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Date: Sun, 28 Oct 2007 21:57:10 -0600
From: Modulok <modulok@gmail.com>
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Subject: arp: 192.168.1.1 is on lo0 but got reply from...
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One of my FreeBSD machines acts as a router, providing shared internet
access via ipfw/natd to the local network. Recently I've been getting
a lot of these in the logs:

    arp: 192.168.1.1 is on lo0 but got reply from (someEthernetAddress) on xl1

xl1 is my Internet-facing interface. The address  192.168.1.1 is
configured on the internal interface, xl0 not xl1. The address mapping
for 192.168.1.1 is a permanent entry in the ARP table. 1) After
reading the arp(4) manpage am I to assume that someone on my ISP's
side of things has something terribly mis-configured? 2) If the local
host has a permanent entry for 192.168.1.1, why would it send out an
arp request for an address it already knows (is this normal)?

Just trying to make sure it's not something I screwed up...
-Modulok-