#units=63
units=15

IP4='xxx.xxx.xxx.xxx'
#PSID='6e'
#PSID='110'
PSID=110
LANDEV='br-lan'
WAN6DEV='eth0'
TUNDEV='map-MAP'

iptables -t nat -F PREROUTING
iptables -t nat -F OUTPUT
iptables -t nat -F POSTROUTING

rule=1
while [ $rule -le $units  ] ; do
  mark=`expr $rule + 16`
  pn=`expr $rule - 1`
  portl=`expr $rule \* 4096 + $PSID \* 16`
  portr=`expr $portl + 15`

  echo iptables -t nat -A PREROUTING -p tcp -m statistic --mode nth --every $units --packet $pn -j MARK --set-mark $mark
  iptables -t nat -A PREROUTING -p tcp -m statistic --mode nth --every $units --packet $pn -j MARK --set-mark $mark
  echo iptables -t nat -A OUTPUT -p tcp -m statistic --mode nth --every $units --packet $pn -j MARK --set-mark $mark
  iptables -t nat -A OUTPUT -p tcp -m statistic --mode nth --every $units --packet $pn -j MARK --set-mark $mark

  echo iptables -t nat -A POSTROUTING -p icmp -m connlimit --connlimit-daddr --connlimit-upto 16 --connlimit-mask 0 -o $TUNDEV -j SNAT --to $IP4:$portl-$portr
  iptables -t nat -A POSTROUTING -p icmp -m connlimit --connlimit-daddr --connlimit-upto 16 --connlimit-mask 0 -o $TUNDEV -j SNAT --to $IP4:$portl-$portr
  echo iptables -t nat -A POSTROUTING -p tcp -o $TUNDEV -m mark --mark $mark -j SNAT --to $IP4:$portl-$portr
  iptables -t nat -A POSTROUTING -p tcp -o $TUNDEV -m mark --mark $mark -j SNAT --to $IP4:$portl-$portr
  echo iptables -t nat -A POSTROUTING -p udp -m connlimit --connlimit-daddr --connlimit-upto 16 --connlimit-mask 0 -o $TUNDEV -j SNAT --to $IP4:$portl-$portr
  iptables -t nat -A POSTROUTING -p udp -m connlimit --connlimit-daddr --connlimit-upto 16 --connlimit-mask 0 -o $TUNDEV -j SNAT --to $IP4:$portl-$portr

  rule=`expr $rule + 1`
done