For the test.. i'm just curious, there is no other reason.

However, On the client side, I wrote simple scripts to run the dhclient,
and this script will sequentially run 512 dhclient.(the number 512 is not a
magic value, other values will happen same situation.)

steps of the script:

1. create macvlan interface(It will make different MAC address for clients)

2. run dhclient with macvlan interface

3. get an IP from DHCPv6 server

4. kill the dhclient and remove the macvlan interface

5. back to step 1. and go on.


Results:

After scripts, if the 513th client comes, the server will serve the IP to
the 513th client.  but it is not just lease max + 1 th client getting
this issue, all after the 512th client can get IP from the server.
At this time,  the lease entries are remaining at 512, and all after
clients will not appear in the lease file.



Thanks,
Lin



Geert Stappers <stapp...@stappers.nl> 於 2023年5月23日 週二 下午1:59寫道:

> On Tue, May 23, 2023 at 12:05:08AM +0100, Simon Kelley wrote:
> > On 22/05/2023 12:18, Linyih Teng wrote:
> > > In the manual page is written:
> > > > -X, --dhcp-lease-max=<number>
> > > >        Limits  dnsmasq  to  the  specified  maximum number of DHCP
> > > >        leases. The default is 1000. This limit is to  prevent  DoS
> > > >        attacks from hosts which create thousands of leases and use
> > > >        lots of memory in the dnsmasq process.
> > >
> > > Hello,
> > >
> > > I'm using dnsmasq2.89 and testing the maximum lease count of the DHCPv6
> > > server with the *dhcp-lease-max* option.
> > >
> > > For the testing, I'm using below configuration:
> > >
> > >     *dhcp-lease-max* = 512
> > >     *dhcp-range*=tag:pool0,2022::1,2022::1f:ffff:ffff:fffe,64,120m
> > >     tag-if=set:pool0,tag:intfv0
> > >
> > >
> > > However, when the number of clients reaches the maximum number, the
> > > server still provides IPs to clients. Is this the expected behavior of
> > > DHCPv6?
> > >
> > There's a possible difference between the number of clients and the
> number
> > of DHCP leases, since leases can expire to be deleted by the client.
> >
> > Are you saying that the number of simultaneous DHCP leases increases
> without
> > bound, or that the 513th client gets a lease? Have you checked the
> number of
> > leases in the dnsmasq.leases file?
>
> Original Poster has yet to say what the expected behaviour should be.
>
> Thing I am saying: Why limit dhcp-range by dhcp-lease-max?
>
>
> Regards
> Geert Stappers
> --
> Silence is hard to parse
>
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