/etc/ipsec.d/policies/block is in libreswan 3.23-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | # This file defines the set of CIDRs (network/mask-length) to which
# communication should never be allowed. One IPv4 or IPv6 CIDR per line.
|