Что такое фатальная ошибка putty

Discover effective solutions that actually work

by Tashreef Shareef

Tashreef Shareef is a software developer turned tech writer. He discovered his interest in technology after reading a tech magazine accidentally. Now he writes about everything tech from… read more

Updated on May 31, 2023

Reviewed by
Alex Serban

After moving away from the corporate work-style, Alex has found rewards in a lifestyle of constant analysis, team coordination and pestering his colleagues. Holding an MCSA Windows Server… read more

PuTTy is a free and open-source terminal application that allows the system administrator to log in to a remote server over SSH. This small yet highly stable application is also used to transfer files securely via SCP and SFTP.

If you work in IT or have your own set of servers that need to be connected, PuTTy is not an alien concept to you. However, what can be an alien concept is the Putty Fatal error.

The fatal error “Network error: connection refused” in Windows 10 is one of the common PuTTY-related errors that you may face while working with Putty. The error pops up when you try to connect to a remote server for the first time or the 100^th time.

I have had my fair share of problems with PuTTy, but most of the time, the errors are caused by small but not-so-obvious issues.

If you are one of those trying to diagnose a connection refused error, this article will help you to resolve the error.

In this article, I have listed all the possible solutions to the PuTTy connection refused error. Make sure you try each one of them a try until the issue is resolved.

What causes Network error: Connection Refused errors?

The error can occur due to several reasons. Some of them are listed below.

• If the application tries to access the services not offered/supported by the server
• If the application tries to connect to a telnet server not supported by the server.
• Users may encounter a Putty Fatal Network error: connection refused.
• If your router blocks the connection due to security reasons.
• If the server does not support the default port used by the system administrator on PuTTy.

These are some of the common reasons for network error: connection refused error in PuTTy. Below are some common solutions that you can try to fix the issue.

How do I fix a connection refused error in PuTTY?

1. Contact the system/network administrator

If you are not a system administrator, it is a better idea to start by contacting your system administrator.

System Administrators may change some permissions in the router if they notice any unknown device trying to connect or for other security reasons from time to time.

If that’s the case, you can easily resolve the issue by contacting the system admin before trying to resolve the issue on your end. While you are at it, you can also tell him about how NetCrunch Tools could help with their daily tasks.

2. Check if the SSH connection is enabled

Depending on the device you are trying to connect, the network error – connection refused error may appear if the device settings have SSH disabled.

For example, if you are using Raspberry Pi to connect through your PC, make sure SSH is enabled in the configuration. Here is how to do it.

In Raspberry Pi, go to Configuration > Interfaces > ssh. Enable the service and try again.

The settings may change depending on the device you are using, but the end result should be a working network connection through PuTTy.

3. Check if your domain records point to the server

If you are working with a new server and a fresh domain, the error can occur due to an incorrect DNS server address in the domain settings. All the domain registrar allows you to point your domain to you any third-party hosting provider using the name server.

If you have only installed a server and did not change the name server, you might end up with a network error: connection refused error.

To fix the problem, log in to your domain name provider and check the name server settings to see if the name servers are pointing to your hosting provider.

4. Check for Blacklisted and Whitelisted IP Addresses in the server

For security reasons, system administrator may allow connection from only computers with a known IP address that is already whitelisted in the configuration file.

If your ISP IP address has changed or if you are new to the job, you probably need to ask the network admin to make an exception.

The same can also happen if your IP address is blacklisted by the network admin accidentally.

So, check with your network admin for both scenarios and see if that can help you resolve the issue.

5. Disable Firewall

5.1 Disable Firewall in Windows Security

1. Click on Start and select Settings.
2. Open Update and Security, and click on Windows Security.
   
3. Open Firewall and network protection.
   
4. Select the preferred network type (Public, Private or  Domain Network) and disable Windows Defender Firewall.

If you are using Windows, your anti-virus or the default Windows Security firewall and network protection feature may block incoming connections resulting in a connection refused error.

Try disabling the firewall temporarily to see if that can resolve the connection refused error. If it does, you may need to tweak the firewall setting to fix the error completely.

5.2 Disable Anti-virus Firewall

If you have a third-party anti-virus program running, you may also need to disable the firewall offered by the application. You can disable the firewall from the anti-virus settings option.

Try to connect using PuTTy now. If the connection goes through, you need to tweak Firewall settings to fix the problem.

Even so, having a compatible antivirus solution installed on your PC keeps you safe and protected all the time without interfering with your tasks or activities.

