Wireless Router, WiFi, and a laser cutter

[fog37]

TL;DR Summary

Wireless Router, WiFi, and laser cutter

Hello,

I have a laser cutter which can connect to a wireless router via an ethernet cable. My laptop accesses the internet through the wifi provided in the office (I don't have access to a broadband modem).

Is it possible to simultaneously be connected to the internet, via wifi, and at the same time be connected to the laser cutter through the wireless router? How? I can disconnect the laptop from the wifi and connect it to the wireless router to access the laser cutter but I would like to not have to disconnect from the internet and jump on the router everytime I need to use the laser cutter...

Thanks!

 

[jedishrfu]

Get a router, use the Ethernet cable and plug it into a wireless router and connect your laptop to the wireless router.

to be able to browse the web and control your devices you’ll need to connect the router to the internet Which means someone can hack your devices too ie they are one the same shared network.

sharing your laptop and internet with another computer via the lan cable.

https://www.dummies.com/computers/pcs/how-to-share-your-laptops-internet-access-with-another-pc/

To have a computer on two separate networks simultaneously means you’d need two separate network cards and I’m not sure how you can do that with a laptop without some special usb gadget.

 

[fog37]

Thanks jedishrfu.

1. I see your point of needing two different network cards to be on two different networks at the same time. That is not my situation.
2. If I was at my house instead of at the office at work, I could connect the wireless router to the broadband modem (WAN port on the router). The broadband modem essentially brings an ethernet signal into the home. The wireless router would then allow me to both surf the internet and use the laser cutter. The laser cutter, when it boots, has its own IP address and an ethernet port. I guess I would need to get an ethernet to wi-fi adapter for the laser cutter in that case.
3. Since I am not at home but at work in an office and don't have access to the school's broadband modem, I guess my only choice is to surf the web using the school's wifi and disconnect from the wifi and connect to the router wirelessly when I want to use the laser cutter with the cutter connected to the wireless router.

 

[sysprog]

No. Dangerous. I think that when you are learning about net things and remote control that 'laser cutter' should not be part of the question.

 

[fog37]

Hi sysprog, I see what you mean. But I am talking about being in the same room as the laser cutter, just the convenience of not having everyone need to connect the cutter directly to the laptop.

 

[sysprog]

How about let's don't nobody ever get cut by the laser cutter; what the eff? if you're a kid who is learning RC please don't go for laser cutters instead of hot wheels toys.

 

[fog37]

thanks sysprog.

We have the laser cutter and we would like to use it (safely). The wireless connection is often recommended.

 

[jedishrfu]

@sysprog has a point. You really don't want a hacker to control your laser cutter so a wired LAN connection would be better than a wireless connection.

Imagine some teenager thinking its funny to hack into your business and fire up the laser cutter causing a fire.

 

[Merlin3189]

I'm not sure what your problem is. If you can connect to the cutter over ethernet, then you can do it over wireless. My laptop connects to internet, printer and mass storage all over the same wifi link.
Admittedly I use Windows, so anything I plug into the network just appears on the laptop and other computers on the network.

I suppose someone could access my network via my internet connection. I might worry about their being able to access my computer and storage, but not the printer. You can always switch off the cutter when you're not there.

 

[jedishrfu]

My feeling was that he wants to access both but not have the laser cutter on the internet. This means your laptop would need two separate network cards for the laser cutter network and for the internet-connected network with your laptop being a gateway accessing both but separating the two.

 

[sysprog]

My feeling was that he wants to access both but not have the laser cutter on the internet. This means your laptop would need two separate network cards for the laser cutter network and for the internet-connected network with your laptop being a gateway accessing both but separating the two.

Not allowed Sir. You know why. DoD Orange Book 'search for covert channels' . . .

 

[jedishrfu]

@sysprog can you clarify your response, please?

 

[sysprog]

You can always switch off the cutter when you're not there.

How about 'No'. It's too dangerous. Please don't hook it up to be remotely activatable in the first place. Maybe you've never experienced forgetfulness. It feels much better to me when I wake up not scared that I may have left on something that I should have switched off or not plugged into begin with.

 

[sysprog]

@sysprog can you clarify your response, please?

I'm too lazy. A search for covert channels means inclusion of consideration of anything that you suppose that the bad guys might be trying to snoop in on or impose upon. You are a boss here so you have access to my primary email and I didn't here misrepresent regarding that. Please feel free.

 

[Vanadium 50]

The proposals seem complicated.

You have a wireless router that everybody connects to, right? Presumably it uses NAT and DHCP to assign local addresses to every computer plus the laser cutter's wireless adapter. Its built-in firewall rules should be configured to allow no sessions incoming on the internet and no external traffic at all from the cutter. Now there is one network where every computer can access the internet and every computer can access the tool, but the tool cannot access the internet in either direction.

 

[sysprog]

and every computer can access the tool,

Well for my part if I'm allowed to have a part I'm not ok with that.

 

[Vanadium 50]

But isn't that part of the point? Isn't the intent to give everyone access without plugging and unplugging?

 

[anorlunda]

I'm too lazy. A search for covert channels means inclusion of consideration of anything that you suppose that the bad guys might be trying to snoop in on or impose upon. You are a boss here so you have access to my primary email and I didn't here misrepresent regarding that. Please feel free.

