Troubleshooting Proxmox: Ssh Works, Web Interface Doesn't

Proxmox Virtual Environment (VE) is a server virtualization management platform that allows users to manage virtual machines, containers, and storage. While Proxmox VE provides a web-based graphical user interface (Web GUI) for remote management, some users have encountered issues with accessing the Web GUI and/or Secure Shell (SSH) service. These issues can range from connection refused errors, to being unable to log in with a specific user, or even complete loss of access to the Web GUI and SSH. Common causes for these issues include network misconfiguration, incorrect file permissions, and conflicting configuration files. Troubleshooting steps may include verifying network settings, checking relevant log files, and reviewing configuration files for errors or discrepancies.

Proxmox node was working fine until user tried to create a new Linux Bridge

Proxmox is a hypervisor that uses the Linux network stack, which provides flexibility in setting up the network on Proxmox VE nodes. However, issues may arise when creating a new Linux Bridge, resulting in the inability to access the GUI or SSH.

In such cases, it is essential to troubleshoot the issue by checking the network configuration and ensuring that the correct IP address is being used. It is also recommended to use a VPN to access Proxmox remotely, as exposing it directly to the internet can pose security risks.

• Check the network configuration: Review the /etc/network/interfaces file to ensure it is correctly configured. You can edit the file manually or use the GUI, which offers better protection against errors.
• Verify IP address: Ensure you are using the correct IP address to access Proxmox. Check if the IP address has changed, and update your records accordingly.
• Use a VPN: For remote access, set up a VPN connection to your Proxmox server. This enhances security and protects your network.
• Check SSH configuration: Examine the /etc/ssh/sshd_config file to ensure it is correctly set up.
• Use SSH port forwarding: Try using SSH port forwarding to access the web UI.
• Disable security tools temporarily: If you are using security tools like fail2ban or ufw, try disabling them temporarily to see if they are causing any issues.
• Check system resources: Monitor the system's RAM usage and swap utilization, especially if using ZFS with limited RAM.

By following these steps, you should be able to troubleshoot and resolve the issue of not being able to access the Proxmox node after creating a new Linux Bridge. Remember to prioritize security when accessing your Proxmox server remotely by using a VPN and avoiding direct exposure to the internet.

User can SSH into containers but not Proxmox

If a user can SSH into containers but not Proxmox, it could be due to a few reasons. One possible cause is a misconfiguration in the network settings, which can result in the Proxmox node not having network access. This can happen if the user created a new Linux Bridge or made changes to the network configuration. To resolve this, the user can access the Proxmox node in rescue mode and check the network configuration file, usually located at /etc/network/interfaces. They may need to mount their root filesystem in the rescue environment to make changes to this file.

Another potential issue could be related to hostname changes. If the user has recently changed their hostname, it's important to update both the /etc/hostname and /etc/hosts files to ensure they have the correct hostname. Mismatched hostnames can cause issues with various services, including Proxmox.

In some cases, the problem may lie with the SSH configuration on the Proxmox host. The user should check the sshd_config file, located at /etc/ssh/sshd_config, and ensure that the correct options are enabled, such as PermitRootLogin and PasswordAuthentication. Additionally, firewall settings or IP address changes could also be factors in the user's inability to SSH into Proxmox.

It's worth noting that directly SSH-ing into a Proxmox LXC container is not possible by default. To enable this, the user can either attach to the container through the Proxmox host using the "lxc-attach" command or allow login with a password on the specific container by modifying the sshd_config file inside the container.

