Intermediate

Network Configuration for A Core Cell

Welcome to our tutorial on network configuration for a Core Cell on the Klaytn blockchain network. In Klaytn, Core Cells are responsible for maintaining the integrity of the blockchain by validating transactions and producing blocks. In order for a Core Cell to function properly, it must be properly configured to connect to and communicate with the rest of the network. In this tutorial, we will explore the process of configuring a Core Cell on the Klaytn network, including the necessary network settings, the process of registering the Core Cell on the network, and best practices for ensuring network stability and security. Whether you are a developer, researcher, or simply a blockchain enthusiast, this tutorial will provide valuable insights and hands-on experience in configuring a Core Cell on the Klaytn network.

A Core Cell can be made up of:

• multiple subnets (recommended)

• a single subnet

A Core Cell with Multiple Subnets

It is recommended to have a two-layer subnet which is used in general web services such as DB + AppServer and Proxy Web Servers. This design of the subnet has more advantages in security.

Since monitoring servers are also required for managing all servers as another layer, the following section describes how to set up a Core Cell with a three-layer subnet.

The three-layer subnet consists of the following:

• CN Subnet

• PN Subnet

• Management (Mgmt) Subnet

CN Subnet

A CN Subnet consists of CN servers in Core Cells. The working CN in a Core Cell is only one, but a spare one should be prepared for high availability. IP/Port of all CNs within the Core Cell Network (CCN) must be opened to each other because they try to connect to the others from the outside of the Core Cell. (This connection information can be received from Baobab operators.) The internal communication with other subnets in the Core Cell requires opening the default port (32323: default Klaytn P2P port number) in order to connect to the PNs of the PN Subnet. Furthermore, it is necessary to open other ports such as the CN monitoring port (61001) for the monitoring server and the SSH port (22) for the management purpose. If the multichannel feature is used, another port (32324: default multichannel port) should be opened as well.

CN Subnet

 

Origin Subnet	Target Subnet	Ingress	Egress
CN Subnet	PN Subnet	P2P: 32323 (32324 for multichannel)	All
CN Subnet	Mgmt Subnet	SSH: 22, Monitoring: 61001	All
CN Subnet	Public (Internet)	each CN’s IP and P2P port	All

 

PN Subnet

A PN Subnet consists of the PN servers to provide services in order to connect to the external ENs.

A PN subnet is connected to the following nodes:

• CNs in Core Cells

• Some PNs of other Core Cells

• Core Cell Management Servers (Mgmt, Monitoring)

• EN nodes

PN Subnet

 

 

Origin Subnet	Target Subnet	Ingress	Egress
PN Subnet	CN Subnet	P2P: 32323 (32324 for multichannel)	All
PN Subnet	Mgmt Subnet	SSH: 22, Monitoring: 61001	All
PN Subnet	Public (Internet)	P2P: 32323	All

 

Mgmt Subnet

An Mgmt Subnet is a gateway subnet for the operator to enter into the Core Cell nodes through ssh. A VPN server may be necessary to make the connection together with a monitoring server and a management server installed with a tool to manage the Core Cell nodes.

Management Subnet

 

 

Origin Subnet	Target Subnet	Ingress	Egress
Mgmt Subnet	CN Subnet	All	All
Mgmt Subnet	PN Subnet	All	All
Mgmt Subnet	Public (Internet)	VPN (tcp): 443, VPN (udp): 1194	All

A Core Cell with a Single Subnet

A single subnet of a Core Cell is built for the development/test purpose or under difficult circumstances to create multiple subnets.

All nodes are set up under a single CC subnet. A firewall setup is also necessary for the CN to connect to other CNs within the CNN using the P2P port (32323, 32324 for the multichannel option). The P2P port of the PN is opened to connect with ENs in Endpoint Node Network (ENN) and PNs in the Core Cell Network (CNN). Additionally, an optional VPN and monitoring servers are required to be managed remotely.

Before You Install

Before installing the Klaytn package, it is required to create the associated node information to enroll your node URIs. The Kgen package is provided for CC operators, please follow the steps in the order shown below.

1. Download kgen Package

2. Node Key & Node URI Creation

3. Node URI Enrollment

Download kgen Package

First of all, you can download the latest version of kgen package depending on your operating system on the Download page.

You can find the kgen binary file under the bin directory.

