add a nat rule of iptables

addnat.sh

#!/bin/bash


pro='tcp'
cntip=$1
cntport=$2
hostip=$3
hostport=$4
sudo iptables -t nat -A PREROUTING  -m $pro -p $pro --dport $hostport -j DNAT --to-destination $cntip:$cntport
sudo iptables -t nat -A POSTROUTING -m $pro -p $pro --dport $cntport -d $cntip -j SNAT --to-source $hostip