Sorry but that doesn't clarify it for me. What does covert channels mean? How does it apply in this thread?

 

[sysprog]

Sorry but that doesn't clarify it for me. What does covert channels mean? How does it apply in this thread?

Sorry but I do not say. I'm not sure that you've read the Orange Book (the others are also important). I do say please carry on.

 

[sysprog]

But isn't that part of the point? Isn't the intent to give everyone access without plugging and unplugging?

Please no remote control for 'laser cutter' equipment.

 

[fog37]

Thanks everyone. This is what I am extracting from your comments:

• I would need two network cards to be on two different networks at the same time (for example, the router network and the wifi network).
• However, in a home setting where there is a broadband modem to access the internet, I could connect the wireless router to the broadband modem and have various laptops be on wifi and also be able to connect to the laser cutter or to a wireless printer simultaneously without disconnecting from the wifi, correct? The router would manage the internet signal coming from the broadband modem and provide it to the laptops and also internally interconnect the various devices (laptops, laser cutter, printers, etc.) in the house by assigning each one a unique (static or dynamic) IP address.
• On the other hand, at school or office, the institution has a network with a wireless access point that allows us to surf the web via wifi. The laser cutter, in that instance, would have to connect to the school/office network via a wired connection and be assigned an IP. Laptops connecting to the wifi would also be able to see the laser cutter and connect to it (because the wireless access point broadcasts both the wifi signal as well as the laser cutter IP, I think).

 

[sysprog]

I think that there does not exist a sane human person who thinks that a 'laser cutter' isn't dangerous.

 

[Tom.G]

On the other hand, at school or office, the institution has a network with a wireless access point that allows us to surf the web via wifi. The laser cutter, in that instance, would have to connect to the school/office network via a wired connection and be assigned an IP. Laptops connecting to the wifi would also be able to see the laser cutter and connect to it (because the wireless access point broadcasts both the wifi signal as well as the laser cutter IP, I think).

Let's see if I understand your situation correctly. At school you wish to connect YOUR laptop to both the Laser Cutter and to the school Wi-Fi without having to connect/disconnect either one to talk to the other.

Alternative 1:
Many laptops have both Wi-Fi and an Ethernet connection. If so (and that is a big if) you may be able to configure the Laser Cutter software/your laptop to use the wired connection, while the browser uses the Wi-Fi. At least some laptops have(had) different IP addresses for the wired and wireless connections.

Alternative 2:
Obtain what is called an Ethernet Switch. That's a device that has several (typically at least four) ports to which individual computer are wired. The switch repeats all incoming data from every computer to every port. Another 'Obtain' item is a Wi-Fi adapter that you connect to one of the Switch ports. Your laptop and the Laser Cutter connect to other Switch ports.

Alternative 2A:
For added security, to satisfy some of the posters here and keep the Laser Cutter off the Internet, you could add a cheap Router between the Switch and the Laser Cutter and program it to accept incoming data only from your laptop.

Alternative to Alternative 2A:
There may be routers available that can be programmed to accept/block traffic to/from particular devices or ports. If you can find one, use it in place of the switch.

There are some ideas, at least.

Let us know what, if any, resolution you find.

Cheers,
Tom

 

[ChemAir]

I'd tend to lean toward the general response of @sysprog, especially since I don't know the size or type of table we are discussing.

Most of these machines have a variety of configuration issues that often can't be verified without looking at them. These are things like torch/cutter/laser height, home position/current zero location that may need adjustment each time new material is placed in the machine for processing. Not knowing these are correct can result in a gantry crash, or a wasted part. A laser may have some additional issues (guards, optical shielding, ventilation, etc.) that need to be checked before actually starting it.

Leaving a powered device that can hit someone, start a fire, cause some type of electrical problem, or possibly just damage itself would make me very uncomfortable if anyone could start the machine from anywhere blindly. I can easily see the remote start attempted when someone else is working on the machine, possibly elbow deep in it. This would not be good. Also, if the machine stalls or glitches, no one will be there to see it happening, so they won't stop it.

My machine (6'x14' plasma table), and most other industrial CNC tables have a local control that starts and stops while an operator can observe them. There is also a local E-stop that takes power off the gantry motors. We keep the computer and controller physically isolated from our network that has internet connectivity, so the unit can't "catch" viruses, trojans, etc., without someone physically putting it there.

If you make it available from any computer remotely at any time, you have to accept that just getting near the piece of equipment may have new, possibly serious hazards associated with it. Also, this proposes potentially specialized computers be tied in some way to the internet. These "special" computers can run on outdated operating systems for stability, so they can be more susceptible to some kinds of attacks than your average PC. My Hypertherm controller was updated from DOS to windows XP about 8 years ago, and is still running a current configuration. Virus damage to some of these can take quite a while to repair if you want to save CNC data.

If it's designed and engineered to start, run, and stop remotely, with safeguards to prevent hurting people, hurting parts, or damaging equipment, that would be one case. Cobbling together a wi-fi/lan together to "open" a system that may not be designed for this is probably not a good solution without significant consideration of safeguards (cameras, interlocks, others) to prevent unintended problems.

 

[anorlunda]

Thanks everyone. This is what I am extracting from your comments:

You are ignoring the many comments that say "don't do it." Since it is safety related, such indifference is not acceptable.

Thread closed.