Network-level censorship: Understanding the problem

Running applications inside a Trusted Execution Environment (TEE) such as Intel TDX does not prevent a host from censoring network traffic, since all traffic passes through the host's network stack. This matters for blockchain systems such as Flashbots' BuilderNet, where the host could block or delay transactions before they reach the block builder. Encryption hides payload contents but not IP addresses, ports or traffic patterns, and packets can be silently dropped or delayed, such as by 850ms, so a transaction misses the current block.