hey everyone welcome back to another video here on tryhackme today we're going to be taking a look at the room what is networking begin learning the fundamentals of computer networking in this bite size and interactive module this is a really cool module this is uh i believe had some new technology introduced into it by our developers very excited to go through this and it should be a nice one let's go ahead and dive into task one what is networking networks are simply things connected for example your friendship circle you are all connected because of similar interests hobbies skills and uh different sorts of things and this is sort of where the term networking comes from if you are doing job hunting or other things like that as you know someone who knows someone things like that networks can be found in all walks of life a city's public transportation system the london tube is a great example of this because it is a very well and interconnected network and it's a very big one too infrastructure such as the national power grid for electricity another very important network meeting and greeting your neighbors again it's not a more of a safety network in that case the postal system for sending letters and parcels and so on and so forth you can see networks everywhere in your life and they're very very important concepts but more specifically in computing networking is the same idea just dispersed to technological devices take your phone as an example the reason that you have it is to access things because if it didn't do anything it'd be kind of like an old uh i don't know an old palm pilot or an old pda where you know it's not that much good it can it may be a calculator disputing the claim that your teacher would say that you wouldn't have a calculator carried around in your pocket all the time but you can see the importance of networks we'll cover how these devices communicate with each other in the rules that follow in computing a network can be formed by anywhere from two devices to billions so it doesn't really matter as long as it's more than or two or more these devices include everything from your laptop and phone to security cameras traffic lights and even farming networks are integrated into our everyday life be it gathering data for the weather delivering electricity to homes or even determining who has the right way at a road right of way rather because networks are so embedded in the modern day networking is an essential concept to grasp in cyber security take the diagram below as an example alice bob and jim have formed their note or their own network we'll come on to this a bit later we'll talk about this a little bit later on so you can see just a basic network networks come in all shapes and sizes which is something that will also come on to discuss throughout this module let's go ahead and dive into the question what is the key term for devices that are connected together that is a network and there we go we'll go ahead and close that and let's go ahead and go into task two what is the internet now that we've learned what a network is and how one is defined in computing just devices that are connected let's explore the internet the internet is one gigantic network that consists of many many small networks within itself using our example from the previous task let's now imagine that alice made some new friends named zayn and toby that she wants to introduce to bob and jim this is starting to sound like an office reference the problem is that alice is the only person who speaks the same language as zayn and toby so alice will have to be the messenger and you can see that alice is here in the middle where she's the messenger for these two because alice can speak both languages they can communicate to one another through alice forming a new network the first iteration of the internet was within the arpanet project in the late 1960s this project was funded by the united states department of defense or defense department and was the first documented network in action however it wasn't until 1909 when the internet as we know it was invented by tom or tim berners-lee by the creation of the world wide web or otherwise shortened to www it wasn't until this point that the internet was used as a repository for storing and sharing information like it is today let's relate alice's network of friends to computing devices the internet looks like a much larger version of this diagram and you can see this is a very abbreviated intensely abbreviated version of the internet where we have many small networks that are interconnected with a translating device in the form of a router even though this is not necessarily translating it's nat and pat don't worry about that right now just know that this is just a way that we have gateways for our private networks to talk to the internet as previously stated the internet is made up of many small networks all joined together these small networks are called private networks so think your home network a business network things like that where networks connecting these small networks are called public networks try saying that 10 times fast or the internet so to recap a network can be one of two types a private network or a public network devices will use a set of labels to identify themselves on a network which we will come onto in the task below so who invented the worldwide web that will be tim i'm gonna have to grab his name from up here because i can't spell it tim berners-lee and we can just copy that and there we go if i don't leave the other part of the answer on there all right perfect let's move into task three identifying devices on a network to communicate and maintain order devices must be both identifying and identifiable on a network what use is it if you don't know whom you're talking to at the end of the day you know if just yelling into the void and the void starts talking back that's a little strange devices on a network are very similar to humans in the fact that we have two ways of being identified via our name and our fingerprints among a couple other things but those are good generalizations now we have can change our name through deed uh poll but however uh we can't change our fingerprints so we can change your name we can't change our fingerprints that's the general gist of this every human has a an identical set or individual set of fingerprints which means that even if they change their name there is still an identity behind it the general idea behind this is that yes you can change the what you're called and that's something that you know you might have a nickname or other things like that but you're always going to have some permanently identifiable marks and computers have the same thing devices have the same thing they have an ip address which can change but they have a what's in theory a globally unique mac address or a media access control address you can see that right there think of it it's kind of similar to a serial number but these are all standardized and it's split up in a couple of different ways where the first half is the manufacturer and the second part is the unique part i won't go too far into this but just know that well you can be called different things your mac address is generally in theory globally unique ip addresses briefly an ip address or internet protocol address can be used as a way of identifying a host on a network for a period of time where that ip address can then be associated with another device without the ip address changing first let's split up precisely what an ip address is in the diagram below so before we go into this think of this as your street address other people can live there you probably aren't the only person that's lived at that address and you might not be the only person you know using that computer at that address uh and this can change hands and it might change over time with you know people changing the way that the address system is set up for streets things like that but this is how we know how to send mail to you and the same thing goes for computers an ip address is a set of numbers that are divided into four octets and you can see one here one here one here and then one here and you can see that these have a range of zero to two hundred and fifty-five uh this is because they're made up of eight binary bits if i remember correctly and uh they the range for that is zero with all the bits being turned off and then if you turn the model once or everything is on your limit is 255. the value of each octet will summarize to be the ip address of the device on the network so all of these put together the individual octets can mean things but generally speaking don't worry about that right now this is your straight address on the network it's how your computer knows to talk to someone else so this might be your router's address on your home network uh this actual network itself is pretty common for home networks so 192. 168.
