iptables: Add IPv4/6 IPcomp match support

This patch enables user to set iptables ACTIONs for IPcomp
flow specified by its SPI value.

For example:
iptables  -A OUTPUT -p 108 -m ipcomp --ipcompspi 0x12 -j DROP
ip6tables -A OUTPUT -p 108 -m ipcomp --ipcompspi 0x12 -j DROP

IPcomp packet with spi as 0x12 will be dropped.

Signed-off-by: Fan Du <fan.du@windriver.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
3 files changed