Therefore, we strongly recommend choosing the best antivirus for your PC, even though right now, as a temporary workaround, you can disable the Firewall and fix this issue. It is not recommendable to be vulnerable to dangerous attacks throughout the network.

Other Fixes

If none of the fixes worked, you could try to restart the SSH server or reboot the servers.

If your server was set up by someone else, the possibility is that they may have moved the default port as per their convenience. Contact and ask for the configuration nodes to get a better idea of the ports.

If you are using a fully managed server, contact support. If the issue is from the hosting provider’s end, the system administrator will fix the issue.

Last but not the least, start using other alternatives to Putty, such as other SH terminals, in case you encounter an error that is specific to PuTTY.

The Putty Fatal error “Network error: connection refused error can occur due to several reasons, and we have tried to list the most common problems and solutions for the same.

However, if the fixes listed in this article don’t work for you, you may ask in forums related to your device or OS on which the error is appearing.

Do let us know if any of the fixes worked for you or if you have a solution that is not listed in the article in the comments below.

“Hey, I’m unable to connect via PuTTY. How to fix this PuTTY fatal error?”

We often get support requests like this from server/VPS users as part of our white label technical support for Web, VPS, and Datacenter providers.

A PuTTY fatal error occurs when users are unable to access the server.

Today, we’ll go through the top 3 reasons for this error, and how we fix them.

What are the possible causes and fixes of PuTTY fatal error?

We have seen many reasons for connection refused error when connecting via SSH in PuTTY.

Today, we will discuss the top 3 reasons in detail.

• IP not enabled in the firewall
• Delay in DNS propagation
• Blacklisted IP

Read on to know more about these causes and how we fix them.

IP not enabled in the firewall

In Windows PCs, the firewall may block outgoing SSH connections.

To verify this, we ask the customer to disable the Windows firewall and retry connecting.

We recommend these steps for disabling the firewall.

• Click on Start and select Settings.
• Open Update and Security > Windows Security.
• Open Firewall and network protection.
• Select preferred network type and disable Windows Defender Firewall.

If the customer is able to connect successfully, then we ask them to add an SSH rule.

Our customers use the steps for adding the rule:

1. On Start >> Administrative tools >> Windows Firewall with Advanced Security.
2. Then, go to Outbound Rule >> New Rule
3. Click on Custom and on the next page select All Programs.
4. Now, at Protocol & Ports wizard. Select the protocol type to the Any and click next.
5. Next, select any IP address option in “which local IP address does this rule apply to?“.
6. Select these IP addresses option in “which remote IP address does this rule apply to?“.
7. Click on the Add button and enter the IP Address and click OK and Next.
8. Select Allow the connection option and click Next.
9. On the Profile Page, select all three options. Domain, Private, and Public.
10. Click Next Button.
11. In the Last step, We need to provide the Name of this Rule.
12. Click on the Finish button.

This should fix the problem.

Delay in DNS propagation

When you have modified the domain settings like pointing to a new name server or host, there might be some propagation delay.

Propagation delay depends on the TTL value. TTL (Time To Live) value is used to speed up the website load time by caching a copy of DNS records for a period of time, mostly up to 48 hours.

In some cases, after migration, there will be a delay to reflect the change due to a high TTL value. If so, the domain might still be pointing to the old IP causing connection refused error.

If your domain was recently migrated, you may need to check with your hosting provider to see if your DNS has not fully propagated.

At Bobcares to avoid such situations by keeping the TTL value to less than 5 mins.

Blacklisted IP

Most Linux servers will have security software such as Fail2Ban and LFD that detects repeated login failures and blocks the connecting IP. This is done to prevent brute force attacks.

There are cases where even legitimate users of the server are blocked by anti-brute force tools.

It happens when the Email tool, FTP tool, or SSH tool has the wrong login details saved in them, and the tool repeatedly tries to log in to the server resulting in repeated login failures.

So, one among the first things we do to investigate PuTTY errors is to check the firewall log to see if the customer’s IP is blocked, and why.

If so, we reset the login details for them, and remove the IP from the blacklist.

If you feel your IP may be blocked at the server, contact your hosting provider to get it delisted.

[Need assistance in fixing PuTTY Fatal Error? – We’ll help you]

Conclusion

Today we’ve seen how Firewall configuration, DNS propagation, and IP blacklisting can cause PuTTY fatal error, and how our Support Engineers help VPS/Server users fix it as part of our White label technical support services.

