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Networking but no internet

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Networking but no internet

Postby ef37a » Tue Nov 12, 2019 10:25 am

I have a W7 laptop and two W7 desktop computers. The desktops are networked via copper and the lappy uses wi-fi of course.
Sometime in early 2020 I want the 3 machines off the internet. I shall buy a modest W10 laptop for that duty.

My question is, can I leave all these PCs networked so as to swap files and share a printer but not have internet on them please?

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Re: Networking but no internet

Postby Hugh Robjohns » Tue Nov 12, 2019 10:30 am

Yes. There are several ways of doing it.

The simplest is probably to pick up a second hand modem/router (if you don't have one lying around) which you can set up as a DHCP server and wifi hub for your closed network, and you just don't give that device access or a connection to the interweb.

You would then need a second (your current) modem/router connected to your broadband for your internet access.

This way you'd end up with two wifi networks, one for your live internet access, and one for your closed internal network. Your new W10 laptop would be able to log into either, of course.

With a more sophisticated modem/router you can have a single combined network and setup restrictions on which I addresses can see the interweb and which can't... but that's really beyond my safe knowledge zone so I'll leave it to others to discuss that option.

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Re: Networking but no internet

Postby Eddy Deegan » Tue Nov 12, 2019 10:52 am

If you don't want to involve additional hardware and are willing to spend a few minutes manually configuring the machines you want to keep off the internet, you could leave them connected to your existing router.

In the DHCP settings for your router (I don't know what model you have, but most allow this) you can probably restrict the range of IP addresses it gives out. For example on mine it looks like this:

Image

My router has the internal IP address 192.168.0.1. Note that I've set the starting address to 192.168.0.10, which means that I am free to manually use the IP addresses from 192.168.0.2 to 192.168.0.9 on anything I want in the knowledge that they will not have an IP address conflict with any addresses automatically allocated by the router.

If your router has that ability, set it up in a similar fashion then manually configure the TCP/IP properties on the machines you do not want to have Internet access such that they each have a different IP address in the range that DHCP will not conflict with (for example on my network that could be 192.168.0.2, 3 and 4).

After making this change to your router configuration, or if you encounter IP conflict errors while performing the manual configuration described below, you may need to reboot one or more devices on your network if those devices were previously allocated an IP address in the range you have now excluded from DHCP (but this is a one-off thing).

Now you can manually configure the IP address, Network Masks and Default Gateway on each machine you want to prevent from accessing the outside world. The network mask can be virtually anything so long as it's the same on all 3 machines. I'd recommend using 255.255.255.0.

Then configure the default gateway on each machine to be the same as the IP address of that machine.

Here's how the config would look (obviously each machine would have a different IP in the range you've excluded from DHCP):

Image

Once this is done the 3 machines will be able to talk to each other but will not be able to access the Internet. If your subnet mask is the same as that allocated by the DHCP server (most domestic ones these days default to 255.255.255.0) then they will also be able to talk to any machines on your local network that are using DHCP.
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Re: Networking but no internet

Postby ef37a » Tue Nov 12, 2019 12:10 pm

Thank Eddy but I had enough of trying to sort out IP addresses when I had a network camera!

Hugh, your idea seems workable. I do in fact have a Talk Talk moden/router that feeds an 8 way gigabit switch because I have 2 PCs on the network, was 3, plus a NAS drive and a smart TV so maybe I can configure the switch not to accept internet or the TT router not to pass it through?

I do not want to lose the wi fi from the router because it is a very powerful one (TTlk themselves are *holes but their router is great).

The switch is at least 5 years old, Maplins so I might need to upgrade it?

Ta' all.

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Re: Networking but no internet

Postby Temp » Tue Nov 12, 2019 12:34 pm

Could you not just use a regular router/hub with nothing plugged into the WAN port(s)? Something like this should suffice:

https://ebay.us/CpYdgM

It's got 4 Gigabit LAN connections and dual band WiFi, so should be pretty snappy. If you need conditional access to the internet (i.e. a machine that can get on the web), there's an easy to follow tutorial here:

https://www.youtube.com/watch?v=Uj5MWr3Lcoc

Cheers.
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Re: Networking but no internet

Postby ef37a » Tue Nov 12, 2019 12:37 pm

Temp wrote:Could you not just use a regular router/hub with nothing plugged into the WAN port(s)? Something like this should suffice:

https://ebay.us/CpYdgM

It's got 4 Gigabit LAN connections and dual band WiFi, so should be pretty snappy. If you need conditional access to the internet (i.e. a machine that can get on the web), there's an easy to follow tutorial here:

https://www.youtube.com/watch?v=Uj5MWr3Lcoc

Cheers.

