Enable MDNS on a FreeNAS/BSD jail. That will allow a Avahi name resolution of the jail in the local network.

mdns.sh

#!/bin/sh
# This script is to be executed on the FreeNAS/BSD host itself (and not inside the jail)
# Warning: The proper space-delimited interface(s) must be passed in mdnsd_flags or it will not work.
# usage : ./mnds.sh <jail name or jid>

pkg -j ${1} install --yes openmdns
sysrc -j ${1} mdnsd_enable=yes
#IFACE=$(jexec -l  ${1} ifconfig | grep epair | head -n 1 | cut -f1 -d:) # This assumes different networking than I use.
IFACE=$(ifconfig -l -u | sed -e 's/[[:space:]]lo.[[:space:]]*//g')  # Why use 3 pipes when the base command will format it for you?
sysrc -j ${1} mdnsd_flags="${IFACE}"
service -j ${1} mdnsd start