Yes, in MikroTik RouterOS you can configure both IPv4 with NAT for private addresses (invalid on the Internet) and implement IPv6 with valid global addresses simultaneously.

This configuration allows devices within a local network to communicate with each other and with the Internet using IPv4, while taking advantage of IPv6 for external communication, where each device can have a unique IPv6 address.

For keep invalid IPv4 with NAT, NAT (Network Address Translation) is generally configured so that private IP addresses on the local network (such as those in the ranges 192.168.xx, 10.xxx, 172.16.xx – 172.31.xx) are translated to a public IP address valid for Internet access.

This is commonly done with masquerade rules in the firewall section of MikroTik RouterOS, allowing multiple devices on a LAN to access the Internet through a single public IP address.

For deploy IPv6 with valid addresses, you need to configure your network and devices for IPv6. This includes obtaining a block of IPv6 addresses from your Internet Service Provider (ISP), configuring IPv6 routing on your MikroTik device, and assigning IPv6 addresses to devices on your network.

RouterOS supports IPv6 and can be configured to assign IPv6 addresses through DHCPv6 or SLAAC (Stateless Address Autoconfiguration), allowing each device to have a unique global address on the Internet.

Basic Steps for Configuration

1. Configure NAT for IPv4:
   • Go to IP > Firewall > NAT and add a masquerade rule for your Internet exit interface. This translates your private IP addresses to a public IP address for outbound traffic.
2. Enable and Configure IPv6:
   • Make sure IPv6 packaging is enabled in System > Packages.
   • Configure IPv6 routing by obtaining an IPv6 prefix from your ISP and assigning it to your network. You can use DHCPv6 client to obtain a prefix and then advertise it on your network using NDP (Neighbor Discovery Protocol).
3. Assign IPv6 Addresses to Devices:
   • You can configure a DHCPv6 server or use SLAAC on your local network to assign IPv6 addresses to devices on your network.

Deploying both IPv4 with NAT and IPv6 in a network environment allows administrators to take advantage of the wide availability of IPv6 addresses while maintaining compatibility with devices and services that still rely on IPv4.

This dual-stack configuration is common practice during the transition from IPv4 to IPv6, ensuring that network resources are accessible from both IPv4 and IPv6 networks.