Re: ncat broadcast support?

[Daniel Miller <bonsaiviking () gmail com>]

Thanks for the tip, Ron! Here's what I came up with, which works for me 
for this particular application.

--- nmap.orig/nsock/src/nsock_connect.c    2010-05-12 09:09:20.663173832 
-0500
+++ nmap/nsock/src/nsock_connect.c    2010-05-11 16:32:33.347640392 -0500
@@ -120,6 +120,14 @@ void nsock_connect_internal(mspool *ms,
       }
     }

+    if (sin->sin_addr.s_addr == INADDR_BROADCAST) {
+      int rval;
+      if (setsockopt(iod->sd, SOL_SOCKET, SO_BROADCAST, (void*)&rval, 
sizeof(int)) == -1) {
+        if (ms->tracelevel > 0)
+          nsock_trace(ms, "Setting of SO_BROADCAST failed (IOD #%li) 
EID %li", iod->id, nse->id);
+      }
+    }
+
     if (connect(iod->sd, (struct sockaddr *) ss, sslen) == -1) {
       int err = socket_errno();


I'd like to make it part of the official distribution, but I know I'm 
missing some critical pieces:

1. I don't think this supports IPv6
2. It will probably do the same thing for TCP, which may break or not 
work as expected
3. I don't have a good test suite to make sure I didn't break anything
4. I only tested on Ubuntu 10.04 with g++ 4.4.3

Any hints as to what my next step would be?

Thanks,
Dan

On 05/11/2010 03:31 PM, Ron wrote:
> I believe what you need to do is find out where it calls Socket() and add a call to Setsockopt() with SO_BROADCAST set 
> to 1.
>
> Search udp.c in my nbtool codebase for 'SO_BROADCAST':
> http://svn.skullsecurity.org:81/ron/security/nbtool/udp.c
>
> To see an example.
>
> Hope that helps!
>
> On Tue, 11 May 2010 15:00:22 -0500 Daniel Miller
> <bonsaiviking () gmail com>  wrote:
>    
> > I would like to use ncat in UDP mode to send broadcast datagrams, but
> > I get "permission denied" errors, even running as root. I understand
> > that there are differences in how to call the underlying system calls
> > when connecting to broadcast, and I'm willing to attempt a patch, but
> > I don't know where to start. Could someone give me a quick pointer to
> > the files I'd have to change to get this to work?
> >
> > doesnotwork# ncat -vvvvv --udp 192.168.1.255 161
> > Ncat: Version 5.30BETA1 ( http://nmap.org/ncat )
> > NSOCK (0.0010s) UDP connection requested to 255.255.255.255:161 (IOD
> > #1) EID 8
> > NSOCK (0.0010s) Callback: CONNECT ERROR [Permission denied (13)] for
> > EID 8 [255.255.255.255:161]
> > Ncat: Permission denied.
> >
> > Thanks for any assistance (or "No, that's a bad idea," as the case
> > may be)
> >
> > Dan
> > _______________________________________________
> > Sent through the nmap-dev mailing list
> > http://cgi.insecure.org/mailman/listinfo/nmap-dev
> > Archived at http://seclists.org/nmap-dev/
> >      
>
>    
>
>
> _______________________________________________
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