On 23/06/2018 09:20, Jan Panteltje wrote:
> On a sunny day (22 Jun 2018 19:49:51 GMT) A. Dumas wrote:
>> Perhaps, but don'€™t fix the ip address on the client, leave it on dhcp
and
>> use your router to assign a fixed address. 99.3% of routers currently on
>> the market can do that.
>
> For some, that is possibly the best solution, yes,
> I have a bunch of computers, sensors, including some raspis, on the LAN.
> The LAN is on 24/7 while the cable modem ('router') is not.

I guess that can be a valid reason. For most people the LAN would
crumble anyway when the modem/router shuts down, I think (direct cables
to modem/router, wifi from modem/router).

> [...]
> There are other reasons for fixed IP addresses too,
> some are hard-coded in the sensors (internet of things)
> and can only be changed via some serial config program, UDP based sensors.
> If you let a router assign the addresses then chances are for a conflict.

Ah that's tricky. What I would do is make sure the DHCP range of my
modem/router lies outside the range used by the sensors.

> Fixed IP address are also much more convenient in testing and debugging.

Well, that's just it. Using fixed IPs depends on good administration or
perfect memory. Apparently you have either or both, so it works for you!

> And also in the router (cable modem in my case) port forwarding is specified,
> for example port 80 to the web server raspi, to some other system for ssh,
etc etc.
> and that needs a fixed address specified.
> And then there is MAC based filtering only allowing some MACs on the Wifi.

Those things also work perfectly well with fixed addresses assigned by
DHCP. Maybe we misunderstood each other? Because I didn't mean
completely free DHCP, but fixing the client address in the DHCP server
aka. the modem/router, letting the DHCP server always assign a certain
address to a certain host using the client's MAC address, or even their
mDNS/bonjour/zeroconf name but that mostly turns out evil. And add a
free DHCP range for devices that don't need a fixed address, e.g. your
phone. All the modem/routers I used in the last 10(?) years could do
this. That way you are guaranteed of:
- no conflicts
- a one-time setup
- a central administration
Now you only have to know the device's name. And yeah, your first
argument probably stands, for you.

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