shorewall_code/Shorewall/known_problems.txt

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

2)  A harmless 'unitialized variable' diagnostic is issued by the 
    compiler when it is displaying the capabilities.

    Corrected in Shorewall 4.4.21.

3)  As the result of a typo, an orphan filter chain named FORWAR can
    be created under rare circumstances. This chain is deleted by
    OPTIMIZE level 4.

    Corrected in Shorewall 4.4.21.

4)  The SNAT options --persistent and --randomize (/etc/shorewall/masq)
    generate invalid iptables input.

    Corrected in Shorewall 4.4.21.

5)  The LOGMARK log level was generated invalid iptables  input making
    it unusable.

    Corrected in Shorewall 4.4.21.

6)  Under rare conditions, long port lists (>15 ports) can result in
    the following failure when optimization level 4 is enabled.

       Use of uninitialized value in numeric gt (>) 
       at /usr/share/shorewall/Shorewall/Chains.pm line 1264.

       ERROR: Internal error in
       Shorewall::Chains::decrement_reference_count at
       /usr/share/shorewall/Shorewall/Chains.pm line 1264