From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Rymes To: development@lists.ipfire.org Subject: Re: [PATCH] bug#10629: Prevent dynamic and fixed leases overlapping Date: Thu, 18 Feb 2021 17:38:08 -0500 Message-ID: In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4111570087007066259==" List-Id: --===============4111570087007066259== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable > On Feb 18, 2021, at 11:23 AM, Bernhard Bitsch wr= ote: >=20 > =EF=BB=BFHi, >=20 >=20 >> Gesendet: Donnerstag, 18. Februar 2021 um 17:05 Uhr >> Von: "Tom Rymes" >> An: "Bernhard Bitsch" >> Cc: development(a)lists.ipfire.org >> Betreff: Re: [PATCH] bug#10629: Prevent dynamic and fixed leases overlappi= ng >>=20 >>=20 >>=20 >>>> On Feb 18, 2021, at 10:29 AM, Bernhard Bitsch = wrote: >>>=20 >>>> Gesendet: Donnerstag, 18. Februar 2021 um 16:18 Uhr >>>> Von: "Michael Tremer" >>>>=20 >>>>>> On 18 Feb 2021, at 14:01, Adolf Belka (ipfire-dev) wrote: >>>>>=20 >>>>> On 18/02/2021 14:06, Michael Tremer wrote: >>>>>=20 >>=20 >> [snip] >>=20 >>>>> The only thing that would be more difficult is if the user expands an e= xisting dynamic range that already overlaps with two fixed leases so that it = now overlaps with four fixed leases. It will be difficult to determine which = were the original existing and which are the new overlapped leases without ha= ving a parameter stored in a file that counts which leases were overlapping w= hen the Core Update upgrade is carried out. That could be done but I think th= e simplest will be that any overlap due to a change in the dynamic range shou= ld just get a warning and not an error. Does that sound okay. >>>>=20 >>>> Oh yeah, difficult question. >>>>=20 >>>> I did not assume that this was very dynamic before. >>>>=20 >>>> Potentially it is a good solution to simply split the pool in the backen= d and not tell the user. So in the configuration instead of writing 192.168.0= .100-192.168.0.200, you would add a break for every static lease: >>>>=20 >>>> * 192.168.0.100 - 192.168.0.105 >>>> * 192.168.0.107 - 192.168.0.112 >>>> * 192.168.0.114 - 192.168.0.200 >>>>=20 >>>> In this example, 192.168.0.106 and 192.168.0.113 would be static leases. >>>>=20 >>>> That would make the solution transparent for the user, but a pain for th= e developer. >>>>=20 >>>=20 >>> I do not think, that pools are right tool for the problem. Address pools = are used with a slight different semantic in dhcpd. This difference may incre= ase in future. >>> Not mentioning the effort to split the set of possible IP addresses and t= o verify this process. >>=20 >> [snip] >>=20 >> This was my original suggestion for how to handle this, and at the time I = opened the big, it was my understanding that this was the proper way to handl= e this. Others have arrived at a different conclusion, and to me it seems lik= e more of a style thing than a functional thing. >>=20 >> Using multiple range definitions to exclude fixed addresses also has the b= enefit of allowing a user to keep a host=E2=80=99s address the same, which ca= n be very helpful in instances where a lot of work may be required to change = a host=E2=80=99s IP. >>=20 >> Tom >=20 > In instances where it is a big effort to change a host's IP, it is also the= (same?) effort to set this IP. Therefore it is possible to define this IP as= a fixed lease for this (known!) device. >=20 > Bernhard Bernhard: not really. The way I see it is that someone sets up a server, then= assigns it a reserved/fixed address that overlaps with the dynamic range. Ye= ars pass. I inherit this network and I have to move the IP out of the dynamic= range, but I=E2=80=99m going to have to maniacally change various clients, e= tc. It=E2=80=99s not the end of the world, but the currently proposed strategy re= quires me to move that IP, whereas the option of multiple range definitions p= er subnet ( excluding the reserved addresses) allows me to keep it for now an= d move it when. I able to properly plan to do so. Tom --===============4111570087007066259==--