Polkadot Secure Validator Setup

This repo describes a potential setup for a polkadot validator that aims to prevent some types of potential attacks.

How to use

This repo has code for creating a complete implementaion of the approach described here from scratch, included both layers described in Workflow. This can be done on a host with node, yarn and git installed with:

$ git clone https://github.com/w3f/secure-validator
$ cd secure-validator
$ yarn
$ cp config/main.sample.json config/main.json
$ yarn sync

You will need credentials as environment variables for all the infrastructure providers used in the platform creation phase (AWS, Azure, GCP and packet).

You can also just provision a set of previously created machines with the ansible code here. We have provided an example inventory that you can customize.

Structure

The secure validator setup is composed of a bare-metal machine that runs the actual validator and a set of cloud nodes connected to it. The validator is isolated from the internet and only has access to the polkadot network through the cloud nodes, which are accessible from the internet and are connected to the rest of the polkadot network.

The connection between the validator node and the cloud nodes is performed defining a VPN to which all these nodes belong. The polkadot instance running in the validator node is configured to only listen on the VPN-attached interface, and uses the cloud node's VPN address in the --reserved-nodes parameter. It is also protected by a firewall that only allows connections on the VPN port.

This way, the only nodes allowed to connect to the validator are the public nodes through the VPN. Messages sent by other validators can still reach it through gossiping, and these validators can know the IP address of the secure validator because of this, but can't directly connect to it without being part of the VPN.

WARNING

If you use this tool to create and/or configure your validator setup or implement your setup based on this approach take into account that if you add public telemetry endpoints to your nodes (either the validator or the public nodes) then the IP address of the validator will be publicly available too, given that the contents of the network state RPC call are sent to telemetry.

Even though the secure validator in this setup only has the VPN port open and Wireguard has a reasonable approach to mitigate DoS attacks, we recommend to not send this information to endpoints publicly accessible.

Workflow

The secure validator setup is structured in two layers, an underlaying platform and the applications that run on top of it.

Platform creation

Because of the different nature of the validator and the cloud nodes, the platform is hybrid, consisting of a bare-metal machine and cloud instances. However, we use terraform for creating both. The code for setting up the bare- metal machine is in this repothey up is in terraform-modules dir.

The cloud instances are created on 3 different cloud providers for increased resiliency, and the bare-metal machine on packet.com. As part of the creation process of the cloud instances we define a hardware firewall to only allow access on the VPN and p2p ports.

Application creation

This is done through the ansible playbook and roles located at ansible, the configuration applied depend on the type of node:

Common:
- Software firewall setup, for the validator we only allow the VPN and SSH ports, for the public nodes VPN SSH and p2p ports.
- VPN setup: for the VPN solution we are using WireGuard, at this stage we create the private and public keys on each node, making the public keys available to ansible.
- VPN install: we install and configure WireGuard on each host using the public keys from the previous stage. The configuration for the validator looks like:
```
[Interface]
PrivateKey = <...>
ListenPort = 51820
SaveConfig = true
Address = 10.0.0.1/24

[Peer]
PublicKey = 8R7PTv1CdNLHRsDvrvE58Ac0Inc9vOLY2vFMWIFV/W4=
AllowedIPs = 10.0.0.2/32
Endpoint = 64.93.77.93:51820

[Peer]
PublicKey = ZZW6Wuk+YjJToeLHIUrp0HAqfNozgQfUMo2owC2Imzg=
AllowedIPs = 10.0.0.3/32
Endpoint = 50.81.184.50:51820

[Peer]
PublicKey = LZHKtuGCxz9iCoNNDmQzzNe9eF9aLXj/4yJRkFjCWzM=
AllowedIPs = 10.0.0.4/32
Endpoint = 45.243.244.130:51820
```
- Polkadot setup: create a polkadot user and group and download the binary.
Public nodes:
- Start Polkadot service: the public nodes are started and we make the libp2p peer id of the node available to ansible. The generated systemd unit looks like:
```
[Unit]
Description=Polkadot Node

[Service]
ExecStart=/usr/local/bin/polkadot --name sv-public-0

Restart=always

[Install]
WantedBy=multi-user.target
```

Private (validator) node:

Start Polkadot service: the private (validator) node is started with the node's VPN address as part of the listen multiaddr and the multiaddr of the public nodes (with the peer id from the previous stage and the VPN addresses) as reserved-nodes. It looks like:

