Index: share/man/man4/inet.4
===================================================================
--- share/man/man4/inet.4
+++ share/man/man4/inet.4
@@ -284,6 +284,16 @@
 in the reassembly queue for a packet.
 0 means that the host will not accept any fragmented packets for the VNET.
 This is a per-VNET limit.
+.It Va ip.allow_net0
+Boolean: allow experimental use of addresses in 0.0.0.0/8 as endpoints,
+and allow forwarding of packets with these addresses.
+.It Va ip.allow_net240
+Boolean: allow experimental use of addresses in 240.0.0.0/4 as endpoints,
+and allow forwarding of packets with these addresses.
+.It Va ip.loopback_prefix
+Integer: prefix length of the address space reserved for loopback purposes.
+The default is 8, meaning that 127.0.0.0/8 is reserved for loopback,
+and cannot be sent, received, or forwarded on a non-loopback interface.
 .El
 .Sh SEE ALSO
 .Xr ioctl 2 ,