Sorry, I don't really understand that. Note, I do not want to replace my TT router for wi-fi.

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Re: Networking but no internet

Postby Hugh Robjohns » Tue Nov 12, 2019 1:37 pm

I think he's suggesting the same as I did: use a separate modem/router for your internal isolated network (with nothing plugged into the ADSL/WAN ports).

However, if you take that approach you will inherently have two wi-fi networks in your property. One from your existing internet-connected TalkTalk broadband system, and a separate one for your newly isolated and independent internet-free internal network.

Obviously, your new W10 laptop can log into either wi-fi network as you desire, but not both at the same time.

If you want to be able to access both the internal isolated network machines and the Internet at the same time from your new W10 laptop, you will need to have everything connected on the same network system, and get into the kind of IP addressing that Drew described above to prevent certain devices being able to see the interweb.
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Re: Networking but no internet

Postby CS70 » Tue Nov 12, 2019 2:21 pm

Dave, not wanting to deal with IP addresses when making a network is like not wanting to deal with electricity when making an amplifier :D

There's nothing mysterious about it. With most home routers, every time something comes from the internet (the "gateway" that connects your lan with the nearest trunk) it's passed to all computers on the lan, and vice versa they all can use the gateway.

That's the default because usually people who connects pcs on a LAN want to see the internet without any configuration

In any router worth more than $1, you can explicitly exclude some computers from this automatic mechanism.

There's quite a few ways to do that, and which one depends a bit on your router. Which model is it?

All that said, there's a bit simpler (even if less elegant) solution, which is to use the firewall software on the individual computer itself to block anything that doesn't come from the local network. All addresses on the local network are like 192.168.x.x (the "private network" mask) so you can happily block all else. You'll have to do the same in every pc you want "off" the internet.

Obviously that won't protect you from a trojan horse attack (when one computer in your lan is subverted and becomes an enemy) but so long you have pcs in local area network, that's how it is. The only way of not having to run any antivirus or shielding is to physically keep machines off the lan.
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Re: Networking but no internet

Postby ef37a » Tue Nov 12, 2019 4:37 pm

"Dave, not wanting to deal with IP addresses when making a network is like not wanting to deal with electricity when making an amplifier"

Ooo! A rather stretched analogy CS if I might say so? If the likes of Dr Hugh feel cautious about advising me about addressing I doubt it is THAT pain free!

I have been messing with computers for well over ten years, had a good dozen through my hands and I have made some of them work on a network by using the "wizards" (for which I STILL think XP was best!) I only got involved in IP matters when I bought an IP camera and had endless problems with it.

I suspect it is all a bit beyond me and so when the time comes I shall simply pull the RJ45s on the desktops and just plug in when I need to send a file, which is not often these days and I could in fact just transfer it on a USB stick. I assume the NAS drive can stay permanently connected?

BTW, what about my smart(ish) TV? What OS do they use and is it vulnerable?

But thanks for all the help chaps.

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Re: Networking but no internet

Postby CS70 » Tue Nov 12, 2019 4:41 pm

ef37a wrote:"Dave, not wanting to deal with IP addresses when making a network is like not wanting to deal with electricity when making an amplifier"

Ooo! A rather stretched analogy CS if I might say so? If the likes of Dr Hugh feel cautious about advising me about addressing I doubt it is THAT pain free!

Ahah it's only sympathy: I know how you feel - I have the same attitude with anything implying soldering :D :D

when the time comes I shall simply pull the RJ45s on the desktops and just plug in when I need to send a file, which is not often these days and I could in fact just transfer it on a USB stick.


The plug in one is actually not a bad plan. Ethernet connections are super fast to establish.

BTW, what about my smart(ish) TV? What OS do they use and is it vulnerable?

Usually some type of embedded OS and yeah they are sort of colanders when it comes to security. Most often tough they dont really have memory and processing capacity to execute much even if you can take them over.
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Re: Networking but no internet

Postby wireman » Tue Nov 12, 2019 7:22 pm

ef37a wrote:Thank Eddy but I had enough of trying to sort out IP addresses when I had a network camera!
.