User can't access Proxmox through the web GUI or SSH

If you are unable to access Proxmox through the web GUI or SSH, there could be a few reasons for this. Here are some potential solutions:

• Check your network configuration: Ensure that your network is configured correctly. You can try accessing the Proxmox web GUI by going to https://IP_ADDRESS:8006/. If this doesn't work, try checking your router's gateway and the IP address of the machine you are using to access Proxmox.
• Verify your hostname: Check if you have changed your hostname recently. The issue could be due to a mismatch between the hostname in your shell and the one in the /etc/hosts file. Follow the steps in the Proxmox documentation to rename your PVE node and check all the relevant places where the hostname is mentioned.
• Check your root filesystem: If you are unable to mount your root filesystem, try running the following commands in the rescue mode: vgs -a, vgchange -ay, lvs, mkdir /mnt/pve-root, and mount /dev/mapper/pve-root /mnt/pve-root. Then, edit the network configuration file in the mounted filesystem and reboot your system.
• Check your services: Ensure that all the necessary services are running. You can use the command systemctl status servicename to check the status of a particular service. For example, to check the status of the pveproxy service, use systemctl status pveproxy.service.
• Check your disk space: Use the command df -h to check the available space on your root disk. If you are running out of space, consider freeing up some space or adding more storage.
• Check your Proxmox version: Make sure you are using the latest version of Proxmox. Outdated browsers can also cause issues, so ensure that you are using an up-to-date browser.
• Check your firewall and port settings: Ensure that the necessary ports are open in your router's firewall settings. If you are using a VPN, make sure it is configured correctly.
• Check your logs: Review the logs on your Proxmox system to see if there are any error messages or indications of a security breach.
• Seek further assistance: If none of the above solutions work, consider posting your specific issue on the Proxmox support forum or seeking help from a Proxmox expert. Provide as much detail as possible about your setup and the steps you have already taken to troubleshoot the issue.

User can SSH as root but not with a different username

If a user can SSH as root but not with a different username, it could be due to several reasons. Here are some potential causes and solutions:

• Incorrect username or password: Verify that the username and password are correct for the specific user account. Ensure that the user account has the necessary permissions and access rights to SSH into the system.
• SSH key authentication issues: Check if the SSH keys are set up correctly for the user. Generate new SSH keys or use an SSH key pair if the existing keys are not working.
• Network configuration: Ensure that the network configuration is correct and allows SSH access for the specific user. Check firewall rules, port forwarding settings, and IP address configurations.
• Service status: Verify that the SSH service is running on the Proxmox node. If it is not active, restart the service or enable it using systemctl.
• Host key verification: The client may be rejecting the host key, causing the connection to be refused. Try adding the host key to the known hosts file or using the "-o StrictHostKeyChecking=no" option when connecting.
• Container-specific issues: If the issue occurs only with specific containers, there may be a problem with the container configuration or the Proxmox LXC integration. Check the container settings, network configuration, and permissions for the user within the container.
• Browser-related issues: If using the Proxmox NoVNC browser window, ensure that your browser is up to date and compatible with Proxmox. Try using a different browser or an SSH client for connection.
• Hardware and installation issues: If none of the above solutions work, there may be an issue with the Proxmox installation or the underlying hardware. Consider posting on the Proxmox forums or seeking further technical support to identify any potential problems with your setup.

User can't SSH into Proxmox and gets a connection refused error

If you are unable to SSH into your Proxmox server and are getting a connection refused error, there could be several reasons for this.

First, check if the SSH service is running and if port 22 is open. You can do this by accessing the Proxmox Web Console and checking the firewalls. If the firewalls are empty, it could indicate a problem with the firewall configuration.

Another potential issue could be related to the network configuration. Verify that the network settings on both your client and server are correct and consistent, including the same gateway, DNS, and subnet mask. Additionally, ensure that you are able to ping the server IP from your client machine.

If the issue persists, try restarting the SSHD service with the command "systemctl restart sshd". Also, check the sshd_config file to ensure that root login is allowed if you are trying to SSH as root.

If you are still encountering the connection refused error, try disabling any client and server firewalls temporarily to see if that resolves the issue.

If none of these solutions work, you may need to investigate further by checking log files, verifying disk space, or seeking additional support from the Proxmox community or a Proxmox Commercial Support Subscription.

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