IPTABLE 對付(減輕) DDOS 的設定

# Make sure NEW tcp connections are SYN packets
iptables -N syn-flood
iptables -A INPUT -p tcp --syn -j syn-flood
iptables -A syn-flood -m limit --limit 1/s --limit-burst 4 -j RETURN
iptables -A syn-flood -j DROP
iptables -A INPUT -i eth0 -p tcp ! --syn -m state --state NEW -j DROP

#SYN_RECV
echo "1" > /proc/sys/net/ipv4/tcp_syncookies
echo "10" > /proc/sys/net/ipv4/tcp_fin_timeout
echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_all
echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
echo "5000" > /proc/sys/net/ipv4/tcp_max_syn_backlog
#TIME_WAIT
echo "180000" > /proc/sys/net/ipv4/tcp_max_tw_buckets
echo "1" > /proc/sys/net/ipv4/tcp_rfc1337
echo "1" > /proc/sys/net/ipv4/tcp_tw_recycle
echo "1" > /proc/sys/net/ipv4/tcp_tw_reuse
echo "5" > /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_time_wait
echo "10" > /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_syn_recv
echo "10" > /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_syn_sent