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PuTTY is a free and open-source terminal emulator. The software helps us to configure routers, switches, and other networking devices via the command line. It supports many network protocols, including SCP, SSH, Telnet, rlogin, and raw socket connection. However, a lot of users are reporting seeing PuTTy Fatal Error while trying to make the connection between devices. In this article, we will know the causes of this error and see what we can do if our computer says Network Error and the accompanying message could vary as follows:

PuTTy Fatal Error, Network Error

• Software caused connection abort
• Connection timed out
• Connection refused

If you encounter PuTTy Fatal Error, Network error, Software caused connection abort or Connection timed out or was refused on Windows 11/10, then follow the solutions mentioned below to resolve the issue:

1. Check the Internet connection
2. Make sure the port number and protocol are correct.
3. Check if the SSH connection is enabled.
4. Disable Firewall and Anti-virus temporarily
5. Run a CLI Command
6. Contact IT manager

Let’s get started.

1] Check the Internet connection

Sometimes basic tips can be the root cause of the issue and as the error code is related to the Internet connection, we’ll suggest you make sure that the Internet is stable, and cables are connected properly both to the PC and the router. First of all, check the network speed using one of the free Internet speed testers. In case the speed is slow, we should restart the router once, and lastly, if rebooting your router was of no help, then contact your ISP.

2] Make sure the port number and protocol are correct

The error code indicates that the server denied the network connection attempt PuTTY made to it, due to which PuTTy does not have access to the server. This is probably due to incorrect protocol and port number; therefore, it is advisable to make sure the port number and protocol (SSH, Telnet, or Rlogin) we are using are correct while accessing any device. However, one more thing to Keep in mind is that only a system administrator who has full control can resolve the error by restarting stopped telnet and SSH services. So, if we are a part of an organization, contact the administrator and ask them for the correct details.

3] Check if the SSH connection is enabled

It has been seen that even after the user had made sure that the port and protocol were correct, they were still unable to access the device. Usually, this issue occurs due to disabled SSH on the device. If it is already enabled, then we can see the next solutions; however, if it’s disabled, then we can resolve the issue by enabling this protocol on the device, and to do the same, follow the steps prescribed below.

• Press Windows + I key to open the Setting app.
• Click on the Apps option here.
• Click on Optional features.
• Click on View feature next to Add an optional feature.
• Now we can enable SSH from there.

Finally, see if the issue is resolved after enabling the SSH feature on the computer and if the problem continues to persist, see the next solution.

4] Disable Firewall and anti-virus temporarily

We know how important antivirus or Windows Security firewall is for our computers, both utilities can help our computers to work smoothly and safely from malware and viruses. A lot of time, anti-virus or the Windows Security firewall feature blocks some of the incoming connections resulting in the error in question. Now in this scenario, we need to turn off the firewall and anti-virus temporarily and then check if that can resolve the connection refused error.

To turn off the Windows firewall, follow the prescribed steps.

• Press Windows + I key to open the Setting option.
• On the left side of the screen, click on Privacy & security option.
• Now, click on the Windows Security option there and then on Open Windows Security.
• Click on Firewall & network protection option and select Public Network.
• Under the Microsoft Defender Firewall, click on the toggle-off button.

Follow the given steps to disable the anti-virus on the Windows computer.

• Press the Windows key and type Setting in the search bar.
• On the left side of the screen, click on Privacy & security option.
• Now, click on the Windows Security option there and then click on Open Windows Security.
• Click on Virus & threat protection option.
• Click on Manage Setting under Virus & threat protection.
• Under the Real-time protection option, turn off the toggle.

If you use a 3rd-party security software, you will need to disable it too.

Hopefully, after disabling the anti-virus and firewall, the said error issue will be resolved.

5] Run a CLI Command

If there is some misconfiguration in the login process, there is a high chance that we can’t connect to ResberryPie, in that case, we need to execute the following command.

$ sudo rm /etc/ssh/ssh_host_* && sudo dpkg-reconfigure openssh-server

We can try logging in using this command and our issue will be resolved.

6] Contact the IT manager

The error in question can be due to a lack of access permission for the device, in such scenarios, we should contact our organization’s IT manager. We can also contact them if none of the solutions worked or if you don’t want to do all these steps.

Hopefully, you can resolve the issue using the solutions mentioned in this post.

Read: Best PuTTy alternative for SSH Clients for Windows computers.