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Date:      Wed, 8 Aug 2007 23:01:29 +1000 (EST)
From:      Ian Smith <smithi@nimnet.asn.au>
To:        Chuck Swiger <cswiger@mac.com>
Cc:        freebsd-questions@freebsd.org, Adam J Richardson <fatman.uk@gmail.com>
Subject:   Re: Bizzare routing table entry.
Message-ID:  <Pine.BSF.3.96.1070808224733.16319A-100000@gaia.nimnet.asn.au>
In-Reply-To: <20070808120020.3564C16A476@hub.freebsd.org>

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On Tue, 7 Aug 2007 15:37:50 -0700 Chuck Swiger <cswiger@mac.com> wrote:
 > On Aug 7, 2007, at 3:13 PM, Adam J Richardson wrote:
 > > Modulok wrote:
 > >>   0&0xc0a80132       link#1             UCS         0        0   bge0
 > > <snip>
 > >> 1. The first entry, it's not IPv4, IPv6 or a MAC address that I've
 > >> ever seen, what format is it?
 > >
 > > Hi Modulok,
 > >
 > > It's possible to represent IPv4 addresses as a single number. I  
 > > don't recall the algorithm for converting that four byte dot- 
 > > delimited group into an integer, though, so I can't tell you what  
 > > number it is. Perhaps you can Google the algorithm and do the math  
 > > to figure out what it is.
 > 
 > aaa.bbb.ccc.ddd => 0xAABBCCDD, where AA = hex(aaa), BB = hex(bbb), etc.
 > In particular, 0xc0a80132 is the hex equivalent of 192.168.1.50.
 > 
 > An IP address + netmask can normally be represented in the routing  
 > table via the slash notation-- say 192.168.1.50/24 meaning a  
 > 255.255.255.0 (or 0xffffff00) netmask.  Non-contiguous netmasks are  
 > represented by "address & netmask", but since no normal network ever  
 > uses such a netmask, they almost always represent a  
 > misconfiguration-- someone confused the arguments such that the route  
 > command interpreted the gateway IP as a netmask instead.

Been there; in my case it was a rogue route added by an ifconfig with an
incorrect - as you say, non-contiguous - netmask.  In this case it might
have been specified/interpreted as 0.0.0.0 netmask 192.168.1.50 ?

Cheers, Ian




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