The initial public IP address of the range that will be used for CGNAT. This is the IP that will be shared among multiple internal clients. Example: 200.189.189.0
Defines the size of the available public IP range. A smaller mask (e.g., /25) allows more public IPs, while a larger one (e.g., /30) allows fewer IPs. Example: 255.255.255.128 (/25)
The first IP address of the internal range that will be assigned to clients. This is the private range that will be translated to public IPs. Example: 100.64.0.0
Number of TCP/UDP ports that each internal client can use simultaneously. More ports allow more simultaneous connections but reduce the number of clients that can share the same public IP. Example: 2000 ports
Defines how many internal IPs should be "skipped" before starting assignment. Useful for continuing an existing configuration or reserving IPs for other purposes. Default value: 0
CGNAT (Carrier-Grade NAT) is a network address translation technique used by Internet Service Providers (ISPs) to share a single public IP address among multiple customers. With the scarcity of IPv4 addresses, CGNAT allows operators to serve more users without acquiring new public IP blocks.
Fill in the fields with the public network address, subnet mask, initial internal IP, and number of ports per client. The generator automatically calculates the NAT rules and produces a script ready to be imported into your Mikrotik router via terminal or Winbox.
The generated script is compatible with RouterOS and can be applied directly on Mikrotik. The rules are generated in RouterOS firewall/NAT format, ensuring high performance and granular port control per client in CGNAT environments.
This generator is provided free of charge by Made4it for the ISP and network technician community. No account creation or software installation is required — just fill in the form and copy the generated script.