Pfsense, Duplicate and Retransmission packets on different ports

  • Recently I found that my machines report a number of odd blocked traffic on their firewalls.
    After analyzing the network briefly with wireshark, I discovered the machines were receiving Duplicate and Retransmitted packets from my pfsense router.

    What was odd was the volume, dozens of hits. The traffic was coming from the same remote IP addresses the machines were normally connecting to, but these packets were on (different) much higher port numbers: ports 40,000-65,000. Also, some duplicate traffic was coming from the DHCP server itself.

    These packets occur even with only a single machine attached. I don't really know much about Duplicate and Retransmitted packets (I have no idea how to address it).

    My question is more: Should duplicate and retransmitted packets be seen on the wrong ports, or is this a sign of malicious activity?

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