Fixing 'Server Refused Our Key PuTTY' Errors: A Simple Troubleshooting Guide
Getting a "server refused our key PuTTY" message can feel a bit like hitting a brick wall when you're trying to get work done. You're just trying to connect to your server, perhaps to manage some files or run some commands, and then this message pops up. It's a common hiccup, honestly, and it can stop you right in your tracks, making you wonder what went wrong. This guide is here to help you sort it out, giving you clear steps to get back online. We'll look at why this happens and what you can do about it, so you can connect successfully.
When your computer, which we often call a client, tries to talk to a server, it's a bit like trying to open a locked door. The server holds all the important things, like resources, information, and services, for other devices over a network, you know? It's a special computer that provides what other devices ask for, like a helpful assistant, more or less. Just like "My text" explains, a server is a device or software that processes requests and sends replies. So, when your key is refused, it means the server isn't letting you through that door, even though you think you have the right key.
This issue, "server refused our key PuTTY," usually points to a problem with how you're trying to prove who you are to the server. You're using a special key, a bit like a digital ID, to tell the server it's really you. But for some reason, the server isn't accepting that ID. We'll explore the most common reasons this happens and walk through some straightforward fixes, so you can get your connection working today, as a matter of fact.
Table of Contents
- What is a Server and Why Do We Use Keys?
- Common Reasons Your Key Might Be Refused
- Step-by-Step Troubleshooting for PuTTY
- Frequently Asked Questions
- Getting Back to Work
What is a Server and Why Do We Use Keys?
How Servers Work
A server, as "My text" points out, is a hardware device or software that takes requests sent over a network and replies to them. Think of it as a central hub, you know, for information and services. It provides resources, information, and services to other computers, which we call clients, over a network. A client, in contrast, is the device that sends a request and waits for a response. So, your computer using PuTTY is the client here, asking the server for access, actually.
In the past, each server, like a web server or a database server, would often sit on its own physical machine, more or less. However, as "My text" also mentions, this idea is now changing with virtualization. This means one physical server can act like many separate servers, which is pretty neat. The server's operating system, like Windows Server 2022 or Linux Mint 22, acts as the base that allows different applications to run. It gives these applications access to the server's hardware, basically.
The Role of SSH Keys
When you connect to a server using PuTTY, you're often using something called SSH, which stands for Secure Shell. This is a secure way to access a server, keeping your information private. Instead of just a password, many people use SSH keys for a more secure connection, you know. An SSH key pair has two parts: a public key and a private key. The public key lives on the server, while the private key stays on your computer. When you try to connect, the server challenges your private key, and if they match, you're let in. This system is very secure, so.
The "server refused our key PuTTY" message means this key-based authentication process failed. It's like the server looked at your digital ID and said, "Nope, that's not right," or "I don't recognize this." This could be for many reasons, which we'll get into, but it's all about making sure the server trusts who you say you are. This trust is pretty important for keeping your data safe, as a matter of fact.
Common Reasons Your Key Might Be Refused
There are several common reasons why a server might not accept your SSH key when you're using PuTTY. Knowing these can help you pinpoint the problem quickly, you know. It's often a small detail that's out of place, so.
Incorrect Key Selection in PuTTY
One very common mistake is simply picking the wrong private key file in PuTTY. You might have several key files on your computer, and if you choose the one not linked to the public key on the server, the connection will fail, more or less. PuTTY needs the exact private key that goes with the public key stored on the server you're trying to reach, you see.
Wrong Username
Even with the correct key, if you're trying to connect with a username the server doesn't expect for that key, it won't work. Each public key on the server is usually tied to a specific user account. So, if you try to log in as "admin" but your key is set up for "ubuntu," you'll get that refusal message, you know. This is a pretty easy thing to overlook, actually.
File Permissions on the Server
This is a big one, honestly. On Linux servers, the permissions on your SSH key files and directories are very strict. If they're too open, meaning other users could read or write to them, the SSH server will simply ignore your key for security reasons. The `~/.ssh` directory and the `~/.ssh/authorized_keys` file (where your public key lives) need very specific, restricted permissions. This is a common security practice, so.
Public Key Not on the Server
This might sound obvious, but sometimes the public key just isn't there on the server at all. Maybe you forgot to upload it, or it got deleted, or perhaps you're trying to connect to a new server where you haven't set up key-based authentication yet. Without the public key in the `authorized_keys` file on the server, there's no way for the server to verify your private key, you know. It's like trying to use a house key on a house that doesn't have a matching lock, basically.
Key Format Issues
PuTTY uses its own special format for private keys, which is usually a `.ppk` file. If you generated your key using another tool, like `ssh-keygen` on a Linux system, it will be in a different format. You need to convert these keys to the PuTTY format using PuTTYgen before PuTTY can use them. Trying to use a non-`.ppk` key directly in PuTTY will lead to issues, as a matter of fact.
SSH Agent Problems (Pageant)
PuTTY comes with a tool called Pageant, which is an SSH agent. It holds your private keys in memory so you don't have to enter your passphrase every time you connect. If Pageant isn't running, or if your key isn't loaded into it, PuTTY might not be able to find your key, even if it's the right one. This can definitely cause a "server refused our key" message, you know. It's a handy tool when it works right, but can cause confusion when it doesn't, so.
Server-Side Configuration Troubles
The server's SSH configuration file, often found at `/etc/ssh/sshd_config`, controls how the server accepts connections. If this file has settings that disallow key-based authentication, or if it's looking for keys in a different place, your connection will be refused. Sometimes, after making changes to this file, the SSH service needs to be restarted for them to take effect, you see. This is a less common issue for personal setups but can happen in managed environments, pretty much.
