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Re: [lwip-users] sending an ip adress to a ethernet box without knowing


From: Ian Guffick
Subject: Re: [lwip-users] sending an ip adress to a ethernet box without knowing the ip but the MAC
Date: Wed, 12 Nov 2003 21:29:08 -0000

----- Original Message ----- 
> Message: 2
> Date: Tue, 11 Nov 2003 11:49:58 -0500
> From: address@hidden
> Subject: Re: [lwip-users] sending an ip adress to a ethernet box
> without knowing the ip but the MAC
> To: Mailing list for lwIP users <address@hidden>
> Message-ID:
> <address@hidden>
> Content-Type: text/plain; charset="us-ascii"
>
> Odds are RARP won't be installed on your windows box unless it's
> configured as a BOOTP server.
>
> An inelegant solution would be to ping every node on your subnet then
> parse the output of "arp -a". If the overhead doesn't kill you, this
> should take just a few minutes to whip up.
>
> Larry Piggins
> address@hidden
> 248-596-3343
>

I've never tried this with lwip, but you should be able to use IP-Gleaning.
And manually enter an ARP entry into your Windows box.  Then try sending a
packet.

I've had this working on a non-lwip system I'm working on.

e.g. your lwip board has the MAC address 00:01:02:03:04:05, but no IP
address.
You want it to have the IP 192.168.1.10
On your windows box enter :-   ARP -s 192.168.1.10 00:01:02:03:04:05
If you now ping 192.168.1.10, an ARP entry is already there, so an ARP
conversation is not performed.
So a packet is sent with the specified IP and MAC address.
IP-Gleaning simply looks for this packet and presumes (sometimes wrongly!)
that the IP belongs to itself.

RARP is the 'correct' method, this is a bit of a work around it you dont
want to use a RARP server.

BR,
Ian






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