|Building The Network You Need With PF, The OpenBSD Packet Filter: BSDCan 2016, Ottawa, Canada, June 8th 2016|
In addition to smart rdr (redirect), relayd offers layer 7 (application layer) proxying via the relay keyword.
Relays offer a number of possibilities:
filtering (match, pass, block etc) using a PF-inspired syntax
TLS processing (requires private key and certificate in specific locations, see the relayd.conf man page), including tweaking tls (previously ssl) protocol options
TCP parameter tweaks
... in addition to forwarding and load balancing