🗝️Troubleshoot SSH Connection

Introduction

This guide is designed to help you troubleshoot and restore SSH access to your Validator node when it was previously working but is now unreachable.

♻️How to SSH into VPS

Common Steps

✅ Verify the username for the VPS you're connecting to

  • e.g.) nodeadmin

✅ Check your SSH key pair file names

  • Private key must match the server's authorized key.

✅ Confirm correct permissions

  • private key should be read-only: chmod 400

✅ Ensure the public key exists on the server in the correct location

✅ Confirm the private key file exists locally

  • Is it correctly referenced by your SSH command.


🏠 Local IP address

Many ISPs assign dynamic IP addresses to customer routers.

A change in your IP may cause your cloud provider’s firewall to block your SSH attempts.

🩹Symptoms:

Your SSH terminal or remote connection application sits idle and eventually shows Connection timed out messages.

Terminal or remote terminal application will how a blank screen only

No password or key prompts appear

Not entering the SSH connection string and attempting to run commands locally instead of through your SSH tunnel.

💡 Example:

ssh -i ~/.ssh/my_identity_file [email protected]
ssh: connect to host 13.13.13.13 port 22: Operation timed out

🔧 How to Fix It

1

Determine your new IP address

Open your web browser and navigate to:

2

Record New IP Address

Copy your current public IPv4 address

3

Cloud Provider Console

Go to your cloud provider's web console.

4

Update Firewall Rules

Update your firewall or security group rules to allow SSH access from your new IP

  • AWS: Update the Security Group

  • DigitalOcean: Update Firewall settings

  • Hetzner: Follow DigitalOcean-style firewall update workflow

Try connecting again after updating the rules.


🔐 SSH Key Issues

📍 Local Key Issues

Ensure the private key file:

  • Still exists in the expected location

  • Has not been renamed or moved

  • Is intact and not corrupted

  • Has the proper permissions

📌 Tip:

If in doubt, restore your key from a known-good backup.

Important: Once resolved, create a backup of your SSH keys if you haven’t already.


📡 Remote Key Issues (Accessing via Console)

If you can still access your VPS through your cloud provider's web console:

1

Log into the Web Terminal

2
cd ~/.ssh
ls -l
3

Verify Public Key

Check for the authorized public key file

authorized_keys or .pub file.

If the key is missing or incorrect:

Check alternate directories:

ls -l /root/.ssh/
ls -l /home/ubuntu/.ssh/
ls -l /home/admin/.ssh/
4

Identify _backup

If you find your key with a _backup attached to the name of the file, issue the following command and check again:

Enable root SSH temporarily:

sudo nodectl enable_root_ssh
5

Copy SSH Key Back Over

Copy the key into your nodeadmin’s .ssh directory :

sudo cp /root/.ssh/mypublickey.pub /home/nodeadmin/.ssh/mypublickey.pub

Change ownership

sudo chown nodeadmin:nodeadmin /home/nodeadmin/.ssh/mypublickey.pub
6

Disable Root Access Again

sudo nodectl disable_root_ssh

Re-Attempt to create an SSH connection to your node.


📡 Cloud Provider Outage

  • Visit your cloud provider’s main dashboard

  • Look for service alerts

  • If the console is also unreachable, check external outage reports


🖥️ VPS-Specific Issue

  • From the cloud console, check the status of your VPS instance

  • Ensure it’s running and not reporting hardware or OS-level errors


🌍 Local Internet Outage

  • If you cannot connect to any external site or service, confirm your own network is online

  • Restart your router/modem if necessary and try again later

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