internal representation scribble sheet

iptables:
flags * sysctl, oob tuning
filter * filter
mangle * mangle
nat * nat

openbsd pf
flags * set, sysctl
filter * block, pass, antispoof
mangle * scrub
nat * nat, rdr, binat

ipfilter http://www.obfuscation.org/ipf/ipf-howto.txt
http://cheops.anu.edu.au/~avalon/ip-filter.html

flags * no 
filter * block, pass
mangle * no
nat * map, rdr

cisco http://www.opennet.ru/soft/cisco-configuration.html
http://bio3d.colorado.edu/~tor/sadocs/tcpip/firewall.html
flags: no
filter: access
mangle: no
nat: no

ipchains:
flags: sysctl, oob
filter: yes
mangle: no?
nat: yes

