Скачать или смотреть How to Resolve the Error reading SSH protocol banner with Paramiko in Python

Discover how to solve the `Error reading SSH protocol banner` issue when using Paramiko to connect to a server on port 443. Learn about the difference between WebDAV and SFTP connections and how to navigate these protocols in Python.
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This video is based on the question https://stackoverflow.com/q/65005579/ asked by the user 'keiv.fly' ( https://stackoverflow.com/u/3596337/ ) and on the answer https://stackoverflow.com/a/65008771/ provided by the user 'Martin Prikryl' ( https://stackoverflow.com/u/850848/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Error: Error reading SSH protocol banner

When developing with Python, specifically using the Paramiko library to handle SSH and SFTP connections, you might encounter an error that can halt your progress: the dreaded Error reading SSH protocol banner. This issue commonly arises when attempting to connect to a server using an unexpected protocol or port.

In this guide, we'll explore the context of this error, the reasons it may arise, and potential solutions to successfully establish the connection you need.

The Problem

In this particular case, a user encountered the following situation:

They successfully connected to a server using WinSCP and the Linux sftp command, indicating that the server supports SFTP.

However, they were met with an error in Paramiko when trying to connect to the server on port 443:

[[See Video to Reveal this Text or Code Snippet]]

Attempts to increase the banner timeout did not resolve the issue, since the error occurred immediately, indicating a fundamental problem in the connection process.

Analyzing the Connection

From the details shared, we see the user employed the following basic structure for connecting with Paramiko:

[[See Video to Reveal this Text or Code Snippet]]

The debug output pointed towards a failure in reading the server's SSH protocol banner.

What’s at Play Here?

As the debugging traces suggest, the connection was made on port 443, commonly designated for HTTPS traffic. What this implies is that your server configuration may not correctly handle SSH/SFTP requests on this port, especially if it primarily serves WebDAV (which is designed for document management over HTTP).

Solution Steps

1. Understanding the Protocols

SFTP (SSH File Transfer Protocol): Securely serves file transfer capabilities through ports like 22.

WebDAV (Web Distributed Authoring and Versioning): Allows clients to create, change, and move documents on a server, typically through HTTP/HTTPS (e.g., port 443).

2. Connect Using the Correct Port

If your server indeed supports SFTP, you should attempt to connect through the standard port 22:

[[See Video to Reveal this Text or Code Snippet]]

3. Verifying Server Capabilities

If using WinSCP works but encounters issues via Paramiko, ensure that the server can handle requests on both SFTP (port 22) and WebDAV (port 443).

4. Utilizing the Right Library

If you're certain your server only supports WebDAV:

Utilize a library that specifically supports WebDAV in Python, such as easywebdav, instead of Paramiko.

By switching to the appropriate library or port based on verified server capabilities, you can avoid the Error reading SSH protocol banner in future connection attempts.

Conclusion

Encountering the Error reading SSH protocol banner while attempting to use Paramiko for server connections can be frustrating, but understanding the difference between the protocols you are dealing with can help clarify potential solutions. By ensuring you use the correct port and library corresponding to your server's capabilities, you can achieve a successful connection efficiently.

Happy coding, and may your connections be seamless!