1. and this last bit would be what changes or sometimes this is a zero but these first two pretty common for home networks and that's where you have the first and second octet or octets that are static i won't go too far into that but just know that this might be a router address it's very common for that uh what's important to understand here is that the ip addresses can change from device to device but they cannot be active simultaneously more than once so if you have a street address your neighbor can't have the same one you can swap houses with your neighbor and that'd be a little weird but you could you will have a different address living at that house you can't have that collision because that causes problems and both of the devices will say hold on we need to figure something out here ip addresses follow a set of standards known as protocols these protocols are the backbone of networking and force many devices to communicate in the same language which is something that we'll come on to another time however we should recall that devices can be on both a private and public network depending on where they where they are will determine the type of ip address they have a public or private ip address so real quick there was a note in here protocols so the reason that we have that and the reason that we all use the same language metaphorically speaking to talk to each other over the internet is because when the internet first came out we had a bunch of different protocols and sort of like trying to talk to a bunch of different people that don't speak the same language doesn't really work out you can kind of get the general gist but you know the the communication just doesn't happen so we established these protocols um and they were something that were much more uh solidified with the creation of wi-fi uh definitely something that if you're interested in learning a little bit more the wikipedia page has a great summary of why this is important but generally speaking we have to have rules otherwise a lot of device manufacturers like microsoft and hp ibm you go on name whatever one you want they'll just make their own and claim it's the fastest and the other devices won't work with it because they want you to buy their device so just keep that in mind that is why we have protocols that force everyone to use the same standardized communication a public address is used to identify the device on the internet whereas a private address is used to identify a device amongst other devices i think of this home network versus anyone can talk to it on the internet generally speaking take the table a and screenshot below as an example here we have two devices on a private network and we can see the private ranges right here there are three private ranges predominantly uh 192. 168 and these last two bits can change our last two octets rather can change is a major one uh the 10 zero zero zero is another big one and there's another one that i can never remember the fall of it uh because it has a range in the second octet um i recommend taking a look at these and we might go over them later in the room but just know that there are three very distinct ranges that the private ip1s can fall into and these would be public because they don't fall into that range and we can see them labeled over here on the side uh these will be on the same network because these are well okay in theory they could be on the same network they might not necessarily but they're very likely to be because we have 192 168 1 and then 74 and then 77.
these could exist on the same network because they don't conflict um and they could talk to each other in theory if there's not routing rules or other restrictions in play uh and here you can see this would might be a screenshot from a router that we have these two devices with their mac addresses don't worry too much about this right now just know that this is in theory unique and these are the private ip addresses that they have on the network and they were assigned via dhcp which just means that i have a pool of addresses first come first serve and we give them out and they're not necessarily like you get this one permanently on this network that would be a static addressing these two devices will be able to use their private ip addresses to communicate with each other however any data sent to the internet from either of these devices will be identified by the same public ip address so your home would have a public ip address in this case but you'll have your private ip your private network sits behind that public ip addresses are given by your internet service provider or isp for short uh at your monthly bill so when you buy when you have an internet service contract set up you'll have a nip address that is associated with your home uh sometimes this can be associated with a couple different homes this can get a little weird you can pay to have this not change and be static but just know that this is something that exists on the public internet in this case as more and more devices become connected it is becoming increasingly harder to get a public address that isn't already in use uh for example cisco an industry giant in the world of networking estimated that there will be approximately 50 billion devices connected on the internet by the end of the uh 2021. so the current year in the time of this recording enter ip address uh or address versions so far we've only discussed one version of the internet protocol addressing scheme known as ipv4 ipv4 is pretty old it had some limitations that we didn't really anticipate this many devices to be connected to the internet uh but we have smart homes and other things like that which dramatically increases uh the number of devices that we're connecting to the internet on the whole especially if they need public addresses and this uses a numbering system uh of two raised to the 32nd ip addresses so 4. 