Various types of translation are possible with pf:
binat blah-blah-blah
nat blah-blah-blah
rdr The packet is redirected to another destination and possibly a
different port. rdr rules can optionally specify port ranges
instead of single ports. rdr ... port 2000:2999 -> ... port 4000
redirects ports 2000 to 2999 (inclusive) to port 4000. rdr ...
port 2000:2999 -> ... port 4000:* redirects port 2000 to 4000, 2001
to 4001, ..., 2999 to 4999.