Beyond the Nat: Cgnat, Bandwidth, and Practical Tunneling

Summary

Home internet in the 90s felt simple. You plugged into Ethernet, got an IPv4 address, and you could expose a service directly. Today the path is layered and driven by economics. IPv4 did not end in a hard way. It became scarce and costly, see IPv4 address exhaustion. Data centers and enterprises still buy and route IPv4. Most residential users are placed behind Carrier-grade NAT (CGNAT) and many providers mix in IPv6 to keep compatibility while lowering costs. This post maps that landscape with a practical lens. We will move from end to end addressing to provider networks that multiplex thousands of customers behind a few public IPs using NAT. CGNAT saves addresses and reduces ISP costs, but it blocks inbound connectivity, see NAT traversal. It also complicates games, VoIP, and P2P, and makes self-hosting fragile without extra tools. Bandwidth is often sold as “speed,” yet what matters in practice is capacity, symmetry, and guarantees. Residential links are usually asymmetric and best effort. Business uplinks and servers provide symmetric throughput, static addressing, and a Service Level Agreement. Not every outage comes from a bad actor. Popularity surges can mimic attacks, see the Slashdot effect. Misconfigured bots can overwhelm a small uplink much like a targeted DDoS. If CGNAT blocks your ports you still have options. Tunneling restores reachability by creating an outbound path to a reachable endpoint, see tunneling protocol. We will set up a simple reverse tunnel with bore-cli. We will also use Cloudflare Tunnel, which gives you an outbound only connection that terminates at the Cloudflare edge with HTTPS. But, remember, always follow your ISP’s terms of service when exposing services through tunnels. What you will learn The path from end to end IPv4 to CGNAT and mixed IPv6 deployments, with links for deeper reading Why capacity, symmetry, and SLA matter more than headline Mbps How DDoS and self DDoS relate to capacity, not only to malice Step by step tunneli...