Networking for Ethical Hackers - Building A Basic Network with Cisco Packet Tracer (Re-Up)

Key Takeaways

so now we're going to use a tool called packet tracer and what we're gonna do is we're going to set up a very simple network using some Cisco command line just so you can kind of get a feel for everything we've done thus far so let's go ahead I've got Google open over here all I want to do is just type in packet tracer so we're looking for is the net a CAD download here the first link and you're going to need to enroll to download packet tracer so you'll have to sign up it's free once you sign up you will get some free courses through Cisco which is pretty cool but you'll also be able to download packet tracer so go ahead and do the signup and once you sign up you'll be provided a link to download packet tracer download it install it with default everything and then go ahead and open it up so once you got it opened go ahead and I would suggest pausing the video once you got all set up and come back unpause the video and we'll move on okay so moving on I'm gonna go ahead an open packet tracer on my end okay so when we look at packet tracer you can see down here that we have our devices so here's our network devices we've got n devices components wiring or connections and what we can do is if we're sitting in network devices the first thing it gives us is routers then it has switches hubs wireless devices so pretty much everything we've talked about here security so those will be your firewalls and then they've got Wynn emulation so what we can do here is we can pick a specific router if we wanted to but we can just go ahead and just use generic so I'll just grab this first generic one right here and we'll drag this guy out and this is gonna act as if it's our home router so every router needs what this is layer 3 so every router is also going to need some switching right if we're gonna put some devices on it so what we can do is just grab a generic switch here and we'll put this in right here and lastly what I want to do is I want to take some end devices and we'll take a laptop put that in here and maybe we have a computer as well so the nice thing that we have is when you double click on these say this laptop you can configure it with how you wanted to get some settings right so one of the settings that we're going to do today is we're going to setup DHCP remember DHCP is where we assign addresses through the router automatically or we could set a static IP address here and use that to talk but what's the fun in that we're gonna set up DHAP and see how it works so there's that we also have this desktop feature here where you can get into a command prompt very nice to do some setup here so acts almost as if it's a Windows machine and if you take a look here let's just say we do an IP config we have all zeros right now because we have no IP address so we'll go ahead and get that set up here in a second so if we're thinking about this as a home network we got to think okay well the switch is running on a MAC addresses right so we don't need to assign anything there per se but what we need to do is we need to assign something maybe here so let's come into the router first we need to do some things on the router we need to configure if we click on CLI over here we need to configure a few different things we need to give it an IP address and we need to set up DHCP so we're in this router here and you see that it just has this little greater than symbol so we're just in a basic mode right now what we're going to need to do is type in en which stands for enable you can hit tab or you can just type in en here and it'll work as well so now you got this little pound sign or the hash tag and this tells you you're in your terminal right here so there's different types of configuration modes and we're going they have different names but we're not gonna get into that because you don't need to know and memorize all this but from here we can do a bunch of different show commands so one show command we can type is show IP interface and you don't have to type this out you can tab it again you don't have to type the full word show IP interface brief I'm just showing you that you can also I could just say show IP interface brief like this it'll also work so you can write shorthand when you're using Cisco command-line so if we look at this IP interface brief we see that we have some fast ethernet ports we've got two of them here we've got some serial ports and then we've actually got some more fast ethernet ports down here so what we can do is take one of these fast ethernet ports assign it an IP address where you see it says assigned or unassigned here and then we'll take it online you can see it's administrative lead on right now let's down down so we're gonna have to bring that online so let's do that first so what we need to do is we need to get into configuration mode which is configure terminal you could also just type in compte conf space t that'll work okay so now we're in the configuration so we need to select an interface that we want to modify and this interface we're going to modify is this fast ethernet 0/0 so we'll say interface FA you can hit tab see that it types out fastethernet 0/0 okay now you see that we're in this interface and all we have to do here is assign it an IP address we say IP address let's just give it 192 168 0.1 and we have to give it a subnet mask too so we'll give it a whack 24 address hit enter okay and the last command we need to do is we need to turn this port on and I can show you what that looks like before we do it so if you try to do if you try to see your interface brief here right now it'll tell you you can't so you say show IP interface brief they'll say it's undetected because you're not supposed to be running these show commands when you're doing configurations well we could type a command in that says do so we'll say do show IP interface brief and it'll tell us so now you can see that I have an IP address here for this fastethernet 0/0 but we're still administrative lead áown so to bring down a port you would type shutdown to bring up a port you would actually just type in no shutdown or no shut so we hit enter there you can see the status has changed to up okay hit enter there we could type an exit this will bring us back type an exit one more time okay and we could type in WR to write our changes just type in it's right so WR sensor right so now our changes are saved so what we can do here now is we could connect the switch and the router but it's still not going to give out an IP address they could talk in theory we can set statics now and we can talk up here but unless we set up DHCP it's not going to work so let's go ahead and set up DHCP now I'm going to admit that this is a little advanced this is a little out of scope but I kind of want you to see the process of DHCP and just kind of see what it's doing for you we a lot of times just have everything done for us and we take it for granted but when you have a Cisco background a little bit you get to see everything done by hand so let's go ahead and do that we'll get back into the configuration terminal and we're going to say service DHCP and then we have to give DHCP a pool so we'll just name it we'll call it Maine and this is where we can get into our configuration once we've named the pool so let's go ahead and define what our network is gonna be well our network is gonna be one eye two dot one six eight one zero and we'll do 2 5 5 s across the board and this is where subnetting becomes important so if we only wanted a few hosts maybe we would change this from a whack 24 to a Lac 30 for example so we'll just give it a basic standard whack 24 hit enter we're gonna have to define the default router so what's our router gonna be well this is our router