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traceroute, trace the network traffic.

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So in this lesson, we are actually going

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to learn and try to understand how we

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could troubleshoot the network issues if

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we are having any network issue in our

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environment. And one of the commands

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that is mostly used to see where your

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traffic is going, which gateway or which

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DNS server, it's going from one to

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another to the third, and finally, how

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is it going to reach its destination.

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And to view that entire tracing of

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those network traffic, you have to use a

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command traceroute. And this is a

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command I believe it is also available

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in other operating systems as well. In

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Windows I believe it's called tracert.

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I'm not sure exactly what is the

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command in Mac or other operating

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system. Anyway, we our focus is Linux.

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So let's see what traceroute does. The

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traceroute command is used in Linux to

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map the journey that a packet of

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information undertakes from its source

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to its destination. One use of

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traceroute is to locate when data loss

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occurs throughout a network, which would

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signify a node that's

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down. So as it says, if you just need to

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find the tracing from source to

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destination, how the packet went through

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from one to another. Because each hop in

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the record reflects a new server or

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router between the originating PC and

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intended target, reviewing the results

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of traceroute scan also lets you

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identify slow points that may

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adversely, that may adversely affect your

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network traffic. So it could be many

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different PCs, or many different

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machines or gateways in the middle while

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your traffic is flowing, that affect

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your traffic flow. And that's how

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once you know, hey, I know this is the

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machine that is the troubled machine

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that is causing my network traffic to

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fail, you can find that out if why by

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running the command traceroute. Now,

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the command itself is just simple traceroute,

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and the destination hostname or

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the IP address or the URL in this case.

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So if you are trying to go to a URL, let's say

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google.com, hotmail.com, facebook.com, or

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wherever you are going, or if you are in

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your local environment in your corporate

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world, you probably have an IP or a

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hostname of your machine, then you could

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run traceroute space, the hostname as

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long as your machine or where

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you are running the traceroute can

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resolve that hostname to IP. If it

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cannot then make sure you put in the IP

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address. Okay, let's get into my Linux

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machine. And then we will try this

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traceroute command on it and see how it works.

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So I will go into

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my console. And

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first thing, I want to make sure I am

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online. So I could just do ping any

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website. So you'll see I'm getting a

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response back. So I am online, so now

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let's run the command traceroute. Now,

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when you run it, you have to specify the

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hostname if you are in your environment,

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in a corporate environment, and you are

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running your infrastructure and you

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probably have a lot of servers, you will

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have to specify the hostname if it can

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resolve it, otherwise the IP address.

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But for us, since we are using the lab

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environment, we'll just do google.com

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and hit enter. And you will see the

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first hop it is going to do is, it is going

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to jump on to our modem. This is my

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modem which is also a gateway to my

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traffic. So the first hop it is doing is

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going to my modem. And this is the time

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it takes to go there. And it didn't

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cause any issue. If there was any

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hang time there, it will tell you this

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is going to take that much long time to

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go to the second hop. Second hop is

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going to another gateway right here,

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which is most likely my NAT IP which is

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the internet IP address or the internet,

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IP, the gateway IP and then it will tell

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you it did 1,2, all the way through

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to 14 hops to get to this IP address

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which is the result IP address of

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google.com. So this is how you could

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actually use the traceroute utility to

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find out how your traffic flows from

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your source to the destination. The

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reason it went to my gate at first is

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because that's how my gateway is

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defined. And to find out your gateway,

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you can run the command netstat -rnv,

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and you will see the gateway I have

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for all my traffic should flow from the

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gateway 192.168.1.1. It might be

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different in your environment, depending

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on which environment you're working on.

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And whether you are doing this lesson

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through your work, then you will have a

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different one. If you are doing from home

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then most likely you will have the same

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IP address as your gateway. So this is

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about the traceroute. Try to find it,

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how you could troubleshoot, many times

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people also ask what are the different

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ways you could troubleshoot networking

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related issue in the operating system.

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So you could also bring up this

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traceroute command and this is one of

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the main command that will help you

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troubleshoot network related issues.

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