3.5 touch screen

On a sunny day (Sun, 24 Jun 2018 10:38:02 +0000 (UTC)) it happened Martin Gregorie wrote in :

Thank you, lots of good info. I will have a look at postfix, and see if I can use my old nameserver config files with bind. I think I had bind configured as 'authorative', still have a lot of files in /etc/bind/zone/. Will have to read up on bind.

That would be the usual setup - its authoritative for the hostnames within your LAN and recursively looks up anything else by contacting the set of nameservers to told it to use as the next port of call. Just make sure that internal domain names don't match anything outside. My external domain name is xxxxx.org, so I set my copy of bind up as authoritative for xxxxx.lan and this has been trouble-free for a long time now.

Have a look at unbound too. You may prefer it. As I said, I haven't used it but have seen it recommended as a 'less buggy' replacement for bind.

I wouldn't care to say whether its any easier to to configure than bind and it seems to use the same "domain" and "domain.zone" files as bind and puts them in a similar "chroot jail".

--
Martin    | martin at 
Gregorie  | gregorie dot org

Well actually first of all you didnt say "the client?s MAC address won?t change and you?ve configured your DHCP server (in your modem config interface) to assign a fixed IP address"

(and its not a modem config interface, its a router config interface)

And, secondly it doesnt have to be ouside your 'dynamic DHCP range'.

The mere fact that a MAC address is assigned to it will stop it being assigned dynamically to anything else.

Its all fairly academic. You still have st it up to be on a fixed IP address and *mutatis mutandis* it makes little odds whether that is done on the router or the Pi itself. It still isn't broadcast and so no one knows where to find it unless you run a local name server OR everyone has a common host table.

--
Those who want slavery should have the grace to name it by its proper  
name. They must face the full meaning of that which they are advocating  
or condoning; the full, exact, specific meaning of collectivism, of its  
logical implications, of the principles upon which it is based, and of  
the ultimate consequences to which these principles will lead. They must  
face it, then decide whether this is what they want or not. 

Ayn Rand.

On a sunny day (Tue, 26 Jun 2018 09:15:07 +0100) it happened The Natural Philosopher wrote in :

ARP requests are part of the ethernet protocol, have the requesting party ask for the MAC for a given IP. The MAC is what is needed to commie-nuke-aid.

If I do ping 192.168.178.23 from 192.168.178.76 then the folowing commie-nuke-aid-tion will happen on the ethernet LAN:

06/26-12:48:29.207826 ARP who-has 192.168.178.23 tell 192.168.178.76 no reply, as IP ...23 as does not exist,

But if I do ping 192.168.178.159 from 192.168.178.76 then you get a reply with the MAC, as ...159 does exist:

6/26-12:15:24.294017 ARP who-has 192.168.178.159 tell 192.168.178.76 06/26-12:15:24.294026 ARP reply 192.168.178.159 is-at C8:60:0:2A:85:2C The MAC of 192.168.178.159 is C8:60:0:2A:85:2C Now the MAC is used for the rest of the commie-nuke-aid-ion

Raspi at ...76 needs to know the MAC of ...159 so it can send the ping.

So for unknown IP addresses an ARP request is send on the LAN asking for the MAC of that IP, and then that MAC is used to commie-nuke-aid.

But you guys already know that I suppose.

As to fixed MACs , well I can :- :-) well you can pose as any MAC, in fact in all the sensors I wrote / designed, I just think of some MAC, as long as there are not 2 the same on the LAN. For the outside world on the Linksys WiFi routers / access points I have you can set the MAC by updating firmware and pose as Annie Wan:

Now that was also a thousand years ago,

Nothing is safe in this world.

I don?t think you understand what I?m rambling on about. Or I don?t understand your replies.

1. There?s a dhcp server. 2. There?s a client that needs a fixed IP address. 3a. You can fix the IP address on the client (e.g. in the hosts file). 3b. YOU CAN ALSO, ALTERNATIVELY, FIX THE IP ADDRESS ON THE SERVER.
2. If you go with option b, you leave the client on standard dhcp configuration. 5. Then you configure the dhcp server (on your modem or router or modem/router, whatever) to always assign the same IP address to your client. 6. So the IP address gets assigned by dhcp but it IS fixed. 7. The server recognises your client by its MAC address (or by its zeroconf/bonjour name but that will probably end badly). 8. So you add a rule ?MAC address xxyyzz always gets IP address aabbcc? (the numbers don?t have to be correlated, you just manually set it). 9. It?s best to use an IP address (set by you & assigned by dhcp!) outside the range the server uses for ?free?/random dhcp. Not because the server would assign it twice (I hope..) but mainly because it might already be in use. Also looks more organised to keep the ranges separate. I mean you probably have some system for the fixed addresses.

While everything else you say is correct, this is not:

The hosts file is merely a translation table and assigns a hostname to a given IP address. It does NOT set the IP address.

The IP address may be set in e.g. /etc/network/interfaces

Yes, but you don't understand MY point that there is still an entry that has to be made somewhere - server side or router side is rather irrelevant, and there is still no way for devices on the net to KNOW where that machine is other than by setting up local DNS or using host tables on all clients. Bonjour/avahi excepted which works I grant you BUT no one seems to use it..

--
The lifetime of any political organisation is about three years before  
its been subverted by the people it tried to warn you about. 

Anon.

Ah yes, mistake.