Can a server's eth & wifi share the same IP address?

2026-06-04 16:58 UTC

I’m running Linux Mint on a home server that happens to run pihole. Since it’s both a dhcp and dns server for my network, it has a static ip address. It has an ethernet connection as well as wifi and it’s always been my understanding that you can’t have two network interfaces sharing the same IP address, so I’ve been looking into ways to have one network adapter enabled and the other disabled and then if the network connection of the active device is lost, the other re-enables with the same IP address and disables the other device. This mostly work. However while debugging one bit of software that seems to have a problem with me disabling my wifi adapter, I inadvertently enabled both the eth and wifi connections while each have the same, manually assigned ip address and everything so far just seems to work. I didn’t think this was possible and I’m wondering, should I expect problems? I can connect to the machine remotely fine, pihole and dvr services installed on the box work. Is there any reason to believe this won’t work?

Replies (4)

@moonpiedumplings@programming.dev 2026-06-04 17:00

Yes wiki.archlinux.org/title/Wireless_bonding

Open ##3100804
@atk007@lemmy.world 2026-06-04 18:20

I don’t know how it’s working for you because I just tried on my PC and got an IP address conflict on my router.

Open ##3102194
@pelya@lemmy.world 2026-06-04 19:15

It’s perfectly possible on Linux to have several network adapters with the same IP address, or several default routes. Most server applications will listen to 0.0.0.0 address, which means all network interfaces. Any incoming TCP connection will remember it’s network interface, and the server will send responses to the same interface. This will not work for UDP connections, and for outgoing TCP connections - they will always choose the network interface with the lowest metric, which you can print with ip r command.

Open ##3102921
@daf@lemmy.world 2026-06-05 08:02

What you seem to want is an active-backup bond, I have all my homelab servers with it so they can fail over when the core switch goes down for maintenance. Proxmox provided an easy UI to setup but it can be done with any Linux distro. docs.kernel.org/networking/bonding.html

Open ##3116182