Keepalived to set up a floating IP between two proxy hosts. The VIP is where the traffic points to, the two hosts act as active/passive HA.
Looking into this a little, it might be what I need. The documentation I’ve found on this says it uses VRRP, which creates a “virtual” IP address; will that be different from the machine’s own IP address? And will an ordinary router be able to forward a port to this kind of virtual IP address without any special configuration?
Yes. Your machines would have one main IP address, and one virtual IP address that would be assigned to either machine depending on the priority or health check status. That IP can be on the same physical interface, or a separate one. It’s very flexible, pretty standard config for high availability setups.
@Decipher0771 @victory Neat, I didn't know keepalived was still active and popular. https://bugs.debian.org/144100