[Unit]
Description=Polkadot Node

[Service]
ExecStart=/usr/local/bin/polkadot \
    --name sv-private \
    --validator \
    --listen-addr=/ip4/10.0.0.1/tcp/30333 \
    --reserved-nodes /ip4/10.0.0.2/tcp/30333/p2p/QmNpQbu2nKfHQMySnCue3XC9mAjBfzi8DQ9KvNwUM8jZdx \
    --reserved-nodes /ip4/10.0.0.3/tcp/30333/p2p/QmY81TLZKeNj4mGDAhFQE6RrHEJPidAkccgUTsJo7ifNFJ \
    --reserved-nodes /ip4/10.0.0.4/tcp/30333/p2p/QmTwMDJDnPyHUHV2fZFcVbNpYzp6Fu7LP6VhhK3Ei13iXr

Restart=always

[Install]
WantedBy=multi-user.target

Scopes

This setup partitions the network in 3 separate kind of nodes: secure validator, its public node and the regular network nodes, haveing each group a different vision and accessiblity to the rest of the network. To verify this, we'll execute the system_networkState RPC call on nodes of each partition:

curl -H "Content-Type: application/json" --data '{ "jsonrpc":"2.0", "method":"system_networkState", "params":[],"id":1 }' localhost:9933

Validator

It can only reach and be reached by its public nodes, from the system_networkState RPC call:

{

  [ ........ ]

  "result": {
    "connectedPeers": {

      [ only validator's public nodes shown here]

      "QmPjNcWNZjNrjVFzkNYR6jH7HLqyU7j9piczUyNoxce1fD": {
        "enabled": true,
        "endpoint": {
          "dialing": "/ip4/10.0.0.2/tcp/30333"
        },
        "knownAddresses": [
          "/ip6/::1/tcp/30333",
          "/ip4/10.0.0.2/tcp/30333",
          "/ip4/127.0.0.1/tcp/30333",
          "/ip4/172.26.59.86/tcp/30333",
          "/ip4/18.197.157.119/tcp/30333"
        ],
        "latestPingTime": {
          "nanos": 256512049,
          "secs": 0
        },
        "open": true,
      },

      [ ........ ]

    },
    "notConnectedPeers": {

      [ always known regular nodes: boot nodes, other validators, etc ]

      "QmP3zYRhAxxw4fDf6Vq5agM8AZt1m2nKpPAEDmyEHPK5go": {
        "knownAddresses": [
          "/dns4/p2p.testnet-4.kusama.network/tcp/30100"
        ],
        "latestPingTime": null,
        "versionString": null
      },

      [ ........ ]

    },
    "peerset": {

      [ all known nodes shown here, only reported connected to validator's public nodes ]

      "QmPjNcWNZjNrjVFzkNYR6jH7HLqyU7j9piczUyNoxce1fD": {
        "connected": true,
        "reputation": 1114
      },
      "QmP3zYRhAxxw4fDf6Vq5agM8AZt1m2nKpPAEDmyEHPK5go": {
        "connected": false,
        "reputation": 0
      },

      [ ........ ]

      "reserved_only": true
    }
  }
}

Validator's public nodes

They can reach and be reached both by the validator and by the network regular nodes:

{

  [ ........ ]

  "result": {
    "connectedPeers": {

      [ secure validator, other secure validator's public nodes and regular nodes]

      "QmZSocEssLWHYCY6mqR99DcSFEpMb95fVeMsScrY8jqBm8": {
        "enabled": true,
        "endpoint": {
          "listening": {
            "listen_addr": "/ip4/10.0.0.2/tcp/30333",
            "send_back_addr": "/ip4/10.0.0.1/tcp/54932"
          }
        },
        "knownAddresses": [
          "/ip4/10.0.0.1/tcp/30333",
          "/ip4/10.0.1.18/tcp/30333",
          "/ip4/147.75.199.231/tcp/30333",
          "/ip4/10.0.1.152/tcp/30333"
        ],
        "latestPingTime": {
          "nanos": 335876602,
          "secs": 0
        },
        "open": true,
      },
      "QmP3zYRhAxxw4fDf6Vq5agM8AZt1m2nKpPAEDmyEHPK5go": {
        "enabled": true,
        "endpoint": {
          "listening": {
            "listen_addr": "/ip4/172.26.59.86/tcp/30333",
            "send_back_addr": "/ip4/191.232.49.216/tcp/3008"
          }
        },
        "knownAddresses": [
          "/dns4/p2p.testnet-4.kusama.network/tcp/30100",
          "/ip4/127.0.0.1/tcp/30100",
          "/ip4/10.244.0.10/tcp/30100",
          "/ip4/191.232.49.216/tcp/30100"
        ],
        "latestPingTime": {
          "nanos": 603313251,
          "secs": 0
        },
        "open": true,
      },

