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Node Endpoints

As specified in the Network Requirements, a Casper node uses specific ports to communicate with client applications and other nodes on the network. Each node has an identity linked with an IP and port pair where the node is reachable. This address is also called an endpoint. The Network Communication page explains how the nodes connect and communicate securely. Node connections are established using TLS, presenting a client certificate to encrypt peer-to-peer communication.

This document describes in more detail a Casper node's default endpoints:

Node operators can modify a node's configuration options, including the port settings, by updating the node's config.toml file. An example configuration file can be found here.

The default endpoints for Mainnet and Testnet are open by default and are described below in more detail. If the node connects to a different network, the ports may differ depending on how the network was set up.

Default Networking Port: 35000​

The configuration options for networking are under the network section of the config.toml file. The bind_address using port 35000 is the only port required to be open for the node to function. A Casper node taking part in the network should open connections to every other node it is aware of and has not blocked. In the config.toml file, the setting is:

bind_address = '0.0.0.0:35000'

If the networking port is closed, the node becomes unreachable, and the node won't be discoverable in the network. If this is a validator, it will face eviction. A read-only node will be considered to be offline.

Default JSON-RPC HTTP Server Port: 7777​

The configuration options for the JSON-RPC HTTP server are under the rpc_server section in the config.toml file. The address using port 7777 is the listening address for JSON-RPC HTTP server.

address = '0.0.0.0:7777'

DApps would use this address to interact with the Casper JSON-RPC API. Users would use this address to interact with the network using CLI. Validators would use this address to bond or unbond. If this port is closed, the requests coming to this port will not be served, but the node remains unaffected.

Default REST HTTP Server Port: 8888​

The configuration options for the JSON-RPC HTTP server are under the rest_server section in the config.toml file. The address listing port 8888 is the listening address for the REST HTTP server.

address = '0.0.0.0:8888'

Opening port 8888 is recommended but not required. This port allows the node to be included in the general network health metrics, thus giving a more accurate picture of overall network health. If this port is closed, the requests coming to this port will not be served, but the node remains unaffected.

One may use this port to get a trusted hash, verify successful staging during an upgrade, or to confirm that the node is synchronized.

Example usage​

For general health metrics, use this command:

curl -s http://<node_address>:8888/metrics

You can check the node's status using this command:

curl -s http://<node_address>:8888/status

The status endpoint provides a JSON response that can be parsed with jq.

curl -s http://<node_address>:8888/status | jq
Sample response
{
    "api_version": "1.4.15",
    "chainspec_name": "casper-test",
    "starting_state_root_hash": "4c3856bd6a95b566301b9da61aaf84589a51ee2980f3cc7bbef78e7745386955",
    "peers": [
        {
            "node_id": "tls:007e..e14b",
            "address": "89.58.52.245:35000"
        },
        {
            "node_id": "tls:00eb..ac11",
            "address": "65.109.17.120:35000"
        },
        ...{
            "node_id": "tls:ffc0..555b",
            "address": "95.217.228.224:35000"
        }
    ],
    "last_added_block_info": {
        "hash": "7acd2f48b573704e96eab54322f7e91a0624252baca3583ad2aae38229fe1715",
        "timestamp": "2023-05-10T09:20:10.752Z",
        "era_id": 9085,
        "height": 1711254,
        "state_root_hash": "1ac74071c1e76937c372c8d2ae22ea036a77578aad03821ec98021fdc1c5d06b",
        "creator": "0106ca7c39cd272dbf21a86eeb3b36b7c26e2e9b94af64292419f7862936bca2ca"
    },
    "our_public_signing_key": "0107cba5b4826a87ddbe0ba8cda8064881b75882f05094c1a5f95e957512a3450e",
    "round_length": "32s 768ms",
    "next_upgrade": null,
    "build_version": "1.4.15-039d438f2-casper-mainnet",
    "uptime": "5days 13h 46m 54s 520ms"
}

You can filter the result with dot notation, specifying one of the following parameters:

  • api_version - The RPC API version
  • chainspec_name - The chainspec name, used to identify the currently connected network
  • starting_state_root_hash - The state root hash used at the start of the current session
  • peers - The node ID and network address of each connected peer
  • last_added_block_info - The minimal info of the last Block from the linear chain
  • our_public_signing_key - Our public signing key
  • round_length - The next round length if this node is a validator.
  • next_upgrade - Information about the next scheduled upgrade
  • build_version - The compiled node version
  • uptime - Time that has passed since the node has started.

Here is an example command for retrieving general network information:

curl -s http://<node_address>:8888/status | jq -r '.api_version, .last_added_block_info, .build_version, .uptime'
Sample response
"1.4.15"
{
  "hash": "dca9959b21df52633f85cd373a8117fe8e89629dd2a0455781484a439f7d9f62",
  "timestamp": "2023-05-10T09:26:43.968Z",
  "era_id": 9085,
  "height": 1711266,
  "state_root_hash": "5f374529e747a06ec825e07a030df7b9d80d1f7ffac9156779b4466620721872",
  "creator": "0107cba5b4826a87ddbe0ba8cda8064881b75882f05094c1a5f95e957512a3450e"
}
"1.4.15-039d438f2-casper-mainnet"
"5days 13h 53m 10s 763ms"

To get information about the next upgrade, use:

curl -s http://<node_address>:8888/status | jq .next_upgrade

To get information about the last added block, use:

curl -s http://<node_address>:8888/status | jq .last_added_block_info

To monitor the downloading of blocks to your node:

watch -n 15 'curl -s http://<node_address>:8888/status | jq ".peers | length"; curl -s http://<node_address>:8888/status | jq .last_added_block_info'

To monitor local block height as well as RPC port status:

watch -n 15 'curl -s http://<node_address>:8888/status | jq ".peers | length"; curl -s http://<node_address>:8888/status | jq .last_added_block_info; casper-client get-block -n http://<node_address>:8888/status'

Default SSE HTTP Event Stream Server Port: 9999​

The configuration options for the SSE HTTP event stream server are listed under the event_stream_server section of the config.toml file. The address listing port 9999 is the listening address for the SSE HTTP event stream server.

address = '0.0.0.0:9999'

If this port is closed, the requests coming to this port will not be served, but the node remains unaffected. For details and useful commands, see Monitoring and Consuming Events.

Setting up Firewall Rules​

To limit inbound traffic to the node’s endpoints, you can set firewall rules similar to the ufw commands below:

sudo apt install ufw -y
sudo ufw disable
sudo ufw reset
sudo ufw default allow outgoing
sudo ufw default deny incoming
sudo ufw limit ssh
sudo ufw limit 7777/tcp
sudo ufw limit 8888/tcp
sudo ufw limit 35000/tcp
sudo ufw enable

These commands will limit requests to the available ports of your node. Port 35000 should be left open, although you can limit traffic, as it is crucial for node-to-node communication.

If you have any concerns, questions, or issues, please submit a request to the Casper support team.

Restricting Access for Private Networks​

Any node can join Mainnet and Testnet and communicate with the nodes in the network. Private networks may wish to restrict access for new nodes joining the network as described here.

Here is a summary of the links mentioned on this page:

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