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Date:      Tue, 7 Aug 2007 15:37:50 -0700
From:      Chuck Swiger <cswiger@mac.com>
To:        Adam J Richardson <fatman.uk@gmail.com>
Cc:        freebsd-questions@freebsd.org, Modulok <modulok@gmail.com>
Subject:   Re: Bizzare routing table entry.
Message-ID:  <86731548-011A-4BFF-8D52-25819C00735B@mac.com>
In-Reply-To: <46B8EE80.7000905@crackmonkey.us>
References:  <64c038660708071210w1950ccccwda1bb8464587d1de@mail.gmail.com> <46B8EE80.7000905@crackmonkey.us>

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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.

-- 
-Chuck




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