[gentoo-user] Re: [OT] network discovery tools

[Harry Putnam <reader@newsguy.com>]

Grant Edwards <grant.b.edwards@gmail.com> writes:

[...]

>> But when you do it that way, and say want to VNC or ssh or the like to
>> something connected by a dhcp serving WAP then how do you find the
>> address?
>
> The best thing to do is to use a DHCP server and DNS server that are
> "connected" somehow.  Then hostnames "just work".  Or you can
> statically assign IP addresses in the DHCP server so that DHCP clients
> always get hard-wired IP addresses that match up with the /etc/hosts
> file on the DNS server.
>
> I use OpenWRT for WAP, DNS, and DHCP, and it all pretty much "just
> works".  When a DHCP client is assigned an IP address, the DNS server
> knows about it and you can access it by it's hostname just the way you
> would with a static setup.
>
> For various reasons, I assign static IP addresses to a number of
> devices, but I do it via the DHCP server's configuration, not by
> configuring each individual device.

That sounds like a good plan... and worth some thought.  However I was
only asking to find IPs on the home lan after the fact.  Not the
general question of how to setup the lan (though I welcome the ideas
you present).

I seem to have latched onto a tool by a bit more googling, and getting
lucky, called netdiscover that is in portage now.

Just one simple command found all machines active on the home lan
including those with DHCP served addresses:

    netdiscover -i eth0 <ENTER>

Oddly a similar command but aimed at a range misses a few:

    netdiscover -i eth0 -r 192.168.0.0/24 <ENTER>

I guess the tool may use some heuristics if you give it less info.

And for one reason or another a plain `arp' command misses several of
those discovered with `netdiscover -i eth0'

So I found what I needed... thanks.