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@us.ibm.com>