Keeper

A keeper is a bot that does a protocol's routine work. Contracts can't wake themselves up, so someone has to send the transaction that harvests rewards, rebalances a position, updates a price or liquidates a loan. That someone is a keeper.

Keepers are usually ordinary accounts or bots. Some are run by the protocol team, some by outside operators who are paid a fee for each call.

Why keepers are a security question

The functions a keeper calls often move funds. That leaves two designs, and each needs its own checks:

• Restricted. Only listed keeper addresses may call the function. Then the contract must actually check the caller, on every path, including any helper or multicall contract that forwards calls on the keeper's behalf.
• Public. Anyone may call it, because the protocol wants it to run even if its own bot is down. Then every argument the caller controls is attacker input: which pool to swap through, how much to accept, where to send the result. A public harvest that lets the caller pick the pool, with no minimum amount out, can be pointed at a pool the attacker built.

What to check

List every function a keeper is meant to call. For each one, decide whether it is restricted or public, and test it from a random address. A restricted function must revert. A public one must give the same result whoever calls it.