 So we're trying to find some information very basic information about our our LAN interfaces and To find that information Two commands you can use I have well first ETH tool followed by the interface Pipe into less Tells us a lot of information about our think of the hardware and the link What data rates are supported by your? wired LAN interface What data rates are supported? Well, it says there are different linked modes supported and we see these strange names But you may be able to guess 10 base T half 10 base T full 100 1000 10 100 1000 are the data rates That ethernet support our device So the hardware can send it either 10 megabits per second 100 megabits per second or 1000 megabits per second The base to base T is just the the the name given to the the type of cable or the connector here half and full refer to duplex Half duplex or full duplex half duplex you can send in both directions But one at a time full duplex is typical today where we can send in both directions At the same time. So this is what supported because when you buy the device It supports the old 10 megabits per second The the less old 100 megabits per second and the current typical device or the speed for your devices That is one gigabit per second and The way that works is that your device? Advertises those capabilities to the other end point of the cable The device at the other end point they do some negotiation So auto and negotiation means they they will automatically try and choose the best one Based upon what both end point support Because if the partner only supports 10 and 100 and you support 10 100 or 1000 you cannot use 1000 You use the best with both support. Well, it turns out both of them support 1000 base T full we support 1000 base T full we advertise that to the other side and the other side the partner Advertise that as well. So that's what we use. That's the best one How do we know what we used? The speed tells us 1000 megabits per second and duplex is full try not to resize your windows Duplex is full speed is a current data rate So that the two main fields we care about here at this stage the other one which wasn't the question there the very last line It's very useful when we do some real testing Is the link detected? Yes, what if we look at ETH one? Link detected no, we don't have a cable plugged in and there's nothing at the other end point so This will become useful because sometimes we'll plug a cable into the wrong interface Or we don't plug in the other end point. So a quick check is the link detected. Yes, or no So that's useful when we are setting up the the links IF config tells us our Hardware address and the hardware address. Where does that come from? It's the MAC address. That's the other name or a physical address. Where did it come from? The manufacturer so the company that made the the chip on the motherboard or the PCI slot Assigned this hardware address to it. It should be fixed and unique This is the IP address In my case 10 10 16 201. This is assigned to your computer So this may change whereas you can think the hardware address is fixed It's for the device This is assigned to my computer Where did that come from? Who gave it to me? How did your computer give this IP address? Well, there are three basic ways Either I set it when I start my computer. I Manually set the IP address. I did not do that. I think when you boot your computer you didn't type in the IP address That would be very inconvenient, but we can manually set it We could have a file on our on our system that says when the computer boots load this IP address a static address and The third approach which is more commonly used is that when our computer boots it asks a special server Can you give me an IP address? What protocol does it use to ask a special server for an IP address? D We need to configure our hosts dynamically Dynamic host configuration protocol DHCP is the protocol that My computer asked a server give me an IP address and the server says here use this one We will see that in a later lab DHCP It also gives me this other information and you know your experts about brook broadcast address network masks and From that also you can work out the network address which is 10 10 16 dot zero in this case The way to work it out Look at the internet address Grab the first 22 bits Y 22 255 is 8 bits 8 ones So there's 16 ones 252 is in binary six ones and two zeros So we have 8 plus 8 plus 6 grab the first 22 bits of this binary address Set the last 10 bits to zero and you get 10 dot 10 dot 16 dot zero So that's how you get the network address This is your IPv6 address We're not using that in the in the lab in this course IP version 6 But it most operating systems give an IPv6 address to your computer But in this case it can only be used on the local LAN. It only has a scope of the link It can't be used out on the internet The rest are some statistics or status information about How many packets have been received how many bytes have been transmitted since we started the interface usually since we've booted the computer So we can get a few stats plus the other information about the addresses Let's stay with those tools and a couple of others briefly ETH tool also gives us some stats minus S ETH tool minus uppercase S gives us some statistics Not much different from IF config. So sometimes with when we're running our network We want to diagnose if something's gone wrong Maybe look at how many packets have been sent or how many errors have we got? We shouldn't see many errors If we do we see thousands of errors, then maybe there's some problem with the hardware Or the cable So ETH tool has many options. In fact, we can see statistics with uppercase S a Little bit out of the scope, but we can also change parameters using ETH tool. I don't think we'll do it Very often, but we can use ETH tool to set a value From our ETH zero interface I can set the speed to be 100 megabits per second and the duplex to be full So mine was set at 1,000 megabits per second duplex full if I want to change the speed maybe for testing purposes I want to slow down. I can set it to a specific value When we run it it says operation not permitted Because many networking things we can view the information, but we're not allowed to as the normal user Change the the network settings So what do we do? we do this as super user and I've set up these computers so that the student user is allowed to run most networking commands and if we check now We notice the speed is one 100 megabits per second We should set both speed and duplex together because they go together the speed and duplex mode You get an error if you try to just set the speed and ETH tool has many other options. I'm going to set mine back to 1,000 so to see Statistics we've got ETH tool. We've got IF config plus the other configuration information Before we have a break another way to see the statistics There's a command called netstat Network status and it has many options netstat it produces lots of different output Depending upon the option we specify to see statistics minus s lowercase s here So the options don't always mean the same thing across different commands in ETH tool and then set in netstat it means statistics in If we wanted to get statistics in ETH tool is uppercase s. So that's a bit confusing Try netstat minus s gives us some network status information in particular some statistics I'll pipe it into less because there's a lot of output and Here are a lot more details of all the IP packets of sent any with errors or different types of packets ICMP is used for ping so all the ping messages being received and sent the different types of ICMP messages TCP and UDP are transport protocols. So it shows some statistics about TCP and UDP the connections opened segments received errors so if you Finding diagnosing problems looking for statistics about the error messages received can be useful sometimes and some extensions of UDP and TCP some further statistics for for extensions So some of that we may not know what they they mean, but if you want to find detailed statistics netstat minus s