Network address translation (NAT) is a method of remapping an IP address space into another by modifying network address information in the IP header of packets while they are in transit across a traffic routing device. The technique was originally used to avoid the need to assign a new address to every host when a network was moved, or when the upstream Internet service provider was replaced

linux - iptables: change local source address if $ iptables -t nat -A POSTROUTING --destination 10.0.0.1/32 -j SNAT --to-source 10.0.0.160 2. Using a static route. Alternatively, instead of an iptables rule, add a static route for the destination host to the routing table, using the following syntax: $ ip route add /32 via src Quick-Tip: Linux NAT in Four Steps using iptables # /sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # /sbin/iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT # /sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT You should now be NATing. You can test this by pinging an … networking - What is MASQUERADE in the context of iptables Note that this is not limited to the internet network masquerade/NAT can be used to route traffic from one network to an other let say 10.0.0.0/24 and 192.168.0.0/24 . Iptables masquerade rule can be replaced with SNAT rule. iptables -t nat -A POSTROUTING -o eth2 -s 10.0.0.0/24 -j MASQUERADE =

Chapter 14. iptables firewall

# /sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # /sbin/iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT # /sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT You should now be NATing. You can test this by pinging an external address from one of your internal hosts. Apr 30, 2003 · iptables -A INPUT -p tcp -s 192.168.1.0/24 --dport 21 -j ACCEPT In this case the rule only allows FTP if the source is 192.168.1.0/24 and it is heading to port 21 on my linux box. That could be modified to iptables -A INPUT -p tcp -s 192.168.1.0/24 --sport 21 -j ACCEPT MASQUERADE is an iptables target that can be used instead of SNAT target (source NAT) when external ip of the inet interface is not known at the moment of writing the rule (when server gets external ip dynamically).

How to Set up Port Forwarding with iptables | Ivo Berger

iptables - Does NAT-ing rewrite the source IP in packets iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 2222 -j DNAT --to 10.3.3.3:22 but when I try to connect, I get no response. Running tcpdump on the bastion shows that traffic is getting through, so I assume I'm hitting the app server's VPC security groups and not getting as far as port 22 on it. NAT with iptables : super fast tutorial $ iptables -t nat -A POSTROUTING -s @priv -o eth1 -j SNAT --to-source @pub. If the packet is coming from @priv, let's put it on our output interface eth1 and jump to the Source Nat Protocol that will modify the packet so it has the public address (@pub) as source. Here! You did it. One private IP address mapped to one public IP address. Dynamic Iptables Postrouting with SNAT for a paritcular I want to define a rule in iptables for postrouting in ubuntu as below: $IPTABLES -t nat -A POSTROUTING -o $EXTIF -p tcp -d xxx.xx.xx.8 -j SNAT --to-source xxx.xx.xx.238 How To List and Delete Iptables Firewall Rules | DigitalOcean