specification/protocol/network/messages/verack.md

Handshake: Acknowledge ("verack")

The verack message is sent in reply to a version message. Sending a verack in response to a version message indicates to the remote that its connection and version has been accepted.

There is no version negotiation functionality between nodes; therefore if the node does not accept the version supplied by the remote then the node disconnects instead of responding with a verack.

This verack message consists of only a message header; the command string is "verack".