Understanding the IP Pool module

[Бен Томпсон]

Thanks Alan

2013/2/12 Alan DeKok <aland at deployingradius.com>:
> Бен Томпсон wrote:
>> I am hoping to use rlm_ippool and I would like to understand a bit
>> about how it works. Firstly I want to understand the format of the
>> database.
>
>   The best approach is to look at the documentation, followed by the code.

I have had a look at the code and have been able to work out a few
things. I will write my findings here, both for my own reference and
for others who might ask the same questions in the future.

Regarding the "active" flag: as I understand it so far, this is
basically supposed to indicate whether a session (e.g. PPP,) is
currently up and using this address. The theory being that the flag is
set to 1 when the IP is dished out during RADIUS post-auth, and it is
set to 0 when the accounting stop is recieved.

I also figured out that "cli" flag is the Calling-Station-Id and this
is used as an identifier in Multilink PPP sessions. It would appear
that in the old days of bundling together conections with dial up
modems (to get more bandwidth) it was necessary to issue the same
address in mutliple authentication requests.

One thing I still don't understand though is how best to use ippool
for DHCP. I don't understand where and how I should call the module
during a DHCP transaction. For example I can call it during
DHCP-Discover, but it seems that if I call it again during
DHCP-Request I might get different address even when the key is the
same. I will continue to to study the code to see why this happens and
if I figure it out I will report back with my findings.

If anyone else knows the answers, I would be grateful hear from them.