cmn14
Posts: 8
Joined: Fri Sep 29, 2017 4:25 pm

set up local wifi with NO access to internet

Thu Nov 28, 2019 1:53 am

The school has a bunch of wifi networks. I have 25 GoPiGo3s (using Raspbian for Robots). Kids access them via a unique IP via VNC with their own computer (Chromebooks or PCs). The only thing that is important is to get each kid to access his GoPiGo3 (actually accessing the Rpi3B).

No need for access to internet. The school is hesitant to let me use their networks (security, passwords, all kinds of restrictions -- basically they are afraid that he kids will use the networks to watch porn, etc. I need for each GoPiG3/Pi to have a unique IP

All I want is to provide a wifi that would be classroom local -- no connection to anything else.

Is this easy? possible? If I'm independent of the school's network then they won't have a problem.

Thx for any thoughts.

C

dustnbone
Posts: 81
Joined: Tue Nov 05, 2019 2:49 am

Re: set up local wifi with NO access to internet

Thu Nov 28, 2019 3:13 am

https://www.raspberrypi.org/documentati ... s-point.md

Just stop before "Add routing and masquerade" and you should be good to go.

cmn14
Posts: 8
Joined: Fri Sep 29, 2017 4:25 pm

Re: set up local wifi with NO access to internet

Thu Nov 28, 2019 5:12 am

That's wonderful. I had no idea that the Pis could do all that. Can't wait to give it a shot. I really liked the way that the DexterOS had each GoPiGo3 generate it's own wifi signal. However my 40 min class wasted about 10 minutes getting the %^$#* Chromebooks to connect with the bot's wifi. Better with the PCs. Neither had any problem connecting to the schools wifi. The tech guys are still thinking that they like pumpkin rather than raspberry -- especially at Thanksgiving ime. Fought hard against me getting the foundation to buy 25 of the GoPiGo3s.

Common statement "Gee Dr. Noble, I would have done the program but I had trouble connecting". Having a good excuse is better than actually building a program and getting it to work. Too hard -- and really, why worry, daddy will hire someone to do all that for me.

Sign of our times.

Thx again for the help.

C

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MikeDB
Posts: 154
Joined: Sun Oct 12, 2014 8:27 am

Re: set up local wifi with NO access to internet

Thu Nov 28, 2019 12:45 pm

dustnbone wrote:
Thu Nov 28, 2019 3:13 am
https://www.raspberrypi.org/documentati ... s-point.md

Just stop before "Add routing and masquerade" and you should be good to go.
Which is just after it fails for me with a Pi4. All I get is the error message "Failed to start Advanced IEEE802.11 AP" which I haven't been able to fix yet.

So good luck - hope it works for you.

cmn14
Posts: 8
Joined: Fri Sep 29, 2017 4:25 pm

Re: set up local wifi with NO access to internet

Thu Nov 28, 2019 2:00 pm

OK Thx. I'm running way past my headlights with this, and I won't get at it today, anyway.

Have a great Thanksgiving. My oldest son & family are hosting a nice dinner & get together. Very lucky.

Best,

C

cmn14
Posts: 8
Joined: Fri Sep 29, 2017 4:25 pm

Re: set up local wifi with NO access to internet

Thu Nov 28, 2019 6:08 pm

Update: I found an old Linksys WRT54GL v1.1 (2.4Ghz G) router in my closet. Just plugged it in and it generates a wifi signal named linksys. Selected that in my iMac and could easily run the GoPiGo3 with R4R. No internet connection -- which is what I want.

Wonder how many users this could support? Probably makes sense to have each bot/Pi have a static address.

Is it really this simple?

C

dustnbone
Posts: 81
Joined: Tue Nov 05, 2019 2:49 am

Re: set up local wifi with NO access to internet

Thu Nov 28, 2019 7:50 pm

Yeah pretty much :) You might want to edit a few settings on the Linksys to stop it from assigning DNS and Gateway (just to avoid confusing the clients into thinking it's an Internet gateway). You might also want to name the AP something more interesting than "Linksys"

Those Linksys routers can actually do alot more if you install 3rd party firmware on them, I keep one around just for that. But for your purposes, the stock firmware should be fine to handle dozens of simultaneous client connections. The only real limit is the bandwidth of the WiFi radio but it doesn't sound like that's going to be a problem for you.

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MikeDB
Posts: 154
Joined: Sun Oct 12, 2014 8:27 am

Re: set up local wifi with NO access to internet

Thu Nov 28, 2019 8:38 pm

cmn14 wrote:
Thu Nov 28, 2019 6:08 pm
Update: I found an old Linksys WRT54GL v1.1 (2.4Ghz G) router in my closet. Just plugged it in and it generates a wifi signal named linksys. Selected that in my iMac and could easily run the GoPiGo3 with R4R. No internet connection -- which is what I want.

Wonder how many users this could support? Probably makes sense to have each bot/Pi have a static address.

Is it really this simple?

C
Oh I thought you were trying to use the Pi as a WAP. Using the Linksys is far easier. You may find it is configured to only offer 20 IP addresses as is, but I think the range can be extended.

cmn14
Posts: 8
Joined: Fri Sep 29, 2017 4:25 pm

Re: set up local wifi with NO access to internet

Fri Nov 29, 2019 4:46 pm

Thx. My problem is that I have only superficial knowledge about networks in general. I tell my students to learn and really understand (at least) one level below where you are implementing. I'm really a 2-level-below guy, the first level solid, but at least anecdotal about he level below that. I give myself a D when it comes to networking for level 1.

Need to go back to "grade-school" level.

Suppose I set up a pi with a static address, say, 192.168.1.10. (My Linksys router is 192.168.1.1.
Now, what if I go to a network where the router is 10.12.116.1. (at school). I turn on the pi and a another computer, say, a PC and VNC to 192.168.1.10 what will happen? I would bet at least 25 cents that my PC would NOT connect. But I have no idea why or if I should get aggressive and bet 50 cents.

I can solve Maxwell's equations for a variety of situations, but I don't think that will help!

Again, thx for all of the help.

C

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MikeDB
Posts: 154
Joined: Sun Oct 12, 2014 8:27 am

Re: set up local wifi with NO access to internet

Sat Nov 30, 2019 11:30 am

I thought 10.12.116.1 was usually the router admin address - not the sort of thing that should be available to all and sundry :P
But maybe it's different on your system. But how do you stop your more advanced students setting the IP of their Pis to what is I assume a well known (any Android phone will tell them it) address ?

cmn14
Posts: 8
Joined: Fri Sep 29, 2017 4:25 pm

Re: set up local wifi with NO access to internet

Sat Nov 30, 2019 3:37 pm

Advanced students? I'm sure that they can (will?) do that. Gotta remember that in public school systems (at least ours) The mode is to just make sure that you check ALL of the boxes. If that really doesn't do the job, then --well, that's for another day and someone else to add some boxes to check. The distance between setting up regulations and any results is pretty long (and getting longer). Mum's the word.

So, I figure if I can get my 20 to 25 GoPiGo's all working with a network that does not connect to the internet, and doesn't load up the school's, then I avoid having to deal with their technical troops. (Last year when I brought up the idea of buying a bunch of GoPiGo3's that were run by raspberry pi's, they looked at me in wonder -- I almost said, "I assume you all prefer pumpkin", but decided not to -- pretty mature, right!)

Actually, it's all working out well. Just have to watch out using too many multisyllabic words. (sorry!)

Best,

C

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