How to Fix ssh_exchange_identification read Connection reset by peer Error?

Introduction

Secure Shell (SSH) is a protocol utilized for secure network communication. SSH is significant for organizations of all sizes as it provides secure remote access to servers and computers across unsecured networks.

With its ability to encrypt data, SSH ensures that the information being exchanged between two endpoints remains confidential, even if the data is transmitted over a public network like the internet. SSH has become the de-facto standard for most system administrators when remotely accessing their servers as compared to other protocols like Telnet and FTP that transmit data in plain text which makes it vulnerable to interception or eavesdropping attacks.

Therefore, it’s crucial to keep your SSH server up-to-date with the latest security patches and configurations. It also means that any error or connectivity issue on an SSH connection needs immediate attention.

Understanding the Error

When working with SSH, there may be a common error that can cause frustration and confusion: the ssh_exchange_identification read Connection reset by peer error. This error message indicates that there is a problem with the SSH connection between your client and server, and it can prevent you from accessing your server or running commands remotely. It is important to understand this error message and its potential causes in order to quickly resolve it.

Definition of ssh_exchange_identification read Connection reset by peer error

The ssh_exchange_identification read Connection reset by peer error typically occurs when you are trying to establish an SSH connection to a remote server. The "ssh_exchange_identification" refers to the process where both the client and server exchange identification information during the initial connection setup.

The "Connection reset by peer" part of this error message means that the server abruptly ended or terminated the connection while attempting to identify itself, without sending back any identifying information.

Causes of the Error

Network Issues

In some cases, network connectivity issues can cause this type of error. For example, if there is high network traffic or instability causing packet loss or delay, SSH connections may be affected. Additionally, if you are connecting from behind a proxy or router which does not allow outgoing SSH traffic, then you will not be able to establish an SSH connection with your remote server.

Firewall Restrictions

If your remote server has firewall restrictions in place that block incoming SSH traffic on certain ports (usually port 22), then you will not be able to establish an SSH connection with it. Make sure that any firewalls in use are properly configured to allow incoming and outgoing SSH traffic on these needed ports.

Incorrect SSH Configuration

The ssh_exchange_identification read Connection reset by peer error can also be caused by incorrect SSH configuration settings. This can happen if the SSH server is not properly configured to allow incoming connections from your IP address or if the SSH client is configured to use the wrong authentication credentials.

Another potential cause for incorrect SSH configuration is a mismatch between the encryption algorithms used on both the client and server. If these mismatch, it may cause a handshake failure, which in turn results in ssh_exchange_identification read Connection reset by peer error.

Troubleshooting Steps to Fix the Error

Step-by-step guide on how to fix ssh_exchange_identification read Connection reset by peer error

When encountering ssh_exchange_identification read Connection reset by peer error, it is essential to follow a systematic method of troubleshooting. The following are the step-by-step instructions on fixing the error −

• Check network connectivity −In most cases, the error occurs due to poor network connectivity. Therefore, it is crucial to verify that both devices can communicate with each other.

  To check connectivity, ping from one device to another and ensure that there are no packet losses.

• Disable firewall temporarily −If you have verified that there are no network issues, disable your firewall temporarily and attempt connecting again.

  A firewall can block SSH connections or cause interference in communication between devices.

• Verify SSH configuration settings −It is essential to check if your SSH configuration settings match those on the server-side as misconfiguration could be the cause of this error.

Checking Network Connectivity

As noted earlier, weak or failed connections can cause ssh_exchange_identification read Connection reset by peer errors. Checking network connectivity is relatively straightforward as it involves pinging from one device's command prompt or terminal window and verifying that packets are delivered successfully without any packet loss.

To ping your device using a command prompt window in Windows OS −

• Click "Start"

• Type "cmd" in the search box

• Right-click on "Command Prompt" and select "Run as administrator"

• Type "ping " and press Enter Replace "" with either an IP address or hostname of another device with which you want to test connectivity.

If successful, you should see a message indicating replies received successfully (without packet loss). If unsuccessful, troubleshoot further using other available resources from your IT team or internet searches!

Disabling Firewall Temporarily

A firewall can cause interference in communication between two devices or block SSH connections altogether. Suppose the troubleshooting process identifies that the network connection is not to blame for the error. In that case, it might be necessary to disable the firewall temporarily and attempt to connect again.

To disable a firewall on a Windows 10 operating system −

• Click "Start"

• Type "Windows Security" in the search box

• Click on "Windows Security" and select "Firewall & Network Protection."

• Turn off your Firewall temporarily by selecting “Turn Off” under “Firewall”.

Once done, attempt connecting again and see if it was indeed the firewall causing the ssh_exchange_identification read Connection reset by peer error!

Advanced Fixes for Persistent Errors

Troubleshooting with verbose mode enabled in SSH client

If the basic troubleshooting steps in section III do not resolve the issue, it may be necessary to use more advanced techniques to diagnose and fix the problem. One such technique is to enable verbose mode on the SSH client. Verbose mode provides detailed information about the SSH connection process, which can help pinpoint where and why the error is occurring.

To enable verbose mode, add the -v option when connecting to the remote server via SSH. For example −

ssh -v username@remote_host.com 

This will cause the SSH client to display a detailed log of its actions during connection establishment. The log may contain error messages that provide clues about what is causing the ssh_exchange_identification read Connection reset by peer error.

Once you have identified a possible cause, you can try adjusting settings or parameters accordingly. If you are unable to identify a specific cause, move on to modifying server-side settings.

Modifying server-side settings to fix persistent errors

If verbose mode does not provide enough information or if you are unable to resolve persistent errors through other means, it may be necessary to modify server-side settings. One common strategy is disabling reverse DNS lookups on the remote server.

Reverse DNS lookups occur when an SSH connection attempts to verify host identities by looking up IP addresses associated with domain names. However, if this process fails or takes too long due to network latency or other factors, it can lead to ssh_exchange_identification read Connection reset by peer errors.

To disable reverse DNS lookups in OpenSSH servers (the most common type), add “UseDNS no” line in /etc/ssh/sshd_config file and restart sshd service. Another strategy involves increasing various timeout values on either end of an SSH connection – for example, adjusting the server's TCP keepalive settings or modifying the client's ConnectionTimeout parameter.

Conclusion

In this article, we have discussed the ssh_exchange_identification read Connection reset by peer error, which is a common issue faced during SSH connections. We have explored the causes and troubleshooting steps to fix this error. The causes can range from network issues to incorrect SSH configuration settings.