Re: Nping not sending UDP broadcasts

[David Fifield <david () bamsoftware com>]

On Tue, Sep 21, 2010 at 07:46:48PM +0200, Luis MartinGarcia. wrote:
> On 09/18/2010 09:28 PM, David Fifield wrote:
> > On Sat, Sep 18, 2010 at 08:39:45PM +0200, Luis MartinGarcia. wrote:
> >   
> > > Hi, David.
> > >
> > > Thanks for the report. I've just added a to-do item for this. I guess
> > > making a setsockopt() call for the SO_BROADCAST option will fix it.
> > > Hopefully, next week I'll have some free time to fix this and the
> > > nsi_delete() problem. 
> > >     
> > I think you can use nsp_setbroadcast.
>
> I've been looking into this but I haven't been able to find the problem.
> Using nsp_setbroadcast(nsp, 1) does not help. I've seen that this only
> happens for broadcast addresses for your current subnet (in my case
> fails for 192.168.1.255 but works for any other .255). Also, I've found
> that sending the packets at the raw ethernet level works fine (option
> --send-eth).

I checked this out some more. When I was running before, I was running
as root. The problem also exists for unprivileged UDP, but the error
looks different:

$ nping --udp 192.168.0.255 -d

Starting Nping 0.5.35DC18 ( http://nmap.org/nping ) at 2010-09-21 13:32 PDT
ERR: (0.0000s) CONNECT to 192.168.0.255:40125 failed: Permission denied
ERR: (0.0000s) WRITE to 192.168.0.255:40125 failed: Destination address required

Calling nsp_setbroadcast in ProbeMode::init_nsock fixes that for me. I
committed it.

For privileged mode, I think you need to call setsockopt on rawipsd.
Sorry, I thought that privileged mode was using Nsock also, but it has
to be done separately.

David Fifield
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