| description |
|---|
Quick steps to secure your node. |
{% hint style="success" %} Thank you for your support and kind messages! It really energizes us to keep creating the best crypto guides. Use cointr.ee to find our donation addresses and share your message. 🙏 {% endhint %}
- Ubuntu Server or Ubuntu Desktop installed
- SSH server installed
- a SSH client or terminal window access
In case you need to install SSH server, refer to:
{% embed url="https://www.simplified.guide/ubuntu/install-ssh-server" %}
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/" %}
{% hint style="info" %} Make a habit of logging to your server using a non-root account. This will prevent the accidental deletion of files if you make a mistake. For instance, the command rm can wipe your entire server if run incorrectly using by a root user. {% endhint %}
{% hint style="warning" %}
****🔥 Tip: Do NOT routinely use the root account. Use su or sudo, always.
{% endhint %}
SSH to your server
ssh [email protected]
# example
# ssh [email protected]Create a new user called cardano
useradd -m -s /bin/bash cardano
Set the password for cardano user
passwd cardano
Add cardano to the sudo group
usermod -aG sudo cardano
{% 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
suorsudo) - Use
sudofor 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.
Your choice of ED25519 or RSA public key algorithm.
{% tabs %} {% tab title="ED25519" %}
ssh-keygen -t ed25519
{% endtab %}
{% tab title="RSA" %}
ssh-keygen -t rsa -b 4096{% endtab %} {% endtabs %}
Transfer the public key to your remote node. Update the keyname.
ssh-copy-id -i $HOME/.ssh/<keyname>.pub [email protected]Login with your new cardano user
Disable root login and password based login. Edit the /etc/ssh/sshd_config file
sudo nano /etc/ssh/sshd_config
Locate ChallengeResponseAuthentication and update to no
ChallengeResponseAuthentication no
Locate PasswordAuthentication update to no
PasswordAuthentication no
Locate PermitRootLogin and update to no
PermitRootLogin no
Locate PermitEmptyPasswords and update to no
PermitEmptyPasswords no
Optional: Locate Port and customize it your random port.
{% hint style="info" %} Use a random port # from 1024 thru 49141. Check for possible conflicts. {% endhint %}
Port <port number>Validate the syntax of your new SSH configuration.
sudo sshd -t
If no errors with the syntax validation, reload the SSH process
sudo service sshd reload
Verify the login still works
{% tabs %} {% tab title="Standard SSH Port 22" %}
{% endtab %}
{% tab title="Custom SSH Port" %}
ssh [email protected] -p <custom port number>{% endtab %} {% endtabs %}
{% hint style="info" %} Alternatively, you might need to use the following.
Add the -p <port#> flag if you used a custom SSH port.
ssh -i <path to your SSH_key_name.pub> [email protected]{% endhint %}
{% 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-get upgrade -y
sudo apt-get autoremove
sudo apt-get autocleanEnable automatic updates so you don't have to manually install them.
sudo apt-get install unattended-upgrades
sudo dpkg-reconfigure -plow unattended-upgrades
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{% 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 follow 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_authenticatorfile: 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 %}
{% 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 %}
{% hint style="warning" %}
There may be a reason for you needing to have that memory space mounted in read/write mode (such as a specific server application like Chrome that requires such access to the shared memory or standard applications like Google Chrome). In this case, use the following line for the fstab file with instructions below.
none /run/shm tmpfs rw,noexec,nosuid,nodev 0 0
The above line will mount the shared memory with read/write access but without permission to execute programs, change the UID of running programs, or to create block or character devices in the namespace. This a net security improvement over default settings.
With some trial and error, you may discover some applications(like Chrome) do not work with shared memory in read-only mode. For the highest security and if compatible with your applications, it is a worthwhile endeavor to implement this secure shared memory setting.
Source: techrepublic.com {% endhint %}
Edit /etc/fstab
sudo nano /etc/fstab
Insert the following line to the bottom of the file and save/close.
tmpfs /run/shm tmpfs ro,noexec,nosuid 0 0
Reboot the node in order for changes to take effect.
sudo reboot
{% 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.
# Exampleignoreip = 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
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.
- Port 22 (or your random port #) TCP for SSH connection
- Port 6000 TCP for p2p traffic
- Port 3000 TCP for Grafana web server (if hosted on current node)
- Port 9090 tcp for Prometheus export data (optional, if hosted on current node)
ufw allow <22 or your random port number>/tcp
ufw allow 6000/tcp
ufw allow 3000/tcp
ufw enable
ufw status numbered{% hint style="danger" %} Do not expose Grafana (port 3000) and Prometheus endpoint (port 9090) to the public internet as this invites a new attack surface! A secure solution would be to access Grafana through a ssh tunnel with Wireguard. {% endhint %}
Only open the following ports on nodes behind a network firewall.
****🔥 It is dangerous to open these ports on a VPS/cloud node.
sudo ufw allow 3000/tcp
sudo ufw allow 9090/tcpConfirm the settings are in effect.
To Action From -- ------ ---- [ 1] 22/tcp ALLOW IN Anywhere [ 2] 3000/tcp ALLOW IN Anywhere [ 3] 6000/tcp ALLOW IN Anywhere [ 4] 22/tcp (v6) ALLOW IN Anywhere (v6) [ 5] 3000/tcp (v6) ALLOW IN Anywhere (v6) [ 6] 6000/tcp (v6) ALLOW IN Anywhere (v6)
[ Optional but recommended ] Whitelisting (or 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{% hint style="info" %} 🎊 Port Forwarding Tip: You'll need to forward and open ports to your validator. Verify it's working with https://www.yougetsignal.com/tools/open-ports/ or https://canyouseeme.org/ . {% endhint %}
If you want to maintain a secure server, you should validate the listening network ports every once in a while. This will provide you essential information about your network.
netstat -tulpn
ss -tulpn
{% hint style="success" %} Congrats on completing the guide. ✨
Did you find our guide useful? Send us a signal with a tip and we'll keep updating it.
It really energizes us to keep creating the best crypto guides.
Use cointr.ee to find our donation addresses. 🙏
Any feedback and all pull requests much appreciated. 🌛
Hang out and chat with fellow stake pool operators on Discord @
https://discord.gg/w8Bx8W2HPW 😃
Hang out and chat with our stake pool community on Telegram @ https://t.me/coincashew {% endhint %}
{% embed url="https://medium.com/@BaneBiddix/how-to-harden-your-ubuntu-18-04-server-ffc4b6658fe7" %}
{% embed url="https://linux-audit.com/ubuntu-server-hardening-guide-quick-and-secure/" %}
{% embed url="https://www.digitalocean.com/community/tutorials/how-to-harden-openssh-on-ubuntu-18-04" %}
{% embed url="https://ubuntu.com/tutorials/configure-ssh-2fa\#1-overview" %}
https://gist.github.com/lokhman/cc716d2e2d373dd696b2d9264c0287a3#file-ubuntu-hardening-md
{% embed url="https://www.lifewire.com/harden-ubuntu-server-security-4178243" %}
{% embed url="https://www.ubuntupit.com/best-linux-hardening-security-tips-a-comprehensive-checklist/" %}