DHCP

daphil · 10-03-2023 2:09pm #1

HI,

I have an Octagon (SF8008) and Zgemma (H7S) boxes.

and have always used DHCP, i.e. let the network give the I.P. address.

The problem is that the IP on the boxes change regularly.

Is there any drawback to ignoring DHCP and setting the address on the boxes manually ?

Thanks.

swoofer · 10-03-2023 3:49pm

Believe it or not you should always turn off DHCP once the box has been allocated an IP and now you know the reason why!! So just go back enter network say no to DHCP and retstart network, do a test and save. Write down IP and now you can use it all over the place.

daphil · 10-03-2023 3:52pm

https://www.boards.ie/discussion/comment/120341028#Comment_120341028

Thanks for that, I was not sure if it was ok to do.

Gerry Wicklow · 10-03-2023 3:55pm

By setting a fixed address you will always know the settings to access the web interface (WEBIF) control panel of the box. You can even bookmark it for future reference if you want to check timers or EPG or whatever.

daphil · 10-03-2023 4:14pm

https://www.boards.ie/discussion/comment/120341062#Comment_120341062

Thanks lads, it makes life a bit easier. I thought I heard somewhere, (sometime), that there might be security implications.

Thanks

niallb · 10-03-2023 4:19pm

This might work fine until your router decides to give that IP address out to another device.

It's also likely to fail if you change ISP down the line and might have forgotten what you did.

Smart routers may notice the address is already in use and skip it, but many ISPs provide the cheapest device they could find in bulk anywhere in the world the week they went looking.

If you feel up to logging in to the router you can get the best of both worlds. Look for words like DHCP, Static, Lease, Reservations and set the address lease on your zgemma and octagon to be permanent. That way you can leave them set to DHCP, but they will both still get the same addresses every time. You can do the same for many other things on your network if it suits you too once you're in there.

L1011 · 12-03-2023 8:55pm

https://www.boards.ie/discussion/comment/120341188#Comment_120341188

The race to the bottom on routers actually means more and more of them will be running the same open source DHCP server inside rather than having a custom written one and I'd expect that to be more reliable! Detecting an existing IP and not offering it is fairly default in that software now.

The not at all cheap Farrallon routers Eircom used to ship had a custom DHCP system that would only send a partial offer on lease expiry for instance; knocking a lot of machines offline if they weren't expecting that.

Supercell · 15-03-2023 11:59am

The router should store that address in its mac address table, and not give out the IP at least as long as its been powered up more than a few seconds.

Schorpio · 15-03-2023 1:05pm

You're right, it should. The key word being 'should'!

My golden rule for networking is - if I can take any decisions (or potentially unpredictable behavior) away from the route, I will.

Say, if your network addresses are 192.168.0.X (with the router being at 192.168.0.1), I'll set the DHCP pool to be 192.168.0.10 to 192.168.0.254. That leaves me with 8 addresses that I can assign for static devices (like an enigma2 box), and I know they will never clash or run in to DHCP-related issues.

Glaceon · 16-03-2023 1:07pm

https://www.boards.ie/discussion/comment/120361238#Comment_120361238

Indeed. Just yesterday I was onsite with a client with a UPS issue. I had to power down everything connected to it in order to resolve the problem. But when I powered it back up, the Windows DHCP server started allocating conflicting IPs to Wi-Fi devices that had been statically assigned to other servers! So I had to go in and exclude them manually.

DHCP

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