I think this is the best way forward, it is what I would do.
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Re: Networking but no internet

Postby The Elf » Tue Nov 12, 2019 7:30 pm

It seems to me that trying to avoid these computers being on the net is more trouble that it's worth. Just because they can access the net doesn't mean you have to - and if you *should* need net access with them it will make life easier!
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Re: Networking but no internet

Postby ef37a » Tue Nov 12, 2019 8:01 pm

The Elf wrote:It seems to me that trying to avoid these computers being on the net is more trouble that it's worth. Just because they can access the net doesn't mean you have to - and if you *should* need net access with them it will make life easier!

So, you are saying that so long as I don't actually log on to my browser I am pretty safe?

In fact I could uninstall Fire fox (the least worse one I have found so far!)
I cannot it seems get rid of IE 11? I don't use it much except it is the only browser I have found that does "Save Target As" which I often find useful. I suppose W10 will deny me that?

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Re: Networking but no internet

Postby The Elf » Tue Nov 12, 2019 9:43 pm

Well there are no guarantees in life, but it just seems to me that you're having to jump through hoops to avoid something that most peoples' computers are doing day in, day out - sitting on the net for when they're needed.

Yes, you're going to get updates, and yes, software may dial home to discover if a new version is ready, but... your choice.

You can do 'Save Target...' with most any browser - it may just be called something else. In Firefox it's 'Save Link As...'
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Re: Networking but no internet

Postby ef37a » Tue Nov 12, 2019 9:57 pm

The Elf wrote:Well there are no guarantees in life, but it just seems to me that you're having to jump through hoops to avoid something that most peoples' computers are doing day in, day out - sitting on the net for when they're needed.

Yes, you're going to get updates, and yes, software may dial home to discover if a new version is ready, but... your choice.

You can do 'Save Target...' with most any browser - it may just be called something else. In Firefox it's 'Save Link As...'

Well I assume I won't get W7 updates for much longer? All my updates are set as "notify" anyway.

I am sure I tried Save Link as Elf and all I got was the, er, link! Not the .pdf (which is what I most commonly want) But I shall give ot another do...

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Re: Networking but no internet

Postby blinddrew » Tue Nov 12, 2019 10:42 pm

Hugh Robjohns wrote:and get into the kind of IP addressing that Drew described above
I never said a word guv! I wasn't even here!
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Re: Networking but no internet

Postby The Elf » Tue Nov 12, 2019 10:47 pm

ef37a wrote:I am sure I tried Save Link as Elf and all I got was the, er, link! Not the .pdf
Quite simply... that means you weren't clicking on the PDF file link, but most likely to a link that was taking you to where the PDF was to be found!

In Firefox, if you look at the bottom of the window when you hover over a link, Firefox will tell you what that link is - you would want something with '.pdf' at the end.
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Re: Networking but no internet

Postby Hugh Robjohns » Tue Nov 12, 2019 10:50 pm

blinddrew wrote:
Hugh Robjohns wrote:and get into the kind of IP addressing that Drew described above
I never said a word guv! I wasn't even here!

:oops: Oops, sorry... I meant Eddy...
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Re: Networking but no internet

Postby Eddy Deegan » Wed Nov 13, 2019 2:18 am

This is turning into a bit of a mountain out of a molehill.

If you want a PC on your network not to connect to the Internet under any circumstances, just set the default gateway to be the same as the IP address of the PC. It's really that simple.

The additional stuff about manual IP configurations and configuring the DHCP settings on the router is only to prevent the configuration from resetting itself on reboot. Of course you can Take It Or Leave It but it's really trivial stuff, takes little effort to set in stone forever (or until you decide to change/revert it), doesn't require additional hardware and is a lot less hassle than setting up certain printers or cameras I could mention!
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Re: Networking but no internet

Postby Eddy Deegan » Wed Nov 13, 2019 2:33 am

ef37a wrote:In fact I could uninstall Fire fox (the least worse one I have found so far!)
I cannot it seems get rid of IE 11? I don't use it much except it is the only browser I have found that does "Save Target As" which I often find useful. I suppose W10 will deny me that?

Uninstalling Firefox does not (and I think it's safe to say never will) get rid of IE but that's moot because you really shouldn't be using IE anyway. Even Microsoft say so, and only provide it for 'compatibility' purposes.

The only explanation I can think of to account for what you're saying would be if you'd previously assigned Firefox as the default application to open links, and after uninstalling it it may not have reverted that default back to IE.

Windows 10 will certainly not deny you the ability to right click and 'save link/target as...' (in whatever format the browser of choice presents that option). I do it all the time :)
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