Skip to main content

How add NAT in Linux?

How add NAT in Linux?


  1. Configure first NIC card, eth0 for Internet with a Public (IP External network or Internet).
  2. Configure second NIC crad, eth1 for LAN with a Private IP (Internal private network).
  3. Configure Gateway.
  4. Configure /etc/resolv.
  5. Delete all the iptables rules present, specially NAT.
  6. Set up IP FORWARDing and Masquerading.

How do I get NAT on Ubuntu?

Now, follow the steps below:

  1. First check the IP addresses on both the machines with the command:
  2. Also check the connectivity of the machines before configuring the NAT router as mentioned above.
  3. On VM2 open the sysctl.conf file and set the “net.ipv4.ip_forward” parameter to one by uncommenting it:

How do you check if nat is enabled Linux?

Linux Iptables List and Show All NAT IPTables Rules Command

  1. Syntax. The syntax is as follows for iptables command as root user to display IPv4 rules:
  2. Say hello netstat-nat. The netstat-nat command display the natted connections on a Linux iptable firewall:
  3. Summing up.

How do I find my nat IP address Linux?

Type the following dig (domain information groper) command on a Linux, OS X, or Unix-like operating systems to see your own public IP address assigned by the ISP: $ dig +short You can also type: $ dig TXT +short

What is NAT in Ubuntu?

NAT or Network Address Translation allows multiple computers on a private network to share a common IP to access the Internet. One set of IP addresses is used inside the organization and the other set is used by it to present itself to the internet. This helps in conserving limited public IP space.

What is the source NAT?

Source NAT is the translation of the source IP address of a packet leaving the Juniper Networks device. Source NAT is used to allow hosts with private IP addresses to access a public network.

Does NAT change the source port?

Network address translation (NAT) changes the source or destination IP address or port for packets traversing the firewall. In static source translation (one-to-one source translation), the source IP address of a certain host is always translated using the same specific IP address.

How do I create a NAT router in Linux?

The Linux kernel usually posesses a packet filter framework called netfilter (Project home: This framework enables a Linux machine with an appropriate number of network cards (interfaces) to become a router capable of NAT. We will use the command utility ‘iptables’ to create complex rules for modification and filtering of packets.

How do I use NAT in iptables?

All our commands regarding NAT will start like this: # # iptables -t nat […] This selects the nat -table. There are two other tables, namely mangle und filter, but those are not used for NAT and therefore I mention them for completeness only. Since the default table is filter we have to select the nat table every time again.

How to add NAT rules to the POSTROUTING chain?

This command can be explained in the following way: select table “nat” for configuration of NAT rules. Append a rule to the POSTROUTING chain (-A stands for “append”). the action that should take place is to ‘masquerade’ packets, i.e. replacing the sender’s address by the router’s address.

Can I use Ubuntu VM as a NAT router?

For this we will use an Ubuntu VM as NAT router and another Ubuntu VM as client VM for the purpose of testing. To test the setup, we are using Virtualbox for creating and managing virtual machines (VMs). Two Ubuntu VMs with one having two network interfaces (NICs).