RPi associating two IPs with its one and only wifi interface

For years my main *86 server would register itself with DHCP first, then manually set its IP address to something else.

In the end I plugged in a screen and used the GUI and net manager to sort it all out, and it stayed sorted out.

The problem is that there have been so many ways to set up IP over the last few years that any online guidance has at best a 25% chance of doing it the way the distro thinks it ought to be done,

Did the Pi itself think that it had two addresses on the WiFi interface or was it your router / dhcp server that had two records?

I am nor sure. I think I could at least ping the DHCP assigned interface.

The router only has DHCP records - statics are not recorded

But its all gone these days...

My point being this is not Pi or wifi specific, it is an issue with network configuration

Where are you finding the two addresses?

What does ip addr show display?

What does rpi-eeprom-config display?

The web suggests some have been shipped with netbook enabled.

Just in case that question was directed at me...

No, the Pi thought two IPs were associated with the one and only wifi card. (In fact, I discovered which device it was by ssh-ing in after nmap told me that it was listening on the sshd port.)

Jim

I have been using the same sort of setup with various computers (all running various Linux distros) for years, and this is a new issue for me.

I don't think it is so much that my networkmanager config is problematic, but that something else sets up an IP address before networkmanager is running. (At least, if the netboot story is accurate.)

Jim

BOOT_UART=0 WAKE_ON_GPIO=1 POWER_OFF_ON_HALT=0

(Nothing there about BOOT_ORDER, altho my Pi5 (not the computer that showed up with two IPs) does have BOOT_ORDER=0xf461. But it would appear I'd need a 0x2 in there fairly early for it to try a netboot.)

Is that in some way that doesn't show up in the output of rpi-eeprom-config?

Thanks.

Jim

Just a note that this itself is not an error; the Pi doesn’t *think* the interface has two IPs, it *knows*, because it was configured that way.

There are legitimate uses for this sort of thing, even though it was not a deliberate setup in your case.

What model of Pi is it?

Elsewhere:

i.e. the interface has two addresses after booting has completed. I would put network boot at the bottom of the list of possible causes. AIUI the kernel starts from a blank slate, it doesn’t inherit interface configuration from the boot loader.

IIRC in my setup I had static setup via a hand edited file somewhere, and it was booting into DHCP before it read that file

It was in fact two IPv4 addresses. One which the Network Manager config file specifies, and the other was some other address which I speculate came from the router's DHCP server.

Jim

RPi 4 (4 GB version). More specifically, /proc/cpuinfo says Raspberry Pi 4 Model B Rev 1.1

The main reason I suggested that was because when I went hunting around the internet, that was the only thing I came across. I'm not stuck on that idea, but so far it is the only suggestion I've seen.

Cheers. Jim

You can check the routers DHCP table and the MAC addresses associated with it.

As I did.

Yes, I have recently been experimenting with IPv6.

IPv6 uses: Static Addresses, Link-Local, DHCPv6, Router Advertisements, and SLAAC. Proving me with multiple, often random, IPv6 addresses. This totally broke my IP rule based routing.

Unlike my Linux machines, My Android devices take a whole IPv6 block (prefix delegation). I think I'll change all my Linux hosts to this too. I quite like the protection of random addresses, but want them constrained to a recognisable range for each host.

Some websites fail, some apt repos fail under IPv6.

IPv6 seems like a world of pain.

OK... If we want to be really careful with our English, I suppose we should say "The Pi associated two IPv4 addresses with the one and only WiFi card."

Not running any AI on my Pi, I don't think it knows or thinks anything. ;-)

Quite true, I have used it once or twice in the past myself. (Why I did it is now lost in the depths of time.)

Jim

My router's DHCP function has a serious case of brain damage. (It is supplied by my ISP and is not easy to avoid using, because of the way they control their fiber optic cable based system.) Right now it thinks the Pi in question is using the "mystery" IPv4 address, and it resolutely declares that the "proper" address is not connected. The Pi itself disagrees.

However, it was worth a look. Maybe. According to the router, the "mystery" address is paired with the wifi card's actual ethernet (MAC) address, whereas the "proper" address is (currently) paired with the same ethernet address, except the last octet is 8C instead of 8D. This makes me think that it is showing "Connected" or "Disconnected" according to the ethernet address which is working, and it is not careful about pairing that with the correct IPv4 address.

Jim

Did someone say "new and improved" ? ;-)

My current ISP is Frontier Fiber, and I have a business account with a static IP address. While they supply a fiber termination unit in my house wiring closet, they also supply a Sagemcom router/WiFi device, which I *must* use because my static IP is the creation of a VPN feature inside the router, for which they do not provide any usable documentation. So I had them bridge that IP to one of the ethernet ports on the Sagemcom device, and then have my own edge router attached to that. I can't turn off the WiFi on the Sagemcom, but I have my own WiFi access point behind my router.

I am not very happy with the arrangement, but my bandwidth is 500 Mbps symmetric, although my (old) edge router is only 10/100 ethernet. But after spending years on a 15Mbps symmetric network, I am happy to get 100/100 that WORKS.

I wonder why you would use an ISP-supplied router -- don’t you get to connect your own?

That’s what I have done, here in 🇳🇿. I have turned off its DHCP function, and run my own DHCP server on a separate Linux box, so that I can more easily keep track of lists of statically-assigned addresses for my trusted machines.