Sharing a network printer between two LAN networks



  • Hello all, I apologize for starting a new topic but I have searched and can't find the solution.

    I have Pfsense set up as a router with three NIC's. The first one is WAN - standard cable internet. The second one is LAN (10.1.0.1/24) - allows one of the office computers and the public wifi WAP's so it is an open network. The third is BACKOFFICE (10.2.0.1/24) and it is a closed network that has all the Point-Of-Sale computers and printers, and credit card terminals, and can't be accessed by the LAN or the public. It only uses the WAN to process credit card payments. Everything is working fine the way it is supposed to. Pfsense is a lifesaver in this regard and I've saved thousands (I am a restaurant owner and chef, but a computer hobbyest so I have the basic sense of networking down). So thanks!

    I have a wireless laser printer that is currently on the LAN network that I use to print everyday things (applications, tax forms, receipts, etc.) But I need the BACKOFFICE network to print a daily report of credit card transactions as well. So far, I've tried a bunch of different firewall rules but I can't get BACKOFFICE to find the printer.

    The printer's IP is 10.1.0.73. Due to the very small, brick-like, and the "I don't need more heat in here" nature of the server room the large laser printer is in a separate room so it has to be connected wirelessly.

    TL;DNRWhat firewall rule would allow 10.2.0.50 to connect to 10.1.0.73? Thanks so much for the help!



  • @amcoolio:

    …I can't get BACKOFFICE to find the printer.

    Try to ping it's IP from the computer you want to print from.

    "Finding" a printer is difficult across subnets because that's handled by broadcasts which are not routed between subnets.
    However, you can add the printer manually with the IP specified. You will be able to print if rules permit. Just not find it or "see" the printer in network neighborhood.



  • Pings fine, 5ms. However when I try to add it manually in Windows it can't connect to the printer.  Nor can the Brother software find the printer when typing the IP manually.



  • Your firewall rule(s) allow traffic from 10.2.0.50 host to your printer's IP for TCP and UDP protocols on any ports?



  • Sorry for the late reply. Yes, I added those rules. I can ping the printer through the command prompt just fine, but when I try to do so in a browser, I get connection timed out.

    I even tried a rule that allows the BACKOFFICE Net to reach the LAN Net, but to no avail.

    I guess the printer doesn't like talking across networks? 10.1.0.73 -> 10.2.0.50


  • LAYER 8 Global Moderator

    "I guess the printer doesn't like talking across networks? 10.1.0.73 -> 10.2.0.50"

    Well does your printer have a gateway set?  If not then no its not going to be able to talk across networks.  When you say you can ping it.. Your pinging it from where?



  • Instead of punching a hole in your firewall for the industry's most hackable device (printers) would it be possible to do cloud printing instead with it?

    I also run a pci compliant network and printers are my worst issue by far.


  • LAYER 8 Global Moderator

    Allowing your 1 vlan to talk to your printer on your other vlan not really suer I would call that punching a hole in your firewall ;)  How would use cloud printing make that more secure?

    While I don't agree with open all ports to the printer.. Sure doesn't need UDP to print.. Depending on the printing protocol he is using, they just need to open that tcp port.



  • @amcoolio:

    … in Windows it can't connect to the printer...

    You have set your Windows firewall to allow traffic to the other subnet (which Windows sees as non-local)?


  • LAYER 8 Global Moderator

    Where did he say this printer was being shared off a windows machine?

    "I have a wireless laser printer that is currently on the LAN network"



  • @johnpoz:

    Allowing your 1 vlan to talk to your printer on your other vlan not really suer I would call that punching a hole in your firewall ;)  How would use cloud printing make that more secure?

    While I don't agree with open all ports to the printer.. Sure doesn't need UDP to print.. Depending on the printing protocol he is using, they just need to open that tcp port.

    Oh, then he's not compliant.  The cc processor must be separated by a firewall.


  • LAYER 8 Global Moderator

    Where does it say that the printer the cc processor prints to can not be on a different network?  He is not opening up traffic to the cc proc, he is opening up the cc proc to talk to the printer.

    He does have a firewall, he just needs to open the ports to the printer.  He is prob trying to find the printer via broadcast or something?  If he is trying to use something like airprint for example that is not going to work out of the box across segments.  Would need something like ahavi to allow the discovery of the printer.

    His rule on his backoffic interface is pointless since he has any any rules there.  So that first rule is just not needed at all.

    Can you ping the printer?  What are you using for wifi?  You didn't put it behind a nat did you?  Can you ping the printer from your backoffice network?



  • @johnpoz:

    Where does it say that the printer the cc processor prints to can not be on a different network?  He is not opening up traffic to the cc proc, he is opening up the cc proc to talk to the printer.

    He does have a firewall, he just needs to open the ports to the printer.  He is prob trying to find the printer via broadcast or something?  If he is trying to use something like airprint for example that is not going to work out of the box across segments.  Would need something like ahavi to allow the discovery of the printer.

    His rule on his backoffic interface is pointless since he has any any rules there.  So that first rule is just not needed at all.

    Can you ping the printer?  What are you using for wifi?  You didn't put it behind a nat did you?  Can you ping the printer from your backoffice network?

    Agreed, that's what we use.  So ok, pci dss requires the processor and registers to basically be on their own subnet that is separated by hardware.  At least, that was my interpretation at the time.  Though as long as the device is business and not personal, it is allowed on the same subnet.  His separation of devices may be unnecessary.

    Airprint would require internet access to the printer which, yes, is another can of worms.  However, printers are most vulnerable physically from what I've gathered.


  • LAYER 8 Global Moderator

    airprint requires no internet access…  But it does require the device using the printer to be on the same layer 2 to discover it.

    The OP has not stated how he is trying to print, what protocol, what printer.  His backoffice rules are any any.. So anything on that network would be able to access anything on the lan.  Unless there was software firewall on the lan devices..

    I print from multiple segments all the time to my printer.  You just add the IP in the driver on your device, and open the ports your using.. 9100 is a common printer port for example.  But like I said his rules are any any so he has something else going on..  Like his wifi is behind some nat router plugged into his lan???  Once the OP gives some info to work with we can help him find his problem.



  • @johnpoz:

    airprint requires no internet access…  But it does require the device using the printer to be on the same layer 2 to discover it.

    The OP has not stated how he is trying to print, what protocol, what printer.  His backoffice rules are any any.. So anything on that network would be able to access anything on the lan.  Unless there was software firewall on the lan devices..

    I print from multiple segments all the time to my printer.  You just add the IP in the driver on your device, and open the ports your using.. 9100 is a common printer port for example.  But like I said his rules are any any so he has something else going on..  Like his wifi is behind some nat router plugged into his lan???  Once the OP gives some info to work with we can help him find his problem.

    Oh right - I was thinking cloud printing.

    Yeah who knows what OP has got going on.  Airprint is supposed to be close to NFC just through the wireless of the printer and device sending the print.  Logistically that may be impossible so what I was really recommending is cloud printing if OP does indeed need to separate his lan.


  • LAYER 8 Global Moderator

    how would could printing be compliant?



  • Oh just like any other web service, I guess.  Shouldn't impact him any more than having the firewall open for the printer on whatever ports he's going to use.

    It would only be a compliance issue if the printer was for personal use and on the business network, or if the device somehow opens ports on the wan firewall that a scanner would pick up.  Or if he somehow managed to be plugged into the ethernet of the business and the wifi portion connected to the guest.  You know, crazy stuff that happens by accident all the time.


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