1)  On systems running Upstart, shorewall-init cannot reliably secure
    the firewall before interfaces are brought up.

2)  The 'enable', 'reenable' and 'disable' commands do not work
    correctly in configurations with USE_DEFAULT_RT=No and optional
    providers listed in the DUPLICATE column.

3)  If a masq file with no entries is found by the compiler, then the
    snat file, if any, is ignored.

    Corrected in Shorewall 5.1.5.1.
