Setup NAT on Proxmox like an expert with the help of this handy guide from Bobcares. 

At Bobcares, we offer solutions for every query, big and small, as a part of our Server Management Service.

Let’s take a look at how our Support Team recently helped out a customer setup NAT on Proxmox.

How to setup NAT on Proxmox

Proxmox utilizes bridge networking in order to offer internet access to virtual machines. Furthermore, we need a public IP for each machine. In case we have access to only a certain amount of IPs, we can utilize NAT in order to access the Internet on the machines.

However, our Support Techs recommend having a static public IP while running public services. So let’s take a look at how to set up NAT on Proxmox to offer private networks to virtual machines.

This process involves the following steps:

1. Create a bridge
2. Bring up the NAT bridge
3. Configure Virtual Machine
4. Port forwarding to access from the outside world

Setup NAT on Proxmox: Create a bridge

Our Support Techs recommend the following process to successful configure a NAT bridge:

1. First, we will log in to the proxmox host ssh and run the following command:

   nano /etc/network/interfaces

   This command opens up the network configuration file.
2. Next, paste the following at the end of the configuration file:

   auto vmbr2
   #private sub network
   iface vmbr2 inet static
           address  192.168.1.1
           netmask  255.255.255.0
           bridge_ports none
           bridge_stp off
           bridge_fd 0
    
           post-up echo 1 > /proc/sys/net/ipv4/ip_forward
           post-up   iptables -t nat -A POSTROUTING -s '192.168.1.0/24' -o vmbr1 -j MASQUERADE
           post-down iptables -t nat -D POSTROUTING -s '192.168.1.0/24' -o vmbr1 -j MASQUERADE

   Here, vmbr1 is the bridge name for NAT while vmbr2 is the interface configured on the network file. We are setting bridge_ports
   to none as we are not connecting to the outside world directly.

Setup NAT on Proxmox: Bring up the NAT bridge

The next step involves using the command below to bring up the bridge we configured in the previous section:

ifup vmbr2

Setup NAT on Proxmox: Configure Virtual Machine

This step involves configuring the virtual machine using the IP address. We have to manually set up the IP address as DHCP is not present. We can use the following details depending on the OS:

• IP: 192.168.1.2
• Netmask: 255.255.255.0
• Gateway: 192.168.1.1

We can use the following IPs for further virtual machines:

• 192.168.1.3
• 192.168.1.4
• ..upto 254

We can also use Google DNS for DNS:

• 8.8.8.8
• 8.8.4.4

Setup NAT on Proxmox: Port forwarding to access from the outside world

If we are working with a Linux guest, we can access ssh through the public IP of the main server. In this scenario, we will run the following command on proxmox host.

iptables -t nat -A PREROUTING -i vmbr1 -p tcp --dport 3033 -j DNAT --to 192.168.1.2:22

In this example, we are forwarding host port 3033 to guest port 22. After that we will run the command below in order to access guest SSH:

ssh -p 3033 root@ip.of.proxmox.host

This command will prompt for the password. Once we enter the password, we can successfully connect to guest SSH.

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Conclusion

At the end of the day, our skilled Support Engineers at Bobcares configuring NAT on Proxmox.