How to handle Telnet access to industrial control appliance
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I need to have remote access to a piece of industrial control hardware that utilizes Telnet to access its user interface. Currently I have this on my LAN (only). The device is pretty recent but will not receive firmware updates from the manufacturer any longer.
Minimally, I need read access; to that end I may explore some PuTTY scripting to have it run a report at some interval (with the info I need to view, less than 20 data points) and save it in my network where it would be picked up by my automatically-synced cloud storage and I could view the information that way. That's a real roundabout way though.
I would really like read/write (command) access though via Telnet. Is nginx something I could use here? Or what should I do?
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@NGUSER6947 can't you get VPN access to that LAN, that's the most secure way.
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@patient0 If I create a VPN on my pfSense does that force everything on my network to run through that VPN? I've only used VPNs from tbe client end (i.e. proton on all of my devices), so I don't have a good sense of how it would work on my oun router.
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@NGUSER6947 no creating a vpn does not force traffic through it.. so you are remote to this pfsense right - just vpn into pfsense, and then telnet to what you want to telnet to.
You can setup your vpn to be as restrictive or open as you want - you could allow access to anything, or you could limit to only this telnet devices IP on telnet port.
Another way less config needed would be to port forward to this telnet IP on pfsense wan, but only allow your specific source IP.. If you know the IP where you will be coming from.. This would be secure, but not as elegant of a solution. And the traffic over the internet would not be encrypted inside a vpn tunnel.
Another way to skin the cat would be to ssh to pfsense wan, then telnet from pfsense to the telnet box. This would be encrypted over the internet.. And if you only allow public key auth to ssh on pfsense, this would be pretty secure.. Still not as good a vpn setup, you could limit to your source IP as well, etc. To prevent spam noise of boxes hitting ssh, changing the port would cut down on log spam as well.
But the best solution is setup vpn to pfsense.
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Yup setup a VPN server and use it remotely. Solved!
https://docs.netgate.com/pfsense/en/latest/recipes/openvpn-ra.html
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Ok appreciate the feedback. Looks like the VPN is the right way to go.
Follow up question, can my SG-1100 handle this additional application? Currently I'm running pfBlockerNG.
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Yes. It doesn't really use any significant resources just to run the server. It will when the VPN is connected but that depends on the traffic over the VPN. If that's just some telnet traffic it's not a problem.
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@stephenw10 Excellent thank you.
