Re: Issues with privileged scan of LAN on Mac OS X

[David Fifield <david () bamsoftware com>]

On Sun, Jan 27, 2013 at 01:01:04PM +0100, Jesper Kückelhahn wrote:
> I'm seeing some strange behaviour when running privileged scans
> against hosts in my LAN. nmap marks the target as being down, but if I
> run unprivileged, it works fine. This does not happen when scanning
> external targets. I've checked out previous revisions (back to
> r30000), to see if it might be a patch that broke something, but I
> haven't found any differences. Could this issue be caused by a change
> in OS X ? Unfortunately, I don't have access to previous versions (I'm
> on 10.8.2), so I can't test if this is the case.

It looks like something to do with ARP host discovery. ARP host
discovery is only done when privileged, and only for targets on the same
subnet. A workaround that disables ARP host discovery is to use the
--send-ip option.

Try these commands too.
        netstat -rn
        nmap --route-dst 192.168.1.23
OS X has been known to change the routing table on the fly, so you
should check the routing table before and after a scan to see if it
changes.

David Fifield
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