why- Open BSD .rocks

relayd(8) (∞)

The relayd daemon relays and dynamically redirects incoming connections to a target host. It is mainly used as a load-balancer, an application layer gateway, or a transparent proxy.

The daemon can monitor groups of hosts for availability. This is determined by checking for a specific service common to a host group. When availability is confirmed, layer 3 and/or layer 7 forwarding services are set up by relayd.

ext_addr="192.168.1.1"
table <webhosts> { $webhost1 $webhost2 }
relay www {
        listen on $ext_addr port http
        forward to <webhosts> port http loadbalance check http "/" code 200
}

Details: