Read the article to more about the troubleshooting of error “kex_exchange_identification connection closed by remote host.” As part of our Server Management Service, Bobcares provides answers to all of your questions.

Overview

1. What is meant by the error “kex_exchange_identification connection closed by remote host”?
2. Error Causes
3. Troubleshooting Tips

What is meant by the error “kex_exchange_identification connection closed by remote host”?

This error message usually means that the server ended the SSH connection—the first stage in creating an SSH connection—during the key exchange procedure. Several factors may lead to this. Let’s look into the details.

Error Causes

1. Network Issues: Disruptions like high latency, packet loss, or firewall blocks can prevent the SSH handshake from completing.

2. SSH Server Configuration: Misconfigured server settings, such as MaxStartups in sshd_config, can limit connections and cause drops.

3. SSH Client Configuration: Incorrect client settings (e.g., hostname, port, or authentication method) can fail to establish a connection. Ensure they match the server’s requirements.

4. Key Permissions: Incorrect SSH key permissions can cause issues. Set private key permissions to 0600 with chmod 0600 .

5. Security Measures: Servers may close connections if they detect insecure settings or unsupported encryption algorithms.

6. Proxy and VPN Issues: Proxies or VPNs can interfere with SSH connections. Disabling or adjusting their settings may help.

Troubleshooting Tips

To resolve the kex_exchange_identification problem, take into account the steps listed below:

1. Verify Network Connectivity: Make sure that the SSH port—typically port 22—is not being blocked by firewalls and that the internet connection is steady.

2. Examine server setup: If we are able to log in to the server, make sure that all the settings are correct. Pay particular attention to the MaxStartups and Allowed Users sections of the sshd_config file.

3. Verify Client Config: Look for typos or improper settings in the SSH command and configuration files by double-checking them.

4. Modify Key Permissions: Verify that the right permissions are assigned to the SSH keys.

5. Test Without Proxy/VPN: If the problem persists, try connecting without a proxy or VPN if we are using one.

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Conclusion

This article offers a brief insight into the error “kex_exchange_identification connection closed by remote host.” To sum up, our Support Team went over the troubleshooting details.