iptables 2023 met NAT
teacher@vbox01:~$ cat /etc/iptables/iptables.003.sh
#! /bin/bash
#
# iptables-script
# bvdb ( 25/04/2023 ) version 003 with NAT ROUTING
######################################################
#
# here follows the script ....
# v = verbose, X = flush tables, F = delete non standard chains
# general
iptables -vX
iptables -vF
# nat and masquerading -t refers to table
iptables -vt nat -F
iptables -vt nat -X
# mangling TCP header
iptables -vt mangle -F
iptables -vt mangle -X
# reset policies -P refers to policies
iptables -vP INPUT ACCEPT
iptables -vP OUTPUT ACCEPT
iptables -vP FORWARD ACCEPT
# turn off routing
echo 0 > /proc/sys/net/ipv4/ip_forward
### HERE COMES THE IPTABLES LOGIC (one day, who knows when ?)
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -vt nat -A POSTROUTING -o enp0s3 -j SNAT --to 10.104.111.111
### PRINT iptables configuration
###
#
echo ">>>>> iptables -n -L"
iptables -n -L
echo "--------------"
echo ">>>>> iptables -S"
iptables -S
echo "--------------"
echo ">>>>> iptables -t nat -L"
iptables -t nat -L
echo "--------------"
echo ">>>>> iptables -t mangle -L"
iptables -t mangle -L
echo "--------------"
echo "routing set: " `cat /proc/sys/net/ipv4/ip_forward`
echo "=============="