Relayers are nodes that get data from the source chain and submit them to the target chain. These nodes are crucial for TeleportDAO since they provide the input for the Relay contract. In most cases, the data that Relayers provide is the block header of the source blockchain.
To become Relayer, a node runs the Relayer script. This script connects the Relayer to a few full nodes of the source chain to get the latest block headers. Relayer script is lightweight so it can be run on a personal computer.
Submitting and verifying block headers on the blockchain has some costs for Relayers. To compensate for this cost, Relay takes fees from users and pays them to the Relayers. The fee covers the gas amount used for submitting and verifying the block header, plus an extra reward for the Relayer.
The Relay contract checks the correctness of the submitted data and sends a reward to the Relayer who provided the valid data faster. If a Relayer provides a false or staled block header, this header gets rejected by the Relay contract and the Relayer loses the paid gas fee. Therefore, a malicious Relayer cannot cause any harm to the system.
TeleportDAO's Relayers network is a decentralized network. Anyone can become a Relayer in TeleportDAO and compete to collect rewards. Having a good bandwidth can help a Relayer to get more rewards. It is important to note that in every case, on top of a secure blockchain, TeleportDAO is safe, and as long as one honest Relayer exists in the system, TeleportDAO has liveness.