Cloudflare 推出了 Spectrum，文章標題提到的 65533 應該是指 80 & 443 以外其他的 port：「Introducing Spectrum: Extending Cloudflare To 65,533 More Ports」。
然後因為 TCP proxy 不像 HTTP proxy 與 WebSocket proxy 可以靠 Host header 資訊判斷，在 TCP proxy 需要獨占 IP address 使用 (i.e. 一個 IP address 只能給一個客戶用)，而因為 IPv4 address 不夠的關係，這個功能只開放給 Enterprise 客戶用：
Today we are introducing Spectrum, which brings Cloudflare’s security and acceleration to the whole spectrum of TCP ports and protocols for our Enterprise customers.
雖然現在限定在 Enterprise 客戶，但 Cloudflare 還是希望看看有沒有其他想法，目前提出來的選項包括了開放 IPv6 address 給所有人用，或是變成獨立付費項目：
Why just Enterprise? While HTTP can use the Host header to identify services, TCP relies on each service having a unique IP address in order to identify it. Since IPv4 addresses are endangered, it’s quite expensive for us to delegate an IP per application and we needed to limit use. We’re actively thinking about ways to bring Spectrum to everyone. One idea is to offer IPv6-only Spectrum to non-Enterprise customers. Another idea is let anyone use Spectrum but pay for the IPv4 address. We’re not sure yet, but if you prefer one to the other, feel free to comment and let us know.
類似的產品應該是 clean pipe 類的服務，但一般 clean pipe 是透過 routing 重導清洗流量，而非像 Cloudflare 這樣設計... 不知道後續會有什麼樣的變化。
