[PLUG] Routers again <sigh>

[Larry Brigman]

On 4/13/07, Jason Martin <nsxfreddy at gmail.com> wrote:
> On 4/13/07, Michael Rasmussen <mikeraz at patch.com> wrote:
> >
> > Larry Brigman wrote:
> > > ping -b 192.168.1.0
> > > is a broadcast ping to the network. This should respond back with
> > > everything on the network that understands ping. Lots of duplicates.
> >
> > Not everything.  Some IP stacks, on Windows for example, don't respond to
> > broadcast pings.
>
> Nor should they, given the DDoS amplification potential of broadcast
> pings (Smurf attack).  If you need to diagnose between two devices,
> use a unicast (standard) ping.  If you need to discover devices on a
> subnet, use nmap or some other tool that can automate pinging through
> a list of IP addresses.
>
> Linux allows broadcast ping response to be configured through the
> net.ipv4.icmp_echo_ignore_broadcasts sysctl, or via the equivalent
> /proc/sys/net entry.  The default is to ignore (1).
>

It might be default now but not too many kernel versions ago it was 0
and would respond.
However, most networking equipment and devices like networked
printers/print servers
will respond.  It is a tool. Useful in some situations.