${IPTABLES} -N tcpchk
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL ACK -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL ACK -m state --state NEW,RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL PSH,ACK -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL PSH,ACK -m state --state NEW -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL PSH,ACK -m state --state RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL NONE -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL ALL -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags RST,FIN RST,FIN -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags SYN,URG SYN,URG -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN,PSH -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN,ACK,PSH -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ACK,FIN FIN -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ACK,PSH PSH -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ACK,URG URG -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL RST -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL RST -m state --state NEW,RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags SYN,ACK NONE -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN -m state --state NEW -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags SYN,ACK NONE -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN -m state --state NEW -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN -m state --state RELATED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN -m state --state ESTABLISHED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN,ACK -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL SYN,ACK -m state --state NEW,RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL FIN,ACK -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL FIN,ACK -m state --state NEW,RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL RST,ACK -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL RST,ACK -m state --state NEW -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL RST,ACK -m state --state RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL ACK,PSH,RST -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL ACK,PSH,RST -m state --state NEW,RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL FIN,PSH,ACK -m state --state ESTABLISHED -j RETURN
${IPTABLES} -A tcpchk -p tcp --tcp-flags ALL FIN,PSH,ACK -m state --state NEW,RELATED -j DROP
${IPTABLES} -A tcpchk -p tcp -m state --state INVALID -j DROP