92 or 29 billion so you can see where there's a shortage because we have more devices that are connected to the public internet than we have available for ipv4 addresses ipv6 is a relatively new iteration of the internet protocol addressing scheme to help tackle this issue although it is seemingly more daunting it boasts a few benefits so it supports up to two to the 128th power of ip addresses so this is 340 trillion plus uh in theory we should ever run out of these we'll see what happens uh just because more devices are being connected um and it resolves that big issue with ipv4 because we were going to run out now we really can't more efficient due to more or new methodologies so there's a bunch of new technologies that were introduced in this don't worry too much about knowing this just know that in general ipv6 has a bunch of cool new shiny features and you can see there's a comparison of those two addresses so with an ipv4 we had these four octets and this is a lot longer i won't go too much in the detail just know that ipv6 exists this is not as common to see on home networks generally speaking you need to know about this just that it exists and once you get further into penetration testing or defense knowing that ipv6 is another way that things can talk to each other that's just another thing to be aware of so that's all you need to know at this point in time just focus on ipv6 and this is going to be where most everybody focuses nowaday anyhow let's go ahead and talk about mac addresses devices on a network will all have a physical network interface which is a micro trip board found on the device's motherboard this is your ethernet port or your wi-fi card whatever this is this network interface is assigned a unique address at the factory it was built at called a mac address a media access control address this is referred to as burnt in uh in quotation marks uh this is because in theory can't be changed you can do spoofing and other things with this don't worry about that too much right now just know again this is in theory globally unique and the odds that you're gonna have two devices on the same network that have the same mac very very very very infinitesimally small chance big businesses can run into this every once in a while but it's pretty rare the mac address is a 16 character hexadecimal number a base 16 numbering system used in computing to represent numbers you can see that this is hex b16 where it rolls over from nine and it starts a b c d e and then f is the last one and you can see that this is an example of a mac address here where it is six groups of two of these the first six characters represent the company that made it so right here that made the networking interface and the last six is in theory a unique number so and you can see that broken apart down here however an interesting thing with mac addresses is that they can be faked or spoofed as i mentioned before this spoofing occurs when a network device pretends to identify as another by using its mac address when this happens it can often break poorly implemented security designs that assume devices talking on a network are trustworthy because they're not don't worry too much about this this is more of a situation of just know about this it's not something too major and you'll come across it later on in your security career take the following example a firewall is configured to allow any communication going to and from the mac address of the administrator if the device were to pretend or spoof this mac address this firewall would now think that it is receiving communication from the administrator when it is not so places such as cafes coffee shops and hotels alike often use mac address control when using their guest or public wi-fi this configuration could offer better services i.
e a faster connection for a price if you're willing to pay the fee per device uh the interactive lab attached to this task has been made to replicate this scenario and let's go ahead and spin that up right now so in theory you could just pretend to be someone else that is something that happens let's go ahead and scroll back down to the practical bit the interactive labs simulate a hotel wi-fi network we have to pay for the service you'll notice that the router is not allowing bob's traffic bob being right down here but alice's package green right here are going through just fine because she paid for the wi-fi try changing bob's mac address to the same as alice's and see what happens and let's see i think i need to scroll down and let's try changing these to be the same if i can type this all out let's see if i can just highlight this copy oh i can and there we go and now suddenly we can talk out to the internet and we got a flag uh don't worry too much if you can't read that i'm going to go ahead and paste that here so thm you got on try hack me so in theory you could spoof your back address if you haven't paid for wi-fi like this just something to know about again just know the idea that mac address control exists and that mac addresses are in theory globally unique that's really all you need to get from this let's go ahead and go into the other questions what does the term ip stand for that is going to be internet protocol what is each section of an ip address called that is going to be an octet how many sections in digits does an ip address have that will be four and let's see what does the term mac stand for media address control i believe uh it should be access control i'm guessing there we go perfect let's go to move into task 4 ping with icmp let's go and pull this up so we don't have to watch back it's fly across ping is one of the most fundamental network tools available to us ping uses icmp internet control message protocol packets to determine the performance of a connection between devices for example if the connection exists or is reliable so this is a way that we can determine performance the time taken for icmp packets traveling between devices is measured by ping as such as in the screenshot below we can see the output of a ping command here this measuring is done using icmp's echo packet and then icmp is echo reply from the target device and you can see that we have a ping command with our target up here and then we have our time here and then it looks like we have our average back here so the average performance or how much time it takes us to talk to another device pings can be performed against devices on a network such as your home network or research resources such as websites this tool can be easily used incomes installed on operating systems os's such as linux and windows the syntax to do a simple ping is ping and then the ip address right here or your website url so ping is the command and then either the website url or the ip address and you can see that demonstrated down here here we are pinging a device that has the private address of 192. 168. 1.
254 ping informs us that we have sent six icmp packets all of which were received with an average time of 5.
