Attention Shorewall-perl users running versions prior to 4.2.6.1:

There is a problem in the code which causes interface options such as
tcpflags and nosmurfs to not be applied to forwarded traffic.

This problem is corrected in Shorewall-perl 4.2.6.1. You are advised to
either upgrade to that version or to apply forward.patch as follows:

patch /usr/share/shorewall-perl/Shorewall/Rules.pm < forward.patch