Firewall Blocking
While less directly related to "key refused," a firewall, either on your local computer or on the server, could be preventing the SSH connection from even starting properly. If the connection can't even get to the point where the key is checked, it might manifest as a refusal, though usually, it's a "connection timed out" message. Still, it's worth checking if other issues persist, you know. Sometimes, these things are a bit interconnected, in a way.
Step-by-Step Troubleshooting for PuTTY
Let's walk through some practical steps to figure out why your server is refusing your key. We'll start with the simplest things and move to more involved checks, so.
Check Your PuTTY Settings
First, open PuTTY and load your saved session, or enter the server's IP address or hostname. Go to "Connection" > "SSH" > "Auth" in the left-hand menu. Make sure the "Private key file for authentication" box points to the correct `.ppk` file on your computer. Double-check the path, you know, and confirm it's the right key for that specific server. It's easy to pick the wrong one, honestly.
Also, verify that the "Allow agent forwarding" box is checked if you're using Pageant. If you're using a passphrase for your key, you'll need to enter it when prompted, unless Pageant is handling it. Sometimes, people just forget to actually load the key into PuTTY's settings, which is a pretty simple fix, in a way.
Verify Your Username
Before you try to connect, go to "Connection" > "Data" in the PuTTY configuration window. Look for the "Auto-login username" field. Make sure the username entered here is the correct one for the public key on the server. Common default usernames include `root`, `ubuntu`, `ec2-user`, or `centos`, depending on your server's operating system or cloud provider. A mismatch here will definitely cause a refusal, you know.
If you're unsure, try connecting with a common username first, or consult your server provider's documentation. This step is often overlooked, yet it's a quick thing to check. It's like having the right key but trying to open the neighbor's door, basically.
Inspect Server-Side Files
This step requires you to log into your server using another method, perhaps with a password if it's still enabled, or via a web-based console provided by your hosting company. Once logged in, you need to check the `~/.ssh/authorized_keys` file for the user you're trying to connect as. The `~` symbol means the user's home directory. So, for the user 'john', it would be `/home/john/.ssh/authorized_keys`, you know.
Use commands like `ls -la ~/.ssh` to list the contents and permissions of the `.ssh` directory. Then, use `cat ~/.ssh/authorized_keys` to view the contents of the public key file. Make sure your public key is actually in this file, and that it's on a single line, without any extra spaces or line breaks. Any small error here can cause a problem, as a matter of fact.
Re-Add Your Public Key
If you find your public key is missing or looks incorrect in `authorized_keys`, you'll need to add it again. First, get your public key. If you generated your key with PuTTYgen, open PuTTYgen, load your private key, and copy the public key displayed at the top. On the server, you can use a text editor like `nano` or `vi` to open `~/.ssh/authorized_keys`. Add your public key on a new line. Save the file, you know.
After adding the key, it's absolutely vital to set the correct permissions. Use these commands:
- `chmod 700 ~/.ssh` (This makes the .ssh directory accessible only to the owner)
- `chmod 600 ~/.ssh/authorized_keys` (This makes the authorized_keys file readable and writable only by the owner)
Confirm Key Format
If your private key isn't a `.ppk` file, you'll need to convert it. Open PuTTYgen. Click "Load" and select "All Files (*.*)" to find your non-PuTTY format private key. Once loaded, PuTTYgen will show you the public key and then you can click "Save private key" to save it in the `.ppk` format. Make sure you save it with a `.ppk` extension, you know. Then, use this newly saved `.ppk` file in your PuTTY session settings. This is a pretty common step for keys generated outside of PuTTYgen, as a matter of fact.
Restart Pageant or SSH Agent
If you're using Pageant, close it from your system tray (right-click the icon and choose "Exit"). Then, open it again from your Windows Start menu. Once Pageant is running, right-click its icon in the system tray, select "Add Key," and load your `.ppk` private key. Enter your passphrase if it has one. Make sure your key is actually listed in Pageant's window. Sometimes, a simple restart can fix little glitches, you know.
If you're on a Linux or macOS client and using a different SSH agent, you might try `ssh-add -D` to remove all loaded keys, then `ssh-add /path/to/your/private_key` to add it again. This helps clear out any old or incorrect key entries, basically.
Review Server Logs
If the issue is still there, checking the server's SSH logs can give you very specific clues. Log into the server using another method. The SSH daemon logs are typically found in `/var/log/auth.log` on Debian/Ubuntu systems or `/var/log/secure` on CentOS/RHEL systems. Use a command like `tail -f /var/log/auth.log` (or `secure`) and then try to connect with PuTTY again. The log messages will often tell you exactly why the key was refused, like "bad permissions" or "no matching public key found." This is a very helpful step for digging deeper, you know.
Check Firewall Rules
While often leading to different error messages, it's still good to confirm firewalls aren't getting in the way. On the server, check if the SSH port (usually port 22) is open. Commands like `sudo ufw status` (Ubuntu) or `sudo firewall-cmd --list-all` (CentOS/RHEL) can show you active firewall rules. Ensure port 22 is allowed for incoming connections. On your local computer, make sure your operating system's firewall isn't blocking PuTTY from making outbound connections. This is less likely to cause a "key refused" message but can stop the connection entirely, you know. Sometimes, it's just a simple setting that's off, in a way.
For more general information on how servers work and their different types, you can learn more about servers and their uses. Understanding the basic role of a server can help put these connection issues into a wider context, honestly.
Frequently Asked Questions
Here are some common questions people ask about this "server refused our key PuTTY" problem:
Why
Putty SSH "Server refused our key" Fix - Joscor LLC
Putty SSH "Server refused our key" Fix - Joscor LLC
PuTTY Server Refused Our Key | How to Troubleshoot (Step-by-step Guide)
