Knowledge Base

How does the C-Servers ExtraNAT service work?

So far, all C-Servers offers had been split in three families:
- a family of NAT IPv4 servers and products, called MultiNAT, with a single IPv4 NAT guaranteed, IPv6 possible (not guaranteed, upstream-dependant) and a free-range of 150 opened ports;
- a family of hybrid IPv6 and transitional 6-to-4 servers and products, called MultiVPS, which is our core offer, comprising a single IPv6 guaranteed and a dynamic IPv4 address serving HTTP/HTTPS access to the Internet where IPv6 is not supported;
- a family of previously-used servers and products, called VPS Outlet, similar to MultiVPS, more performance-limited, but with competitive pricing, perfect for undemanding users.

Effective from September 29th, and especially after some uptime and other technical difficulties in August with the port forwarding services at the Zeta2 Finland server, C-Servers will transfer all MultiNAT customers to the MultiVPS service, and in turn, the MultiVPS service will have an entire new network access available: the C-Servers ExtraNAT, included in the MultiVPS core service for all current customers at Zeta3 Finland (65.108.71.165) and Zeta1 Germany (116.202.80.221), and free of any extra charge for existing customers.

This is being improved and optimized on the next 1-2 days, meaning that it's recommended for you to wait up until October 2nd to start NAT deployments, as we are finalizing some procedures. As of September 30th, 2024, 19h05, this is the current status of this new implementation:

DNS64, NAT64, NAT46: All fully implemented and working on the Zeta3 Finland and the Zeta1 Germany.

What are the advantages of the ExtraNAT service?

Actually, several of them. It's a service that makes IPv4 easier, faster, and seamless:

• All DNS queries have started to be done on the same server. This is possible through Bind9. Lower latency, therefore, to use the service.
• All TCP/UDP queries, above port 10000, are now done via Tayga and Nginx. Tayga acts as a regular NAT64; Nginx acts as a reverse proxy, or NAT46. Outbound ports are unlimited in scope and request and directly mapped one-to-one with the external, fixed IP, since they are processed at the Network layer 3; inbound ports, executed by Nginx and recieved from the fixed IP, are simple and easy to calculate, pre-allowed up to 10 without any intervention necessary on your end, and allocated on a per-IPv6-address basis. Traffic bandwidth is exactly the same one that you already had on your VPS, since it's the very same server, no extra latency or traffic consumption are added.
• In the event some component is not working as it should (DNS64 or NAT64), the regular fallback via the NAT64 public service is still implemented. It's hard to occur, but it may happen. However, Nginx will always stay unaffected, ensuring inbound port forwarding principles to the VPS are executed as expected for a reverse proxy. Previously, we employed HAProxy - we've chosen a different, resilient solution, this time.
• The external IPv4 for this NAT service is exactly the same as the dedicated server's IPv4. No more, no less. 

Therefore, this is a NAT in full right, and the first dual-stack offer C-Servers brings, actually a technical first on the SolusVM 2 platform, contouring around the lack of NAT IPv4 on the platform, and also a technical first for NAT46 on any hosting provider, worldwide. This is the result of a complex configuration process, including automatic scripting of Nginx, optimization of bind9 and Tayga, and their respective implementations.

How is HTTP/HTTPS handled on this configuration?

This is the only area that remains as before on the MultiVPS, although with some changes: if you wish to use ports 80/443 for web hosting or other HTTP/HTTPS traffic, this is still handled from your VPS with both IPv6 and the NAT64/DNS64, the sole difference being you'll have a fixed IPv4 now (on the main resolver).

You shall use any dual-stack CDN, for example Cloudflare Tunnels or BunnyCDN, in order to have a hosting panel included, and should also be ready to have a backup solution if and when the fixed IPv4 of the main resolver is down and prevents you from accessing your panel - usually accessing via VNC at localhost:your-panel-port through a GUI fixes this difficulty. Needless to say, having an IPv6-preferred panel is preferential, but not mandatory. 

I heard right? TCP and UDP supported?

Exactly. Tayga and Nginx are configured to support both. When you know the sender/reciever IPs, it's easy to allow it. This is a direct advantage compared to other providers.

How can I configure ports?

Answered now in a separate article: https://web.c-servers.co.uk/info/how-do-i-calculate-the-port-range-for-ipv4-nat 

What will happen to the Zeta2 Finland server?

Due to our lack of management tools at the upstream, which have caused extra downtime, and the fragility of the solution with Virtualizor under some very particular questions (of which HAProxy and iptables are the biggest examples), the server will be discontinued, starting from October 1st, 2024.