/etc/bindresvport.blacklist is in libc-bin 2.15-0ubuntu10.18.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14  | #
# This file contains a list of port numbers between 600 and 1024,
# which should not be used by bindresvport. bindresvport is mostly
# called by RPC services. This mostly solves the problem, that a
# RPC service uses a well known port of another service.
#
631	# cups
636	# ldaps
774	# rpasswd
783	# spamd
873	# rsync
921	# lwresd
993	# imaps
995	# pops
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