      [ ........ ]

    },
    "notConnectedPeers": {

      [ regular nodes ]

      "QmW45D6YLfctkSnsjyoqcSxw9qoiXUmAFGn5ea99L6SC7X": {
        "knownAddresses": [
          "/ip4/10.8.2.14/tcp/30101",
          "/ip4/127.0.0.1/tcp/30101",
          "/ip4/34.80.190.48/tcp/30101"
        ],
        "latestPingTime": {
          "nanos": 571989635,
          "secs": 0
        },
      },

      [ ........ ]

    },
    "peerset": {

      [ all known nodes reported as connected here ]

      "QmP3zYRhAxxw4fDf6Vq5agM8AZt1m2nKpPAEDmyEHPK5go": {
        "connected": true,
        "reputation": 1277
      },
      "QmZSocEssLWHYCY6mqR99DcSFEpMb95fVeMsScrY8jqBm8": {
        "connected": true,
        "reputation": -571
      },

      [ ........ ]

      "reserved_only": false
    }
  }
}

Network regular nodes

They can reach and be reached by the validator's public nodes and by other regular nodes, the don't have access to the validator.

{

  [ ........ ]

  "result": {
    "connectedPeers": {

      [ secure validator's public nodes and regular nodes ]

      "QmPjNcWNZjNrjVFzkNYR6jH7HLqyU7j9piczUyNoxce1fD": {
        "enabled": true,
        "endpoint": {
          "listening": {
            "listen_addr": "/ip4/10.44.1.11/tcp/30101",
            "send_back_addr": "/ip4/18.197.157.119/tcp/42962"
          }
        },
        "knownAddresses": [
          "/ip4/172.26.59.86/tcp/30333",
          "/ip4/127.0.0.1/tcp/30333",
          "/ip6/::1/tcp/30333",
          "/ip4/18.197.157.119/tcp/30333",
          "/ip4/10.0.0.2/tcp/30333",
          "/ip4/10.0.1.18/tcp/30333"
        ],
        "latestPingTime": {
          "nanos": 108101687,
          "secs": 0
        },
        "open": true,
      },
      "QmP3zYRhAxxw4fDf6Vq5agM8AZt1m2nKpPAEDmyEHPK5go": {
        "enabled": true,
        "endpoint": {
          "listening": {
            "listen_addr": "/ip4/10.44.1.11/tcp/30101",
            "send_back_addr": "/ip4/191.232.49.216/tcp/3010"
          }
        },
        "knownAddresses": [
          "/dns4/p2p.testnet-4.kusama.network/tcp/30100",
          "/ip4/127.0.0.1/tcp/30100",
          "/ip4/191.232.49.216/tcp/30100",
          "/ip4/10.244.0.10/tcp/30100"
        ],
        "latestPingTime": {
          "nanos": 717286051,
          "secs": 0
        },
        "open": true,
        "versionString": "parity-polkadot/v0.5.0-4e53ad1-x86_64-linux-gnu (unknown)"
      },

      [ ........ ]

    },
    "notConnectedPeers": {

      [ secure validator ]

      "QmZSocEssLWHYCY6mqR99DcSFEpMb95fVeMsScrY8jqBm8": {
        "knownAddresses": [
          "/ip4/10.0.0.1/tcp/30333",
          "/ip4/10.0.1.18/tcp/30333",
          "/ip4/10.0.1.152/tcp/30333",
          "/ip4/147.75.199.231/tcp/30333"
        ],
        "latestPingTime": {
          "nanos": 375552762,
          "secs": 0
        },
      }

      [ ........ ]

    },
    "peerset": {

      [ all known nodes shown here, reported connected to all, secure validator with 0 reputation ]

      "QmP3zYRhAxxw4fDf6Vq5agM8AZt1m2nKpPAEDmyEHPK5go": {
        "connected": true,
        "reputation": 1115
      },
      "QmPjNcWNZjNrjVFzkNYR6jH7HLqyU7j9piczUyNoxce1fD": {
        "connected": true,
        "reputation": 3500
      },
      "QmZSocEssLWHYCY6mqR99DcSFEpMb95fVeMsScrY8jqBm8": {
        "connected": true,
        "reputation": 0
      },

      [ ........ ]

      "reserved_only": false
    }
  }
}

melozo/polkadot-secure-validator