Re: Parallelism across multiple interfaces

[David Fifield <david () bamsoftware com>]

On Wed, Sep 15, 2010 at 07:22:15PM +0200, Kristof Boeynaems wrote:
> Does Nmap support parallel scanning across multiple interfaces?
>
> I have a multi-homed Linux system running Nmap with about 20 (virtual)
> interfaces, each in a different network. I also have a list of about
> 80 IP addresses, spread over these 20 different networks (about evenly
> distributed, let's assume 4 per network).
>
> I am trying to run a UDP scan on all those 80 hosts, as follows:
>
> # nmap -n -r -T4 -PN --min-hostgroup 100 -sU -iL [file with 80 IP
> addresses] -oA [filename].
>
> I was hoping that the min-hostgroup option would force Nmap to scan
> all 80 IPs in parallel. However, that does not happen, presumably
> because Nmap automatically splits the scan up in multiple groups, one
> group per interface, as explained in the documentation:
>
> "Nmap may have to use smaller groups than you specify if there are not
> enough target hosts left on a given interface to fulfill the specified
> minimum." [1]
>
> Is there a way to force Nmap to scan from multiple interfaces in parallel?

No, there's no automatic parallelism across multiple interfaces. The
best workaround is what you suggested, to split up the targets and run
multiple Nmap instances. You can use Zenmap to view the results of
combining the scan outputs together.

David Fifield
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