Integration Guide for Validator

Decision Make

When activating MEV functionality, validators encounter a mix of opportunities and challenges. Before enabling this feature, validators need to carefully evaluate these risk accordingly:

1. More maintenance work. Apart from the validator, additional maintenance of the Sentry service and its related network components is required.

2. Network risk. Due to Sentry service being exposed to the public network, it is inevitably susceptible to possible network attacks.

3. Financial risk. Validators need to pay fees to builders, securely managing accounts is a crucial topic.

After identifying these risks, let’s begin the journey.

Validator Topology

It is suggested that to split the internal network into two part:

1. Private network. The private network is isolated from the public network. All access to components within this network is strictly restricted. The Validator and Payment wallet are expected to be deployed within a private network environment.

2. Nat network. The components in this network can communicate with the public internet under certain constraints, and the communication can be established through load balancers provided by various cloud platforms. Sentry service should be deployed within a NAT network environment. It is essential to configure appropriate safeguards on the network gateway to prevent DoS attacks and other potential threats.

The validator should open its RPC access to the mev-sentry. The mev-sentry should open its RPC to the public network with a domain host. The information of validator should be registered in bsc-mev-info.

Hardware Spec

Mev-Sentry: The recommended specifications for the mev-sentry machine are 2 CPUs and 4 GB of RAM.

Preparation

The BNB Chain community has maintained an open-source version of the Sentry service. You can clone the code repository from here.

Before actually deploying the Sentry service, it is crucial to carefully consider and determine several key parameters:

1. BidFeeCeil. This represents the maximum fee that a validator is willing to pay for a block proposed by a builder. When this value is 0, it signifies that the validator does not accept any charges from the builder.

2. BidSimulationLeftOver. This parameter indicates how long before the block time the validator should cease simulating the blocks from the builder. It is generally advisable to set it to a few tens of milliseconds. Setting it too small may result in blocks being broadcast too late and subsequently discarded during network congestion.

It is suggested to purchase a domain that is related to the moniker name of the validator. The builders will send requests through this domain. A BSC account should be created in advance as the payment account. No BNB is required in that account if BidFeeCeil is zero, otherwise, it needs to be ensured that there is enough balance in the account.

Go to the bsc-mev-info repo to find more information about running builders which will be used during setup.

Quick Setup

Step 1: Setup Sentry.

Deploy the sentry service according to the readme of sentry repo.

Here are a few key points to highlight.

• ❗❗❗This is an important security notice: Please do not configure any validator’s private key in the config file of the sentry. Please create entirely new accounts as pay bid accounts.

• One sentry service can manage multiple validators.

• The PrivateURL of validator is used by the sentry to access the validator, it can be IP:Port or internal domain URL.

• The PublicHostName of validator is used by the builder to access the validator, the sentry will forward to different validators according to different hostname of the request.

• For each Builder, define its Address and public URL. The address will be used to authorize the identity of builders.

Step 2: Change the Config of Validator.

Upgrade the validators to version v1.4.x or later, add a few new sections in the config.toml. Example:

  [Eth.Miner.Mev]
  Enabled = true # open bid receiving
  ValidatorCommission = 100 # validator claim 1% from block reward
  BidSimulationLeftOver = 50000000 # 50ms, the time left for bid simulation
  SentryURL = "http://bsc-mev-sentry.io" # it is used for the validator to access the sentry, it should be a private URL or IP:Port.

  # Find builders in [bsc-mev-info](https://github.com/bnb-chain/bsc-mev-info)

  [[Eth.Miner.Mev.Builders]]
  Address = "0x45EbEBe8...664D59c12" # builder address which validator is willing to receive bid from

  [[Eth.Miner.Mev.Builders]]
  Address = "0x980A75eC...fc9b863D5" # builder address which validator is willing to receive bid from

Step 3: Publish information

It is highly recommended to publish information in bsc-mev-info so other builders can find it.