-A INPUT -p tcp -m tcp --tcp-flags ACK ACK -j ACCEPT
> /sbin/iptables -nL
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 255
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:53
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp state RELATED,ESTABLISHED
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp flags:0x10/0x10
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination