IP address of the host.
‫Now I want to test the network connection first, so I'll ping the Google DNS 8.8.8.8.
‫And right, that's no problem at all.
‫You can use control C Keys to end the Pinkman.
‫You know, not just don't use control L.
‫OK, now I'll run the trace route with the target hosting column.
‫The first hop is a gateway prepared by VMware for my virtual machines.
‫And as you can see, all the other hops are blocked.
‫We cannot trace packets from the VMM in that mode.
‫So let's have a look at the trace, our command options once more.
‫Here there's an option uppercase T, which sends TCP syn packets.
‫Now I'd like to try the command once more with this option.
‫OK, so we have the first and the last hope this time.
‫So now I want to show you the command in a Windows system.
‫Here is my up to date Windows eight system.
‫It has an IP.
‫Check the connection.
‫Ping.
‫And yes, the network is running good.
‫Just where we want it.
‫Let's look at the network details first from the network and sharing center, click Ethernet zero and
‫then the details button.
‫And here are the details.
‫Default Gateway is ninety nine point two, DHP is nine nine two five four.
‫As you know, these are the devices prepared by VMware for our NAT network.
‫So now I go to the settings of the VMware Fusion Inn network adapter.
‫We confirm that the VM is in that network mode.
‫Now I'm in the command prompt.
‫As I mentioned, the command is traceroute in Microsoft systems.
‫So right down the target, host and press enter.
‫So the first hop is, again, the Gateway.
‫And just like in Cali, since this VM is also in that mode, the requests for other hops are timed out.
‫So while the command is running, I'd like to show you the command help.
‫So just type tracer out and hit enter.
‫So we didn't enter the host this time, and here is a usage of the tracer command.
‫Trace completed, and there is no result given as expected, because we're in that mode.
‫I know you knew that, but I just wanted to make sure.
‫So now I'm going to run my Windows VM in bridge mode and try the command once more.
‫And once again, click the hardware settings icon on the menu bar, VMware Fusion and select network
‫adapter.
‫So I'm using Wi-Fi to connect to the internet right now, so I choose Wi-Fi under the bridge networking
‫section.
‫Now, this is the IP address assigned by the DHC Heat and subnet mask of the Network.
‫Again is set by DHP.
‫So will see how the DHP works.
‫Just stay with me here, so as you see in the network and sharing center window, the active network
‫disappeared as soon as I changed the network adapter of the VM.
‫And a second.
‫The new network is activated, click Ethernet zero and look at that the details button, so click on
‫that to see the network settings and those are the new ones.
‫So now we're in the one nine two two one six eight one two Dot X IP block.
‫And we have a different DHCP and gateway run by the network admins of my office building.
‫So let's go back to the command prompt and trace the route of the packets once more.
‫So first, I want to check the network as I always do, so I'll ping the Google DNS and yes, we have
‫the internet connection.
‫I mean, now, is it time to trace the route?
‫The first request is timed out.
‫Remember the results of my host machine, right?
‫The second request timed out as well.
‫And here are the other hops, we now have the results.