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MorioSnek
MorioSnek
New Member
January 5, 2022
Question

AirPrint Multicast in NAT mode

  • January 5, 2022
  • 1 reply
  • 5739 views

Hi everyone,

I recently installed a FortiGate 60E in my home network, that I share with few other people. For certain reasons, I don't have an administrative access to the home gateway, so I had to set my FGT in NAT mode. Everything's fine, but the other people in the house have to print on the HP printer that is in my network. So I tried setting up multicast policies, but nothing has worked until now.

 

The "outer" network is connected through WAN1, and its net address is 172.16.4.0/24.

My network is 192.168.4.0/24. The printer is connected to an airport extreme in bridge mode, which is connected to the internal FGT switch.

The multicast policies I set are basically two: one from 172.16.4.0/24 to all the services (from WAN1 to Internal) and the other one from the printer (192.16.4.113) to all the services (from Internal to WAN1).

Leaving all the security issues aside that I will think about later, I can't see from my network all the multicast devices that are on the outer network, like TVs, stereos...

I set up firewall policies that allow traffic between 172.16.4.0/24 and the printer, but I'm not sure if the NAT should be allowed or not.

Thank you in advance

1 reply

AlexC-FTNT
Staff
AlexC-FTNT
Staff
January 6, 2022

Did you allow mulicast forward on the system settings?

You can try and follow this guide:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Airprint-multicast-forwarding-between-two/ta-p/198625

MorioSnek
MorioSnekAuthor
New Member
January 6, 2022

Hi Alex,

I followed that guide, and basically I had to enable all the protocols through the interfaces, and disable multicast routing (I already had multicast forward enabled).

The thing is, now that I can view the printer from the outer network, I try to print, but the communication between the device and the printer is stuck on "Printing" without any response from the printer. Do you know how can I solve this issue?

Thanks

AlexC-FTNT
Staff
AlexC-FTNT
Staff
January 6, 2022

First see where the problem is - does the traffic pass both ways to/from the printer (run a packet capture) ? and if not, see why the FortiGate blocks them (debug flow)

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