Broadcast UDP packets



  • Hi all,

    i have 2 local subnet: Lan_client, Lan_server on a pfsense 2.0.3. We have an ups software running on machines over both networks but they cannot see each other: who is in  lan_client can check status on the same subnet only. Same on lan_server. Going deep with tcpdump i discovered this software use broadcast on udp port 18880
    Then i setup avahi and igmp proxy (with a rule to pass igmp with opts) thinking to solve just adding a nat rule to forward traffic to my box.
    Later on i realized that traffic sent by ups software is 255.255.255.255:18880 and then doesn't match my nat rule (nor using "any" or 255.255.255.255 inside nat rule)

    Do i have to use any udp proxy? is there a chance to convert broadcast to multicast or are there any other routing solution for broadcast?

    thanks in advance



  • IGMP and Avahi forward multicast, not broadcast. You don't want to forward broadcast between subnets. A UDP proxy potentially could if you want to do a lot of hacking yourself. It's likely the UPS software supports defining UPS by IP and not relying on broadcast for discovery. Any business-grade software will give you an alternative since multi-subnet networks are the norm and forwarding broadcast on such networks is nearly unheard of.