Abstract: A method including receiving, by a blockchain node from a peer blockchain node, a total amount of messages indicating blockchain transactions, the total amount of messages including at least one announcement message that contains an identifier to identify a blockchain transaction and at least one entire-transaction message that describes the blockchain transaction; determining, by the blockchain node based on receiving the total amount of messages, a first amount of announcement messages and a second amount of entire-transaction messages; calculating, by the blockchain node, a ratio of the second amount of messages to the total amount of messages; comparing, by the blockchain node, the calculated ratio to a predetermined threshold ratio; and determining, by the blockchain node based on a result of the comparison, whether a peer blockchain client utilized by the peer blockchain node has been modified is disclosed. Various other aspects are contemplated.