How to get ip address automatically from different dhcp server

[dave jones]

Hi Christopher,

Thanks for your solution. It does help a lot, but there's one problem.
For example, DHCP server is not started for some reason and my computer's
ethernet cable is plugged. Once dhcp server started, I can't get the IP unless
I unplug and then plug the ethernet cable. Do you know how to solve
this issue? Thank you.

Regards,
Dave.

On Thu, Jul 28, 2011 at 4:30 AM, Christopher J. Ruwe  wrote:
> On Wed, 27 Jul 2011 10:49:42 +0800
> dave jones <s.dave.jones at gmail.com> wrote:
>
>> Hi,
>>
>> I cat get an IP address from dhcp server by adding the line
>> in /etc/rc.conf:
>>
>> ifconfig_em0="DHCP"
>>
>> If I move my laptop to another place, I have to manually run
>> "dhclient em0" to get an IP. Otherwise, it won't get an IP
>> automatically.
>>
>> My question is it's possible to get ip address automatically from
>> different dhcp server? thanks.
>>
>> Regards,
>> Dave.
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>
> Have a look at /etc/devd.conf. Mine include a portion
>
> #
> # Try to start dhclient on Ethernet like interfaces when the link comes
> # up.  Only devices that are configured to support DHCP will actually
> # run it.  No link down rule exists because dhclient automaticly exits
> # when the link goes down.
> #
> notify 0 {
>        match "system"          "IFNET";
>        match "type"            "LINK_UP";
>        media-type              "ethernet";
>        action "/etc/rc.d/dhclient quietstart $subsystem";
> };
> #
> notify 0 {
>        match "system"          "IFNET";
>        match "type"            "LINK_DOWN";
>        media-type              "ethernet";
>        action "/etc/rc.d/dhclient quietstop $subsystem ; ifconfig $subsystem inet 0.0.0.0";
> };
>
> I am under the impression that this rule does what you want to do.
>
> Cheers,
> --
> Christopher J. Ruwe
> TZ GMT + 2
>