This patch adds support for L3/L4 filtering using iptables. This adds
support for 'tcp', 'udp', 'icmp', 'igmp', 'sctp'
etc. filtering.
As mentioned in the introduction, a .c file provided by this patch
is #include'd into a .c file. This will need work, but should be alright
for review.
Signed-off-by: Stefan Berger <stefanb(a)us.ibm.com>