DIY Raspberry Pi Wi-Fi Repeater Part 4: IP Forwarding & Access Point

Neural Lantern

In Scene 4 of our Raspberry Pi Wi-Fi Repeater series, we dive into setting up IP forwarding, installing a firewall with iptables, and configuring a Wi-Fi access point. Learn how to forward packets, set up IP masquerading, and debug with tcpdump. Perfect for tech enthusiasts looking to extend their network range! Subscribe for more step-by-step tutorials and check out our website for additional resources. #RaspberryPi #WiFiRepeater #Networking #TechTutorial  New Scene Introduction 00:00:00 Video Editing for Recording Time 00:00:04 Camera Battery Concern 00:00:10 IP Forwarding Setup 00:00:12 IP Forwarding Explanation 00:00:34 Configuration File Access 00:01:24 Editing System Control File 00:01:40 Enabling IP Forwarding 00:02:03 Firewall Installation 00:02:40 IP Tables Installation 00:03:04 IP Masquerading Setup 00:03:33 IP Tables Rules Configuration 00:03:49 Making Firewall Rules Persistent 00:05:03 Access Point Setup Introduction 00:06:11 Network Manager Configuration 00:06:32 Setting SSID and Password 00:07:14 Wireless Security Settings 00:08:24 IP Address Configuration 00:10:17 Verifying Connection Settings 00:11:43 Debugging with TCP Dump 00:12:32 Installing TCP Dump 00:13:39 Monitoring Network Interfaces 00:14:00 SSH Debugging Shortcut 00:15:24 Testing Access Point 00:16:48 Virtual Machine Testing 00:17:02 Call to Subscribe 00:17:44 QR Code and Website Promotion 00:18:21  Thanks for watching!  Find us on other social media here: - https://www.NeuralLantern.com/social  Please help support us!  - Subscribing + Sharing on Social Media - Leaving a comment or suggestion - Subscribing to our Blog - Watching the main "pinned" video of this channel for offers and extras

Transcript

00:00okay we've started a new scene here I just cut the video I edited it a little bit so that we

00:06could so that I could have more recording time before the camera dies the camera is going to

00:11take a poop anyway um so next we need to set up IP forwarding because what's going to really

00:16happen is when you send a request let me see if I can find that image real fast where the heck is

00:22that I'm not it's right here so this is the after image so if you think about it what's going to

00:30happen is uh when your clients send a signal you know to the pi the pi is not the internet the pi

00:38is just connected to your router the pi then needs to forward the data the packets whatever

00:45to its other interface so this is like you know wireless LAN one and this is like wireless LAN

00:52zero if you recall so we need to set up an ability to forward packets between uh interfaces so that

01:00we can get the packets to wireless LAN zero and then they'll eventually end up being sent to the

01:05router so that's the basic idea of what we're doing now and then also uh IP masquerading

01:10so I'm going to close this and then go back to the pi here we just need to uh

01:21edit a command real fast let's see so there's a configuration file called system control

01:28in the etc directory so we can do cat system control dot configuration uh a lot of its stuff

01:36is uh braid out or I guess like not configured by default so if we edit it wait what's going on

01:42there dude what is happening did you see that oh I did pseudo nano pseudo nano that was dumb

01:49so a lot of these options are just they're commented out you know they're not like enabled

01:53so this is a good idea for security purposes but uh we definitely need to forward so

02:00I'm going to uncomment net.ipv4.ip forward equals one to enable ipv4 ip forwarding on ipv4 and then

02:12I'm going to uncomment the next one for ipv6 forwarding even though no word even though we're not setting up

02:18ipv6 in this video uh it'll be a pain in the butt if you start trying to set up ipv6 on your own

02:23later and you forget to come back to this file so that's that's what I'm going to do

02:27so we can immediately apply the changes uh with this command if we want to I'm just going to put

02:34it on the screen real fast but we don't need to because I'm going to do a reboot after we set this up

02:39so the next thing we need is we actually need to install a firewall so that we can

02:44keep persistent firewall rules that will help us ip masquerade at least this is the way I know how to

02:51do it so by default this operating system doesn't actually have ip tables installed the pi is totally

02:57open and unprotected kind of weird but okay so I'm going to go sudo apt install ip tables so I can get

03:04a firewall and then I'm going to install install ip tables persistence actually let's do persistent

03:11later so that we don't have to do any other commands when you install persistent it'll grab

03:17whatever's already in there and just make it persistent so you don't even have to remember

03:20extra commands if you're wondering why we're installing a firewall at this point uh it's not

03:25necessarily to protect the pi although we can use that to protect the pi pretty soon

03:30um or like later but it's really so that we can have masquerading work which is in this case

03:37it's very closely related to forwarding data from the two network adapters so I'm going to go so we

03:43just installed ip tables I'm going to say ip tables list all the rules are empty everything is open the

03:49firewall is really letting everything through so then I'm going to do sudo ip tables network address

