ddos: set net.ipv4.tcp_syncookies to 1

set tcp_syncookies to 1 alone with iptables
SYNPROXY module reduce latency, this improves
situation when XDP acceleration is not enabled
and just let iptables SYNPROXY handles SYN flood
attack, see [0]

[0]: https://bugzilla.kernel.org/show_bug.cgi?id=219500

Signed-off-by: Vincent Li <vincent.mc.li@gmail.com>

src/initscripts/system/ddos

@@ -53,7 +53,7 @@ get_ports () {
 }
 
 load_syncookie () {
-	sysctl -w net.ipv4.tcp_syncookies=2
+	sysctl -w net.ipv4.tcp_syncookies=1
 	sysctl -w net.ipv4.tcp_timestamps=1
 	sysctl -w net.netfilter.nf_conntrack_tcp_loose=0
 	/usr/sbin/xdp-loader status red0 | grep 'syncookie_xdp'