Add some notes about SELinux

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
iptables: drop unsollocited multicast and broadcast and accept FIN+ACK invalid state output

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>
Add debian-dev documentation

Signed-off-by: Nicolas Iooss <nicolas.iooss_git@polytechnique.org>