iptables -I INPUT -m state --state INVALID -j logblock
iptables -I OUTPUT -m state --state INVALID -j logblock

IN= OUT=eth0 SRC=67.18.*.*DST=140.211.*.* LEN=52 TOS=0x00 PREC=0x00 TTL=64 ID=1362 DF PROTO=TCP SPT=39659 DPT=80 WINDOW=126 RES=0x00 ACK FIN URGP=0

net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.all.rp_filter = 1
net.ipv4.tcp_syncookies = 1
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216
net.ipv4.tcp_no_metrics_save = 1
net.ipv4.tcp_moderate_rcvbuf = 1
net.core.netdev_max_backlog = 2500
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.default.accept_source_route = 0
net.ipv4.conf.default.log_martians = 1
net.ipv4.icmp_echo_ignore_broadcasts = 1
net.ipv4.icmp_ignore_bogus_error_responses = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1