03:58if the source is coming from oh yeah if the source is coming from your uh access point

04:08and it's trying to go out to the uh to the ethernet adapter that's wrong that's not going to work for our

04:14purposes eventually we'll say the judgment is that it's okay to masquerade

04:19um we should replace this with wireless land zero also so that they both work

04:27basic idea is if a client of the pi access point is sending information into the pi like it's it's

04:35making a web request then we're saying it's okay to masquerade as that ip address as we send the data

04:42along uh to either the ethernet port or the wireless land port so I put both of those in there

04:48because I want it to work for both uh you may only need to put wireless land zero or whatever your

04:53adapter is for the uh the one that's making the primary connection to the original router

04:58so now let's make the rules permanent with uh iptables save sudo apt install ip tables

05:07oh wait no we don't even necessarily need to use save

05:12if we just install persistent after we did it whoops apt install

05:17persistent because I think it'll ask us if we want to save the rules right now

05:21yeah right okay so I'm going to say yeah so I can save myself some commands

05:27yeah go ahead and save them uh if you installed persistence uh right away you could either uninstall

05:34them and then reinstall them I guess otherwise the command is basically uh this to take whatever

05:39rules are currently inside of iptables and then just send them into that saved rules file

05:45and then you would do the same thing for the v6 if you wanted ipv6 double check what has been saved

05:51with uh this command so we'll say uh sudo cat and then that's the file where the rules are saved

05:59so it's telling me yeah they are saved so if I reboot the pi uh the rules should still be there now

06:05and then we have enough time to set up the access point um we are very very very close

06:13yeah it's probably actually going to work now set up the access point and um

06:20hmm yeah I'll show you how to do a debug uh a debug thing after this I'm not going to do it

06:28so you can see but I'll show you how to do it anyway so let's set up the access point remember

06:32uh we're only connected with one of the radios right now so sudo network manager

06:36command line interface connection show and we're only connected as a client

06:40so now we need to do this sudo network manager command line interface

06:44connection add not device wi-fi connect but connection add

06:48the type is going to be wi-fi

06:50and then we're going to specify the interface name as wireless LAN 1 that's the dongle that we

06:56installed earlier and then we're going to set into access point mode so that's mode ap

07:01and then I'm just going to set the connection name to become access points you can obviously

07:07set this to whatever you want it doesn't really matter and then we have to set the ssid probably

07:13this should be different than your main router because we're not doing like uh wds you know

07:18roaming access points or anything like that this is going to be a totally separate access point

07:22with a totally separate network we're just going to eventually make it work so that we can route

07:27between the two networks seamlessly so that it'll feel like one network but it's technically another

07:32subnet at least so choose something for your ssid that your neighbors won't call the police about

07:38i'm going to do well la de freaking god

07:43and then uh we'll set a password so i'm going to just make up a random password right now in another

07:50window and then uh i can change it later i guess

07:54this thing is not working hello okay i'm just going to copy paste a random password

08:08so i'll set the uh let's see what is it 802

08:1411 wireless security

08:19oh you know what it's probably easier if i just do this

08:26from inside network manager so i added the connection the ssid is well la de freaking dot

08:32uh then i can just kind of show the connections become access point is not up yet so i'm going to

08:38edit it connection edit become access points so now it's i don't know for me it's a little bit

08:46easier to edit all these things so i'm going to do set 802 11 802 11 is kind of like you know the

08:52wireless family of standards dot band oh for the band depending on your dongle uh you might want

09:002.4 gigahertz or 5 gigahertz also depending on your country for me i'm going to try to get this

09:06on 5 gigahertz so that is band a uh i think the other band is either

09:10actually you know what network manager will tell me yeah bg i was going to say just g by itself yeah

09:18so i'm going to do a because i want 5 gigahertz at least for this then i'm going to do set uh

09:23the wireless uh security property of the key management and i'm going to set it to basically

09:31a pass pass key or like a pass phrase some of these settings are probably going to be out of

09:36date by the time you watch this video so you might want to go look up the latest or ask me a million

09:41times to uh provide an updated video i guess although this took like hours and hours and hours just to

09:47even record kind of i'm kind of over it to be honest i hope this works for everybody because

09:53regardless i'm eating an entire pizza by myself when this is finished let's see group let's see

09:59proto group pairwise um so we're just type we're just typing stuff now now psk so that's the uh the

10:07password so then i'm going to paste the random password that i just came up with

10:12and then uh hit enter to get that in there and then we're going to set up the ip address remember

10:17this is another adapter we still need to set its ip address so ipv4 dot addresses

10:23i've got to do set sorry address is 192.168.5.1 which is what we decided on and then uh block 24

10:33yes to manual and then i'm going to set its uh gateway

10:37to nothing oh the gateway has to be empty i made this mistake earlier if you actually set

10:45the gateway to something like you probably want to do 192.168.1.1 if you do that then the access

