SftpClient hangs on Connect/ConnectAsync to atmoz/sftp server #1732

Happened on Fedora 42 (did not test on other OSs if matters), when I spin up atmoz/sftp docker image, and try to connect to it.

Connecting via Linux sftp -P <port> <user>:localhost to the same docker works perfectly fine.

In the atmoz/sftp logs, I see that the client actually authenticates:

[/entrypoint] Executing sshd
Server listening on 0.0.0.0 port 22.
Server listening on :: port 22.
Accepted password for testuser from 172.17.0.1 port 50554 ssh2

However, it will not release Connect/ConnectAsync afterwards.

Configuring timeout in ConnectionInfo or for CancelationTokenSource, has not effect.

Using same SftpClient to connect to another locally spined SFTP, but using SFTP Go server, works fine.

Tried this with multiple SSH.NET versions, from latest back to mid 2024, same behavior.