A "Free" Relay Attack Taking Advantage of The Lack of Full-RBF In Core

The discussion within the Bitcoin development community highlights the complexities and nuances of transaction relay policies across different nodes. A significant point of contention is the alignment of Bitcoin Core's default settings with the actual practices of miners, particularly concerning the mempoolfullrbf setting. The conversation reveals that a considerable portion of the mining hashrate has adopted mempoolfullrbf, suggesting a need for Bitcoin Core to adjust its settings to mirror this widespread practice. This adjustment is crucial for maintaining consistency and predictability in transaction relays, ensuring that users' transactions are treated uniformly across the network.

Moreover, the debate underscores the existence of divergent mempool policies among nodes, which leads to a situation where only certain transactions are relayed by specific subsets of nodes. This fragmentation within the network raises concerns about the efficiency and reliability of transaction processing and propagation. The acknowledgment of these diverging policies by key figures in the community, such as Peter Todd, emphasizes the importance of finding a consensus on default settings that accommodate the majority of the network's practices. Such a consensus is essential for the smooth operation of the Bitcoin network, ensuring that transactions can be reliably and predictably processed across the entire node landscape.