and we assigned the IP address at 0.1 I notice that I made a typo here so what I'll do is I'll go back so if we give this 0.1 and I will say no network 192.168.1.0 and we can tap up again I apologize I made the other one zero so we'll call this 0.0 okay so we have network 191 6 8 0.0 we have our default router set and let's go ahead and set the DNS server while we're at it we can just call that also 1 9 2 168 0.1 can be our router can be doing DNS as well and we could type in exit and then something we can do here as well we can exclude an IP address from DHCP so let's I P DHCP will say excluded address and we will say we want to exclude 1 2 1 6 8 0.1 we don't want to assign this because this is our router ok so now we have this configured we can type in exit we can type in wr4 right save our changes here and now we're ready to start attaching some interfaces so what we can do is we can take this magic little cable over here and it'll pick out the cable type for you so you just click on that and you touch it there touch it there it'll start linking over here and you can do the same for your laptop to your switch and from your PC to your switch okay so we've got green lights but we've got orange lights in here so we're not talking over looks like fast ethernet you could see that we're up and it says fast ethernet but we're not actually getting an IP address yet so let's turn these guys green as well if we look in here let's type in remember that we set a no static IP we just have it blank so our IP is nothing what we can do is we can hit DHCP and DHCP here and this should start generating so let's go into I don't know why it's in there okay let's try this let's try IP config again okay and it's giving us this apipa address so let's see what we've done wrong so if we go into here let's do something called a show run we're gonna look at our configuration and see if I made a typo somewhere okay so here's our IP dhcp excluded address we've got our IP dhcp pull so we've got the default router we've got the DNS server and we've got the network range here let's hit space space again okay we've got the IP address here it's up and if we keep looking through here I think everything looks fine so let me go ahead and what I'll do is I'll bring that up and down one more time so we'll say the internet fast ethernet 0/0 or interface fastethernet 0/0 we'll say shut I'll bring it down no shut bring it back up and that should take a second here okay and now let's come back up so let's type in our router here and see if we have any bindings IP dhcp bindings but we're still in configure a LAN exit see this works and it likes it one more time okay well sometimes this does not work depending on the configuration here so this simulates an iOS command-line interface but it doesn't always have the right the right commands here so let's go back let's go to this PC let's see now that works there okay it picked it up now we can see that generated and we don't have any ipv6 so let's close that one and now it's generated here too so let's go back and see the command prompt one more time it looks like it taking it down might have done it some some times if it's not working you do a shut know shut sometimes it's finicky so this is good experience for you to see me struggle a little bit even setting these up and I have experience setting these up so you could see here this address type this 169 is actually called apipa and what that is it's like a local address if you're getting DHCP but you're not able to talk out so this is a 169 address identifies that but now you can see we are talking out and we're getting a 192 168 0.2 with the Gateway here of 0.1 and then 2 v 5s across the board ok and then if we come over here let's see what IP address it gave us and this gave us 0.3 so there's a lot more configuration we can do we can go into the router we can set DHCP lease times we could say you know I want this to be good for a day or be good for an hour etc but this is just the basic common gist of what your home router typically does typically your home router is doing the switching for you and it's doing DHCP for you as well as wireless capability so it's almost like a three-in-one but when you break it down by layer you have your layer two you go up to your layer three because this does no routing here this only works on MAC addresses on the switch so switch is saying hey I can move packets in between here or I should say frames these are frames so it can move frames in between these computers based on MAC address but the IP packets are done by the router and the router would go out if we were to continue on here so this is the edge of our network is what we'd call this and if you were to have another router you could say this is the edge of your ISPs Network and they would connect to each other and they would talk based on these settings that your ISP gives this router so your ISP might say hey let me tell you what the public address for this router is gonna be and it's gonna be 72 1335 70 right and it'll give you that IP address and your router this router can actually be doing DHT perfect for this router because you're not paying for a static if you're paying for a static you're paying a lot of money and usually that's only businesses that do that so they're doing some sort of DHCP as well where if you don't check in you'll lose your IP address too so their routing here and if you're configuring a router on this side you need to configure some sort of routing protocol likely here this is running on BGP and you can have internal routing and external routing and that's way out of scope here but it's just something to think about when you think about you know the little cloud sometimes they put over for your ISP well your ISP has a router that's sitting on the edge as well and you're talking to them via that router so it is routed a router goes down to a switch and then talks down into laptops or your computer your cell phone whatever you want your devices to be so that's really it for this lesson all I wanted to do was show you a basic basic network setup I didn't want you to necessarily learn a ton of cisco command line but i wanted you to see some basic commands you saw show IP interface brief that's one of the biggest commands you can look at because they'll tell you the interfaces that you have whether they're up or down what IP addresses are assigned to them etc show run is the other show command that is good to have in your arsenal because you saw we used it I wanted to make sure I didn't make a typo which I didn't so that kind of fixed my troubleshooting a little bit and I ended up just going and taking the port down and bringing it back up so those are two very very good commands to know another one is using enable and then configure terminal to get into the configuration terminal and setting an IP address is a very basic Cisco test one level so some of these are some of these are pretty low level and then some of them that I showed you like the assigning a DHCP I don't think you'll see that unless you're taking your CCNA the second part of your CCNA exam so a little out of scope but it applies some of the concepts that we've learned so you saw DHCP in action you saw me assigned a DNS server and we got to talk more and more about the OSI layers so using all this information now you should be pretty comfortable with common network protocols how ipv4 and ipv6 differ what a MAC address is and somewhat of the OSI model you know at least layers one through four hopefully all the layers now and you should be pretty comfortable with subnetting so that's it for this lesson I appreciate you taking the time and building a network with me and if you liked the video please do subscribe please share with a friend and please keep watching thank you so much [Music] [Music] you