Re: OSX - 'no route to host'

[David Fifield <david () bamsoftware com>]

On Sat, Aug 13, 2011 at 12:19:16AM -0400, Brandon Applegate wrote:
> I've seen a few messages on this, but no decent replies or solutions.  In 
> fairness, the most accruately scoped message wasn't on this list but  
> rather a macports one:
>
> http://lists.macosforge.org/pipermail/macports-users/2011-March/023882.html
>
> On OSX (I have access to and have tested 10.6.8 + 10.7) nmap frequently  
> reports 'no route to host' - specifically when I do a ping scan (-sP).
>
> sendto in send_ip_packet_sd: sendto(4, packet, 40, 0, 192.168.64.5, 16) 
> => No route to host
> Offending packet: ICMP 192.168.64.21 > 192.168.64.5 Timestamp request  
> (type=13/code=0) ttl=48 id=6230 iplen=10240
> Sleeping 15 seconds then retrying
>
> Sometimes it completes the scan on my home net /24 without fuss.  But 
> most of the time it gets bogged down with the above.
>
> I thought perhaps there was a sysctl doing some kind of ICMP rate 
> limiting (and there is) - however tuning it to 0 didn't seem to have an 
> effect.
>
> Thanks in advance for any info.

What's your output for "nmap --iflist"?

I have seen OS X creating and destroying routes ephemerally sometimes.
What happens if you ping the IP address immediately before trying to
scan it? Does "nmap --iflist" differ immediately after a ping?

David Fifield
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