Node Key & Node URI Creation

The node key and the node URI are created only once at the beginning. The node URI must be shared with other Core Cells of the Core Cell Network. A CN connects to other CNs and a PN connects to a CN and some PNs using the created node URI. A node URI is created based on the node key by using the downloaded kgen. The below command line creates nodekey as well as node_info.json.

kgen takes the associated IP and Port number as follows.

$ kgen --ip "123.456.789.012" --port 32323 --file

$ ls

nodekey node_info.json

The nodekey is a 64-byte hexadecimal string which is a private key used in the node internally. This private key must be present in the Klaytn data directory and be careful not to lose it.

$ cat nodekey

f08f2118c455a6c9c9b5e035d3571e570a719ea61771e268546e796a264acc2b

$ mv nodekey ~/kcnd_home

The created file node_info.json includes the following contents.

 

Key Name	Description	Example
NodeAddress	an address of the associated node	0xc8a23d67f2471066fa1b07270651fea7e5c0cf78
NodeKey	the node key (a.k.a private key)	aaa7248dfdf19418ae9121a0f39db39c5c27a3e404ea7c1b8e020ca8dbe7e71a
NodeURI	node URI	kni://4f2f47f3bf35a2c576d3345e6e9c49b147d510c05832d2458709f63c3c90c76ead205975d944ed65e77dd4c6f63ebe1ef21d60da95952bc1e200e7487f4d9e1b@123.456.789.012:32323?discport=0

node_info.json contains the node information in a JSON format as follows.

$ cat node_info.json
{

    "NodeAddress": "0xc8a23d67f2471066fa1b07270651fea7e5c0cf78",

    "NodeKey": "aaa7248dfdf19418ae9121a0f39db39c5c27a3e404ea7c1b8e020ca8dbe7e71a",

    "NodeURI": "kni://4f2f47f3bf35a2c576d3345e6e9c49b147d510c05832d2458709f63c3c90c76ead205975d944ed65e77dd4c6f63ebe1ef21d60da95952bc1e200e7487f4d9e1b@123.456.789.012:32323?discport=0"

}

Node URI Enrollment

The created node URI should be enrolled to participate in the Core Cell Network (CCN). The process of enrollment is as follows.

1. Create a node URI using kgen (node_info.json) which contains the associated IP and Port number.

2. Send the information to the official Klaytn email address (bootstrap@klaytn.com for Cypress or baobab@klaytn.com for Baobab).

The enrolled information should be sent to the official Klaytn email address. The format is as follows.

In the case of CN,

Company: Kakao
CN URI : kni://
4f2f47f3bf35a2c576d3345e6e9c49b147d510c05832d2458709f63c3c90c76ead205975d944ed65e77dd4c6f63ebe1ef21d60da95952bc1e200e7487f4d9e1b@123.456.789.012:32323?discport=0

In the case of PN,

Company: Kakao
PN URI : kni://
4f2f47f3bf35a2c576d3345e6e9c49b147d510c05832d2458709f63c3c90c76ead205975d944ed65e77dd4c6f63ebe1ef2

With this, you complete this workshop successfully!!

 

 

 

Units of KLAY

Klaytn uses the following unit system for KLAY.

• peb is the smallest currency unit.

• ston is an alias for Gpeb and was introduced for convenience.

• A KLAY is 10^18 peb.

APIs Related to KLAY Units

klay.toPeb and klay.fromPeb are convenient APIs for converting between KLAY units.

$ ./klay attach data/dd/klay.ipc
...
> klay.fromPeb(25, "peb")
"25"
> klay.fromPeb(25, "Gpeb")
"0.000000025"
> klay.fromPeb(25, "ston")
"0.000000025"
> klay.fromPeb(25, "KLAY")
"0.000000000000000025"
> klay.toPeb(25, "peb")
"25"
> klay.toPeb(25, "ston")
"25000000000"
> klay.toPeb(25, "KLAY")
"25000000000000000000"

> klay.toPeb(1, "something-does-not-exist")
Error: This unit doesn't exist, please use one of the following units
"noKLAY": "0"
"peb": "1"
"kpeb": "1000"
"Mpeb": "1000000"
"Gpeb": "1000000000"
"ston": "1000000000"
"uKLAY": "1000000000000"
"mKLAY": "1000000000000000"
"KLAY": "1000000000000000000"
"kKLAY": "1000000000000000000000"
"MKLAY": "1000000000000000000000000"
"GKLAY": "1000000000000000000000000000"
"TKLAY": "1000000000000000000000000000000"

    at web3.js:2170:19
    at web3.js:2255:49
    at <anonymous>:1:1