10:53point will tell all of its clients that the gateway is 1.1 but the problem is they can't actually access

10:591.1 so they'll just be offline so you need to make sure probably that the gateway is empty so we'll do

11:05print ipv4 notice how the gateway is empty dns is empty dns search is empty they all should just be

11:14empty because we want uh the information to come from elsewhere at least on that uh on that so uh you

11:22know we want dns mask to tell them everything if those have values you can basically say remove ipv4

11:29uh dot addresses and then it should work so let's see what else do i have to add addresses gateway dns

11:36dns search and then we'll print it'll to 11 wireless security just to double check it make sure that

11:43you've entered all the right values and then print the ipv4 block again just to double check it and

11:48then hit save uh if you have an error here uh you might want to type fix verify or maybe just go look

11:54at all the settings again but i saved it it seems to have worked so i can now quit

11:59and then uh oh actually maybe i should tell it to start automatically let me just double check

12:06print the connection properties does it say auto connect yes okay so now the access point

12:12should automatically come up whenever uh whenever the pi boots if we're lucky we're incredibly close

12:21right now so i'm gonna do i'm gonna open up another window and i just want you to kind of see

12:26what's what's going on here um or how i was debugging my connection because in the beginning when i was

12:32first learning how to do this i was like where are the packets going is it even trying so for me i made

12:38several windows like this um if your terminal doesn't split windows too bad for you mine is called

12:44terminator you can find it pretty easily it's sudo apt install terminator uh but what i what you

12:51want to do is ssh into the ethernet of the pi three times so i'm gonna do that uh and then oh god

13:00is that why that color code shows up i think i just figured something out uh so you want to do it

13:08three times and then you want to label each window so this window is going to be wireless land zero

13:13uh depending on your terminal you might have to do labeling differently wireless land one and uh

13:21and then i'm going to do ethernet zero on this one so they all we have three terminals one for each

13:28uh interface network interface and i'm basically just going to watch packets on every single interface

13:34so inside of the pi i'm going to first say sudo apt install tcp dump that's a special program that lets

13:41you watch packets as they're traveling all around your your network cards and stuff like that so

13:47sudo apt install tcp dump then the command is sudo tcp dump and then dash i to specify an interface

13:56and then we'll specify ethernet zero here and then uh here we'll specify wireless land zero we'll just

14:06match the windows that's why i labeled the windows and then here we'll do wireless land one

14:12uh and then so what you'll want to do is hit enter on each of these windows and you'll see like a huge

14:18stream of data you want to uh filter the data by something that's useful for you otherwise it'll be

14:25like way too much data even to even understand so for me i filtered it by icmp echo and then what i was

14:31doing is i was basically just pinging servers like i was pinging inside of the pi i was having it ping

14:38itself and then i was having it ping like my router then i was trying to have it ping clients and then

14:43i was having the clients ping the pi and ping the router and then finally start pinging the internet

14:46you're just doing pings all over the place uh in order to try to narrow down what might be wrong with

14:52your uh situation um if you follow this tutorial probably it'll be fine but like for me you know i like

14:58to debug and things were going wrong when i was first learning this so this was super super helpful

15:03i just want you to know um here's a problem though every time you reboot the pi let me do that right

15:09now you do pseudo reboot every time you reboot the pi you lose connection uh connections to all the

15:18other windows so then you have to like log back into the pi and then type out the command all over

15:22again so instead a nice shortcut could be something like this ssh into the pi ssh pi at 192.168.1.123

15:33and then in quotes or single quotes i'm going to do single quotes on the outside and then double

15:40quotes on the inside because you kind of have to use different quotes now what's going to happen is

15:45when i go into the pi it's going to log into the pi and immediately start doing the tcp dump for me

15:51so that means when um when i get booted i just have to i just have to hit the up arrow and i can

15:57immediately go back into the pi and i don't have to type out the commands again let me show you real

16:02fast uh with a slightly different way so i'm going to go ssh pi at 192.168.1.123 and then do a single

16:10quote and instead of doing tcp dump i'm just going to type echo by itself so notice how it logs in

16:17oh i didn't echo anything hello it logs in it prints hello and then it logs out so now

16:25i'm kicked out of the pi let's pretend that we lost internet or network i just hit the up arrow

16:31and hit enter so it's like so fast you don't have to type all those uh all those letters again

16:36so i'm not going to debug here i'll do that in another window if i really need to but i just

16:41wanted you to know and it's fun it's fun to know when things are really starting to work

16:45in the meantime it looks like the pi has probably rebooted now let's try some well we know that the

16:54pi's network works for itself so now the next step is how can we prove that this access point actually

16:59works oh my gosh um i think i'm going to cut the video so that i can show you that it works

17:05by logging into a a virtual machine that's inside of this virtual machine that i'm recording on it's

17:13probably going to be super slow we'll see what happens okay so i'm going to cut the scene right

17:18now when i come back we'll be logging into a virtual machine

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