Instructions on how to run a Full Node, Validator Node, and RPC Services for KalyChain.

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Quick steps to secure your node.

Security Best Practices for your Validator node

Completing this guide will provide a solid baseline to protect and secure your node.

🤖 Pre-requisites

Operating System: Ubuntu 20.04 LTS 64 bits

Hardware:

Hardware	minimum	desired
CPU's:	2	4
Memory:	4 Gb	8 Gb
Hard Disk:	100 Gb	1000 Gb

a SSH client or terminal window access on a local computer.

In case you need a SSH client for your operating system, refer to:

{% embed url="https://www.howtogeek.com/311287/how-to-connect-to-an-ssh-server-from-windows-macos-or-linux/" %}

:man_mage: Mandatory: Create a non-root user with sudo privileges

Begin by connecting to your Ubuntu Server with your SSH client.

ssh root@node.ip.address

Create a new user called kaly

sudo useradd -m -s /bin/bash kaly

{% hint style="info" %} the user name kaly is only an example you can make any user name you wish {% endhint %}

Set the password for kaly user

sudo passwd kaly

Add kaly to the sudo group

sudo usermod -aG sudo kaly

🔐 Mandatory: Disable SSH password Authentication and Use SSH Keys only

{% hint style="info" %} The basic rules of hardening SSH are:

No password for SSH access (use private key)
Don't allow root to SSH (the appropriate users should SSH in, then su or sudo)
Use sudo for users so commands are logged
Log unauthorized login attempts (and consider software to block/ban users who try to access your server too many times, like fail2ban)
Lock down SSH to only the ip range your require (if you feel like it) {% endhint %}

Create a new SSH key pair on your local machine. Run this on your local machine. You will be asked to type a file name in which to save the key. This will be your keyname.

ssh-keygen -t ed25519

Your SSH key pair is stored in your home directory. For example, if your keyname was mySSHkey, then your private SSH key is mySSHkey and your public SSH key is mySSHkey.pub

{% hint style="warning" %} IMPORTANT: Make multiple backup copies of your private SSH key file to external storage, such as a USB backup key, for recovery purposes.

Verify the contents of your private SSH key file before moving on.

cat <keyname>

It should look similar to this example.

{% endhint %}

Transfer the public key to your remote node. Replace <keyname.pub> appropriately.

ssh-copy-id -i $HOME/<keyname.pub> kaly@node.ip.address

ssh kaly@node.ip.address

Disable root login and password based login. Edit the /etc/ssh/sshd_config file

sudo nano /etc/ssh/sshd_config

Locate PubkeyAuthentication and update to yes. Delete the #, if needed.

PubkeyAuthentication yes

Locate PasswordAuthentication and update to no

PasswordAuthentication no

Locate PermitRootLogin and update to prohibit-password

PermitRootLogin prohibit-password

Locate PermitEmptyPasswords and update to no

PermitEmptyPasswords no

Optional: Locate Port and customize it your random port.

Port <your random port number>

{% hint style="info" %} A valid random port # ranges from 1024 thru 49141.

Check that the port is not already used by other services. Replace <port> with your random port #.

sudo ss -ntlp | grep :<port>

Empty response means the port is good.

A response with red numbers means the port is already used. Choose another port. {% endhint %}

Validate the syntax of your new SSH configuration.

sudo sshd -t

If no errors with the syntax validation, restart the SSH process

sudo systemctl restart sshd

Verify the login still works

{% tabs %} {% tab title="Standard SSH Port 22" %}

ssh kaly@node.ip.address

{% endtab %}

{% tab title="Custom SSH Port" %}

ssh kaly@node.ip.address -p <custom random port number>

{% endtab %} {% endtabs %}

Optional: Make logging in easier by updating your local ssh config.

To simplify the ssh command needed to log in to your server, consider updating your local $HOME/.ssh/config file:

Host kaly-node
  User kaly
  HostName <node.ip.address>
  Port <custom random port number>

This will allow you to log in with ssh kaly-node rather than needing to pass through all ssh parameters explicitly.

🤖 Mandatory: Update your system

{% hint style="warning" %} It's critically important to keep your system up-to-date with the latest patches to prevent intruders from accessing your system. {% endhint %}

sudo apt-get update -y && sudo apt dist-upgrade -y
sudo apt-get autoremove
sudo apt-get autoclean

Enable automatic updates so you don't have to manually install them.

sudo apt-get install unattended-upgrades
sudo dpkg-reconfigure -plow unattended-upgrades

Reboot your system to enable the upgrades.

sudo reboot

🧱 Mandatory: Configure your Firewall

The standard UFW firewall can be used to control network access to your node.

With any new installation, ufw is disabled by default. Enable it with the following settings.

If you used a custom random SSH port, replace "22" with your actual port #.

