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UDP Broadcast Forwarding Between Subnets

ms flag

We have an application that broadcasts UDP to allow for the detection of IP Based Systems on a network by an in house application.

We widely use Open Source and especially PFSense. It seems you cannot merely route UDP Broadcasts and indeed why would you - you need an active Daemon similar to Cisco's IP Helper to catch packets and drop in out into the other subnet.

The problem is - our applications use ephemeral ports for duplex, the comms is started on one port and then continues on another ephemeral and back.

From my wiresharks - it appears that this is when comms breaks using both the pfsense and opnsense tests as they both require the choice of specific ports to work correctly.

Does anyone have an suggestions?

cn flag
Do what BOOTP/DHCP does. Create a forwarder for your application to forward your UDP broadcasts to the appropriate network(s). Or have an agent on each VLAN/subnet.
JakeFury avatar
ms flag
Hi Greg, Indeed - but how to forward all the traffic when ephemeral ports are used?
Score:0
ms flag

This is the answer - and it works

https://github.com/udp-redux/udp-broadcast-relay-redux

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