[Malvern] DHCP versus static.

[Richard Forster]

> On Mon, Feb 27, 2006 at 11:41:41AM +0000, Geoff Bagley wrote:
> 
>>I am still trying to get a better understanding of Ethernet.
>>

>>Do you guys  prefer to use Static IP addresses on your LAN,  or do you 
>>prefer DHCP ?

I have DHCP. But then I have the simplest network possible (PC and 
router on a /30) and clicking one checkbox to get my PC to talk DHCP was 
the setup that required minimal effort.


> Do you have a dynamic network?  If not, there's no need for DHCP.  If you're
> gonna ssh into other boxes or mount their disks then it's a pain if you've
> got DHCP running on the remote ends, you don't know where they are unless
> you're running a local DNS.  If your DHCP always gives the same addresses to
> the same machines then it's not dynamic either and it's just a stupid way of
> achieving a static network setup.

Simple and stupid are not quite the same ;-)

Geoff, you probably don't need it. In fact, if you are more interested 
in what you do with connectivity on your LAN (local apt caches for 
example so you only download Debian updates once) then just code static 
addresses. If you are more interested in getting it to all auto 
configure and be expandable (in theory) then by all means have a play 
and get them all to use DHCP.

You could also think about setting up an IPv6 network. For kicks.


>>Can you read out the MAC number of  another host (that being invariable) ? 
>>A bit like pinging, but more specific and informative.
Many ways.

arp will get you started
nmap is awesome (try nmapfe for the GUI). Type 192.168.0.* (or your 
equivalent) into the target(s) section and click 'scan'. nmap will tell 
you what OS your machines are running, who made your network card and 
ADSL router etc, which ports are open etc etc etc.
ethereal, as Chris mentioned is also awesome. You can filter by source, 
destination, traffic type etc etc. Also draws cool graphs. Very groovy 
when run on a machine plugged into a switchport set to 'monitor' mode.

While you're playing, lookup how you can change your MAC address with 
ifconfig.

> You mean do an equivalent to ping at the eth level instead of at IP level? 
> Probably.  Have you looked at things like tcpdump and ethereal to see what's
> happening on your network?

I think arping is closest to what Chris thought was probable.


Cheers

Rick