Re: nmap -sP does not populate arp table

[Fyodor <fyodor () insecure org>]

On Wed, Feb 29, 2012 at 05:44:35PM -0800, Michael Convey wrote:
> I used the command "nmap -sP" for host discovery, but also with the hope
> that it would populate my host's ARP table. Although, I'm getting the
> expected output from the nmap command, my ARP table is not being populated.
> When I ping the hosts individually, the ARP table is populated.
>
> The following seems to imply that nmap -sn (formerly nmap -sP) sends ICMP
> echo requests just like ping:
>
> http://nmap.org/book/man-host-discovery.html
>
> What am I doing wrong?

Hi Michael.  By default on Linux and most other platforms, Nmap sends
ARP requests on the LAN itself, so the OS doesn't add it to its ARP
table.  However, if you run Nmap with the --send-ip option, Nmap uses
the OS raw sockets interface and your ARP table should get populated.

Cheers,
-F
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