# By default, deny all incoming and outgoing traffic
sudo ufw default deny incoming
sudo ufw default allow outgoing
# Allow ssh access
sudo ufw allow 22/tcp
# Allow execution client port
sudo ufw allow 30303
# Allow rpc port
sudo ufw allow 8545
# Allow ws port
sudo ufw allow 8546
# Enable firewall
sudo ufw enable

{% hint style="warning" %} If you dont want to make RPC or WS calls to your node remotely Omit allowing ports 8545 and 8546. {% endhint %}

Confirm the settings are in effect.

sudo ufw status numbered

Example of properly configured ufw status for Lighthouse.

     To                         Action      From
     --                         ------      ----
[ 1] 22/tcp                     ALLOW IN    Anywhere
[ 2] 30303                      ALLOW IN    Anywhere
[ 3] 8545                       ALLOW IN    Anywhere
[ 4] 8546                       ALLOW IN    Anywhere
[ 5] 22/tcp (v6)                ALLOW IN    Anywhere (v6)
[ 6] 30303 (v6)                 ALLOW IN    Anywhere (v6)
[ 7] 8545 (v6)                  ALLOW IN    Anywhere (v6)
[ 7] 8546 (v6)                  ALLOW IN    Anywhere (v6)

{% hint style="warning" %} Note for Grafana Users: Do not expose Grafana (port 3000) to the public internet as this invites a new attack surface! A secure solution would be to access Grafana through a ssh tunnel.

Example of how to create a ssh tunnel:

ssh -N -v kaly@node.ip.address -L 3000:localhost:3000

{% endhint %}

[ Optional ] Whitelisting, which means permitting connections from a specific IP, can be setup via the following command.

sudo ufw allow from <your local daily laptop/pc>
# Example
# sudo ufw allow from 192.168.50.22

⛓️ Mandatory: Install Fail2ban

{% hint style="info" %} Fail2ban is an intrusion-prevention system that monitors log files and searches for particular patterns that correspond to a failed login attempt. If a certain number of failed logins are detected from a specific IP address (within a specified amount of time), fail2ban blocks access from that IP address. {% endhint %}

sudo apt-get install fail2ban -y

Edit a config file that monitors SSH logins.

sudo nano /etc/fail2ban/jail.local

Add the following lines to the bottom of the file.

{% hint style="info" %} 🔥 Whitelisting IP address tip: The ignoreip parameter accepts IP addresses, IP ranges or DNS hosts that you can specify to be allowed to connect. This is where you want to specify your local machine, local IP range or local domain, separated by spaces.

# Example
ignoreip = 192.168.1.0/24 127.0.0.1/8

{% endhint %}

[sshd]
enabled = true
port = <22 or your random port number>
filter = sshd
logpath = /var/log/auth.log
maxretry = 3
# whitelisted IP addresses
ignoreip = <list of whitelisted IP address, your local daily laptop/pc>

Save/close file.

Restart fail2ban for settings to take effect.

sudo systemctl restart fail2ban

🐻 Optional: Disable root account

System admins should not frequently log in as root in order to maintain server security. Instead, you can use sudo execute that require low-level privileges.

# To disable the root account, simply use the -l option.
sudo passwd -l root

# If for some valid reason you need to re-enable the account, simply use the -u option.
sudo passwd -u root

:tools: Optional: Setup Two Factor Authentication for SSH

{% hint style="info" %} SSH, the secure shell, is often used to access remote Linux systems. Because we often use it to connect with computers containing important data, it’s recommended to add another security layer. Here comes the two factor authentication (2FA). {% endhint %}

sudo apt install libpam-google-authenticator -y

To make SSH use the Google Authenticator PAM module, edit the /etc/pam.d/sshd file:

sudo nano /etc/pam.d/sshd

Add the following line:

auth required pam_google_authenticator.so

Now you need to restart the sshd daemon using:

sudo systemctl restart sshd.service

Modify /etc/ssh/sshd_config

sudo nano /etc/ssh/sshd_config

Locate ChallengeResponseAuthentication and update to yes

ChallengeResponseAuthentication yes

Locate UsePAM and update to yes

UsePAM yes

Save the file and exit.

Run the google-authenticator command.

google-authenticator

It will ask you a series of questions, here is a recommended configuration:

Make tokens “time-base”": yes
Update the .google_authenticator file: yes
Disallow multiple uses: yes
Increase the original generation time limit: no
Enable rate-limiting: yes

You may have noticed the giant QR code that appeared during the process, underneath are your emergency scratch codes to be used if you don’t have access to your phone: write them down on paper and keep them in a safe place.

Now, open Google Authenticator on your phone and add your secret key to make two factor authentication work.

{% hint style="danger" %} Note: If you are enabling 2FA on a remote machine that you access over SSH you need to follow steps 2 and 3 of this tutorial to make 2FA work. {% endhint %}

🧩 Optional: Secure Shared Memory

{% hint style="info" %} One of the first things you should do is secure the shared memory used on the system. If you're unaware, shared memory can be used in an attack against a running service. Because of this, secure that portion of system memory.

To learn more about secure shared memory, read this techrepublic.com article. {% endhint %}