Re: dhc* in NetBSD 7.0

[Roy Marples <roy%marples.name@localhost>]

On 27/03/2013 22:58, Robert Elz wrote:
> Date:        Wed, 27 Mar 2013 17:20:13 +0000
>     From:        Roy Marples <roy%marples.name@localhost>
>     Message-ID:  <d49eb0692754b48421e62b5bfb98658c%mail.marples.name@localhost>
>
>   | dhcpcd has grown into a network manager like application
>
> Yes, I know, that is what I am not sure is a good thing, it really
> should not need to do everything.

Well, it's not a text editor like say emacs for sure :)

It does everything needed to configure network addresses.
It's only a small extension from the basic goal of a DHCP client.

>   | Well I do have to admin that defining how the wired is configured 
> based
>   | on the SSID quite odd.
>
> Perhaps.
>
>   | Can you explain why you do this?
>
> Sure, at work we have a normal kind of network, managed by typical
> network manager types, with dhcp server, firewalls, and all that 
> normal
> stuff - to access it, the only option is to use the dhcp server to
> assign addresses.
>
> On the other hand, my network at home is very transitory, there are 
> no fixed
> systems just a cheap(ish) switch and whatever systems (mostly 
> laptops) happen
> to be there at the time that want to exchange data at a higher rate 
> than
> is available over the wireless net (which is how the world is 
> reached).
> On that net, there's no system suitable to run a dhcp server, so I 
> just
> statically configure addresses (there's plenty of available rfc1918 
> address
> space so every system can have a fixed assigned address).
>
> Then there's just the question of how to decide whether the systems 
> should
> use the dhcp config, or the static one - the one trivially easily 
> visible
> difference is the wireless network name - I know what names exist at 
> work,
> and at home (and a few other places I visit regularly) so I just look 
> to
> see what is there, and from that decide where I am, and then use the
> appropriate configuration.
>
>   | Maybe dhcpcd can make it easier, or it's just outside its scope.
>
> I hope the latter - I was not suggesting that dhcpcd be extended in 
> any
> way for this, I don't need that, what it does now is just fine (in 
> that all
> i need it to do is dhcp when dhcp is required).   if anything, I'd 
> prefer
> that dhcpcd be simplified to keep only the dhcp parts (thou perhaps 
> some
> of the extra is all so bound up in the config that dhcp is going to 
> do
> that for some uses it makes sense to keep it all.)

From dhcpcd.conf(5)
arping address [address]
dhcpcd will arping each address in order before attempting DHCP. If an 
address is found, we will select the replying hardware address as the 
profile, otherwise the ip address. Example:

interface bge0
arping 192.168.0.1

profile 192.168.0.1
static ip_address=192.168.0.10/24


So in this case, as you have no gateway on the LAN you could ping the 
LAN side address of your access point. If that's not connected to the 
switch, so that the LAN is 100% seperated from the wireless you could 
reduce the DHCP timeout of 30 seconds to something more manageable and 
use a fallback profile if no DHCP response like so:

timeout 6
interface bge0
fallback 192.168.0.1

profile 192.168.0.1
static ip_address=192.168.0.10/24

The other option would be to scrap the static address assignment and 
use the ZeroConf system of working.

If that's not acceptable then I could create a new config toggle in a 
future version like so:

ssid HomeOfKre
force_profile bge0 192.168.0.1

Should be possible to write that just a few lines. Let me know what 
works for you :)

Thanks

Roy