FreeBSD has the sysctls you are looking for to control the reserved port range, allowing unprivileged users to bind (curious that Linux doesn't):

    $ sudo sysctl net.inet.ip.portrange.reservedlow=10
    net.inet.ip.portrange.reservedlow: 0 -> 10
    $ nc -vvl 1
    ^C
    $ sudo sysctl net.inet.ip.portrange.reservedlow=0 
    net.inet.ip.portrange.reservedlow: 10 -> 0
    $ nc -vvl 1
    nc: Permission denied