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Re: [bug] nexthost: failed to find route to XXX (directly connected, with --randomize-hosts)
From: David Fifield <david () bamsoftware com>
Date: Tue, 17 Apr 2012 15:57:01 -0700

On Tue, Mar 27, 2012 at 09:42:24PM -0700, David Fifield wrote:
On Mon, Mar 26, 2012 at 02:05:52PM -0500, Daniel Miller wrote:

Ran into what I think is a bug related to hostgroups and the
--randomize-hosts argument. Before I start speculating wildly,
here's what's going on:

My subnet is XXX.XXX.64.0/21, my IP is XXX.XXX.69.208, and I want to
scan XXX.XXX.0.0/16. I am also using the --exclude-file option to
exclude about 6 /24 subnets, and using the --randomize-hosts
argument. Host discovery goes well, but during the port scan, I get
"nexthost: failed to find route to XXX.XXX.68.0", and the scan ends

That's an interesting case. During the ping scan, is it breaking the
targets into many tiny little hostgroups because the ones that are
direct are not contiguous?

While investigating, I noticed that the target_needs_new_hostgroup
function in targets.cc checks for "Different direct connectedness,"
but the same function in nmap.cc does not. Is this something that
should be put there?

Yes, probably, from a quick look. I only wonder about the tiny little
hostgroups and if we should do something about that.

So I don't know why the two versions of target_needs_new_hostgroup
differ so much. I've just made it so they are the same, which will
hopefully solve the problem you saw.

I tried making a C++ template to abstract away the slight data structure
differences in the two versions of the function, but couldn't make that
work right away.

David Fifield
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