Local nat loopback

natloopback.sh

#!/usr/bin/env bash
#Set this to the address to rewrite to:
NewAddress=192.168.0.127

#This pulls the ip from ipify.org:
CurrentAddress=$(wget -qO- https://api.ipify.org)

#Initialize a empty variable containing the lines to delete
lines=""

#Iterate over the iptables result(at end of the loop)
while read -r line ; do
    #Search for the NatLoopback comment
    if [[ $line == *"/* NatLoopback */"* ]]; then
        #If $lines is empty, don't preprend a space
        if [[ $lines == "" ]]; then
            lines="${line%% *}"
        #Else, pre-pend the line (In a reverse array fashion)
        else
            lines="${line%% *} $lines"
        fi
    fi
done <<< $(iptables -t nat -L --line-numbers)

#Iterate over each line number in $lines
for line in $lines; do
    #Delete that line
    iptables -t nat -D OUTPUT $line
done

#Add the new IP forward into iptables
iptables -t nat -A OUTPUT -p tcp -d $CurrentAddress -j DNAT --to-destination $NewAddress -m comment --comment "NatLoopback"