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Date:      Thu, 19 Mar 1998 16:19:24 -0600 (CST)
From:      "Matthew D. Fuller" <fullermd@futuresouth.com>
To:        GLEN.W.MANN@monsanto.com
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: arp/IP to ethernet addresses
Message-ID:  <Pine.BSF.3.96.980319161634.20071N-100000@shell.futuresouth.com>
In-Reply-To: <"0319194046-arp/IP to ethernet addresses"@MHS>

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On 19 Mar 1998 GLEN.W.MANN@monsanto.com wrote:

>      Hello!
>      
>      On the network at work, we would like the ability to match ethernet 
>      addresses (e.g., 00:a0:24:12:34:56) to IP addresses.

Dynamically?
Or once-over?
For what purpose, if I may ask?

>      The output for `arp -a' is confusing.  It shows more IP addresses than 
>      there are hosts in our DNS namedb tables, but not a full listing of 
>      all the machines on the network.  What other than explicit action, 
>      updates the arp tables?  Some time ago, `arp -a' showed me many more 
>      entries, perhaps all the machines on the network.  Is there a way to 
>      cause the translation tables to be more complete?

I'm not sure exactly what you're saying here.  The arp tables should hold
every MAC address that the host has talked to (fairly recently) on the
local network, with no routers in between.  If they haven't talked,
there's no MAC address stored.

>      If I build a script to send pings (one per) to each possible IP 
>      address on the net, the arp table is built.  Is this a good idea?

Might be better to ping the broadcast address once.
Unless is breaks your network with the load, I can't imagine it's
necessarily a *bad* idea.  Doesn't mean it's *good*, but...

>      The man pages say the arp stuff works with 10Mbit ethernet, though it 
>      seems to work with 100Mbit as well.  I guess the man pages are 
>      outdated?

Never thought of it that way.  I always thought of arp as a function of
Ethernet, regardless of speed.  *shrug*



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|       FreeBSD; the way computers were meant to be       |
* "The only reason I'm burning my candle at both ends, is *
| that I haven't figured out how to light the middle yet."|
*    fullermd@futuresouth.com      :-}  MAtthew Fuller    *
|      http://keystone.westminster.edu/~fullermd          |
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