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    TFTP not working across LAN segments (UDP no cksum issue?)

    Scheduled Pinned Locked Moved Firewalling
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    • K
      klubar
      last edited by

      A have 2 LANs on my network (separate) interfaces:

      LAN:  192.168.10.0/24
      PHONESYS: 192.168.1.0/24

      Issue: TFPT requests from LAN to PHONESYS are not working.

      Diagnostics:
      Doing a packet capture I can see the request from 192.168.10.182 to 192.168.1.31 port 69 on both the computer (.182 using Wireshark) and on the PFSense on the LAN interface (using Diagnostic->Packet Capture).

      A packet capture on the PHONESYS interface shows

      The TFTP request
      12:38:59.488859 00:08:a2:09:d9:f3 > 00:e0:07:02:ed:47, ethertype IPv4 (0x0800), length 66: (tos 0x0, ttl 127, id 22020, offset 0, flags [none], proto UDP (17), length 52)
          192.168.1.1.8847 > 192.168.1.31.69: [udp sum ok]  24 RRQ "nasystem/who_is" octet

      12:38:59.490535 00:e0:07:02:ed:47 > 00:08:a2:09:d9:f3, ethertype IPv4 (0x0800), length 149: (tos 0x0, ttl 99, id 4823, offset 0, flags [none], proto UDP (17), length 135)
          192.168.1.31.4134 > 192.168.1.1.8847: [no cksum] UDP, length 107

      Yet this response never makes it back to the LAN interface.

      Any ideas or suggestions? (Is it an issue with the no checksum?)

      If it's any help, it's an Avaya IP Office on the PHONESYS interface.

      Thanks

      Firewall rules: Allow * FROM and TO LAN/PHONESYS

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      • JKnottJ
        JKnott
        last edited by

        Any ideas or suggestions? (Is it an issue with the no checksum?)

        UDP checksum is optional on IPv4 (mandatory on IPv6).  What does Wireshark show for it?  If it's all zeros, then a UDP checksum is not used for that packet.

        PfSense running on Qotom mini PC
        i5 CPU, 4 GB memory, 32 GB SSD & 4 Intel Gb Ethernet ports.
        UniFi AC-Lite access point

        I haven't lost my mind. It's around here...somewhere...

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