Skip to content

Deploying a Validator Node#


As explained in the Validator Nodes page, these servers fulfill a critical role in securing the network:

  • They check that all received transactions are valid.
  • They run a consensus algorithm so that all validators in the network agree on the transactions to add to the blockchain.
  • Finally, they add the agreed-upon transactions to their copy of the ledger.

Additionally, all blockchains must employ measures against Sybil attacks and the Flare network is planning two such measures:

  • Validators will need to stake native tokens, just like in regular Proof of Stake.
  • Validators will also need to be FTSO Data Providers, and their performance in this role will have an impact on their validation rewards, leading to a meritocratic system.

However, given the importance of the validator role and the novelty of the meritocratic approach, these measures are being implemented in phases:

Implementation phases

  • Phase 0:

    Only validators with preregistered keys can be deployed.

    Some users will receive preregistered validator keys, this is, the keys required to launch a node which has already been registered as a validator. This is the only way to deploy a validator node during this phase.

  • Phase 1:

    Candidate FTSO validators.

    FTSO data providers that wish to become validators need to undergo a KYC process (Contact Tom T. over Discord (Tom T#7603), Telegram (@TampaBay7) or email) and operate an Observer node.

    Random security scans will be performed on the node, and if all of them are successful (see Mandatory security measures below) validator rewards will be accrued. Validator rewards are split evenly among all candidate validators that passed the security scans.

More phases will be added as the process is refined.

Information affecting only specific phases is indicated in this guide with colored boxes like this one.

This guide explains how to deploy your own validator node so you can participate in the consensus and collect the rewards that the network provides to those who help secure it.

The following instructions apply to the Flare network only.


Validators run the same software as regular observer nodes, therefore, this guide assumes you have already read the Deploying an Observer Node guide.

The requirements to deploy a validator node are the same as for observer nodes, except on the CPU and RAM front which are heavier due to the extra work required:

Hardware Software
CPU cores 16 Operating System Ubuntu (18.04 or 20.04) or macOS (>= 10.15 Catalina)
RAM 64 GB Dependencies Go (>= 1.18.5)
Disk space 1 TB SSD gcc
Disk growth 2.5 TB/year g++
npm (>= 8.11)


1. Configure the Node#

A validator node is deployed like an observer node, but there are some additional considerations.

Firstly, validators do more work than plain observer nodes so please consider the recommended hardware specifications above.

And secondly, validator security impacts the whole network. Please consider the following items carefully:

Mandatory security measures#

  • Ensure port 9650 is not externally reachable. This is the port used to answer API requests and validators should not be doing that.

  • Disallow password authentication over SSH.

  • Don't run any non-validator services on the same IP (website, mail server, etc).


A monitoring tool run by Flare periodically checks that the above measures are followed by all validators.

Failure to comply impacts the validator's rewards.

Phase 1 exemption

To ease the deployment of candidate validators during phase 1 port 9650, used to answer API requests, might be left open.

This allows running the candidate validator on the same machine currently running the observer node used to submit FTSO data.

Suggested security measures#

  • Disallow any ICMP traffic.

  • Have the machine firewalled. Only the ports required for validator operation should be open (i.e. only the staking port, which defaults to 9651).

    If you use a virtual server, use only its web interface for management and close the SSH port.

    If the SSH port must be open, it should ideally be restricted to a private IP (i.e. only accessible through VPN) or only temporarily open to the operator's office/home static IP or a bastion SSH VM that can be turned off between use.

  • The node should only act as a validator, and not accept RPC API calls.

    You should deploy a separate observer node for tasks requiring RPC API access. Additionally, this observer node can point to your validator for peering and bootstrapping.

  • The validator should only enable the minimum set of EVM APIs by adding this line to a configuration file:

    "eth-apis": [
    Sample configuration file for validator nodes
    "snowman-api-enabled": false,
    "coreth-admin-api-enabled": false,
    "coreth-admin-api-dir": "",
    "eth-apis": [
    "continuous-profiler-dir": "",
    "continuous-profiler-frequency": 900000000000,
    "continuous-profiler-max-files": 5,
    "rpc-gas-cap": 50000000,
    "rpc-tx-fee-cap": 100,
    "preimages-enabled": false,
    "pruning-enabled": false,
    "snapshot-async": true,
    "snapshot-verification-enabled": false,
    "metrics-enabled": true,
    "metrics-expensive-enabled": false,
    "local-txs-enabled": false,
    "api-max-duration": 30000000000,
    "ws-cpu-refill-rate": 0,
    "ws-cpu-max-stored": 0,
    "api-max-blocks-per-request": 30,
    "allow-unfinalized-queries": false,
    "allow-unprotected-txs": false,
    "keystore-directory": "",
    "keystore-external-signer": "",
    "keystore-insecure-unlock-allowed": false,
    "remote-tx-gossip-only-enabled": false,
    "tx-regossip-frequency": 60000000000,
    "tx-regossip-max-size": 15,
    "log-level": "info",
    "offline-pruning-enabled": false,
    "offline-pruning-bloom-filter-size": 512,
    "offline-pruning-data-directory": ""

2. Run the Node#

After taking the above considerations into account, you can now start up your node by following the Deploying an Observation Node guide.

Preregistered validator keys

Some users have received preregistered validator keys, this is, the keys required to deploy a node which has already been registered as a validator.

If that is your case, you just need to add these parameters to the launch command line, and jump to step 6.

--staking-tls-cert-file=<NODE_CRT_PATH> \

Last update: 2023-06-06