phpDHCPAdmin demo

[Jason Gerfen]

Piece of cake. I think I am going to implement this as a feature when
a user sets up a new subnet for the dhcpd service to listen on as well
as gather a list of aliased interfaces/net interfaces installed on the
machine to limit errors and/or prevent configurations that might not
be available for a new subnet.

I do appreciate everyone's input on this.

On Sun, Oct 12, 2008 at 12:59 PM, Tim Peiffer <peiffer at umn.edu> wrote:
> Jason Gerfen wrote:
>>
>> Hmmm, so I guess my next question is, is there a way to calculate what
>> would be valid or what would not be a valid broadcast address based on
>> the subnet declaration?
>>
>> If you have an RFC for this I would definitely like to read it to
>> ensue I get the right value prior to writing out the config file. Just
>> trying to make it as easy as possible to check every possible
>> scenario. Thanks.
>>
>
> Um, Comers TCP/IP section 4.5 would be a good start.  The subnet is the
> logical and of an IP address and a netmask.  The inverse or complement of
> the netmask (host mask)  can be logically or'ed with the subnet to produce
> the subnet broadcast address..
>
> Alternatively:  Cisco IOS in a Nutshell By James Boney
>
> $ip && $netmask = $subnet
> $subnet || ! $netmask
>
> Alternatively if you use perl, 'use Net::Netmask'.
>
> use Net::Netmask;
> $block = new Net::Netmask (network block, netmask)
> $broadcast = $block->broadcast();
>
> Regards,
> Tim Peiffer
> Network Operations Engineer
> Networking and Telecommunications Services
> University of Minnesota
>
>
>> On Sun, Oct 12, 2008 at 11:18 AM, Sten Carlsen <sten at s-carlsen.dk> wrote:
>>
>>>
>>> Almost, broadcast address is always "all-ones" in the host part of the
>>> IP. Should be:
>>>
>>>    option broadcast-address 192.168.173.255;
>>>                                         ^^^
>>>
>>> Hopefully the arrowheads are still under the 255 when this is received
>>> ;-)
>>>
>>> Jason Gerfen wrote:
>>>
>>>>
>>>> On Sun, Oct 12, 2008 at 8:47 AM, Glenn Satchell
>>>> <Glenn.Satchell at uniq.com.au> wrote:
>>>>
>>>>
>>>>>>
>>>>>> Date: Sun, 12 Oct 2008 09:35:50 +0100
>>>>>> To: dhcp-users at isc.org
>>>>>> From: Simon Hobson <dhcp1 at thehobsons.co.uk>
>>>>>> Subject: Re: phpDHCPAdmin demo
>>>>>>
>>>>>> Glenn Satchell wrote:
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> option broadcast-address can be derived from the subnet declaration?
>>>>>>> It is inherited from that scope - and if the two are different, well
>>>>>>> your configuration is not correct.
>>>>>>>
>>>>>>> subnet a.b.c.d netmask e.f.g.h {
>>>>>>>  option broadcast-address e.f.g.h;
>>>>>>> }
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> Must have been a long day for you Glenn :-)
>>>>>>
>>>>>> Yes broadcast address can be derived, but it's more like :
>>>>>>
>>>>>> subnet a.b.c.d netmask e.f.g.h {
>>>>>>  option broadcast-address i.j.k.l;
>>>>>> }
>>>>>>
>>>>>> where i.j.k.l = a.b.c.d OR NOT(e.f.g.h)
>>>>>>
>>>>>> Of course, the option subnet-mask should be the same as in the subnet
>>>>>> declaration.
>>>>>>
>>>>>>
>>>>>
>>>>> It was a long day, but you knew exactly what I meant :)
>>>>>
>>>>>
>>>>>
>>>>
>>>> Like so?
>>>>
>>>> subnet 192.168.173.0 netmask 255.255.255.0 {
>>>>     option domain-name-servers 192.168.173.10, 192.168.173.11;
>>>>     option routers 192.168.173.1;
>>>>     option ip-forwarding on;
>>>>     option broadcast-address 192.168.173.0;
>>>>     option ntp-servers 192.168.173.2;
>>>>     option netbios-name-servers 192.168.173.3;
>>>>     default-lease-time 1800;
>>>>     min-lease-time 30;
>>>>     max-lease-time 3600;
>>>> }
>>>>
>>>> The 'subnet' declaration matches the 'option broadcast-address'
>>>> declaration here and when I tested the new .conf file it worked?
>>>>
>>>> Should I include some error checking to ensure the subnet declaration
>>>> and the broadcast-address (if present) match?
>>>>
>>>> I hope I understood you correctly.
>>>>
>>>>
>>>>
>>>>>
>>>>> regards,
>>>>> -glenn
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>> --
>>> Best regards
>>>
>>> Sten Carlsen
>>>
>>> No improvements come from shouting:
>>>
>>>      "MALE BOVINE MANURE!!!"
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>
>
>



-- 
Jason Gerfen
jason.gerfen at gmail.com

~ tomorrow ain't promised so we live for today