SSH authentication bug

A sandbox to reproduce an authentication issue when having the SSH server built with https://github.com/mscdex/ssh2 and the SSH client built with https://pkg.go.dev/golang.org/x/crypto/ssh.

Building

Server

Requires Node.js being installed on your system.

$ cd server
$ npm install
$ node index.js

It started successfully if it prints the following message:

SSH server successfully started on ssh://127.0.0.1:8022

Client

Requires Golang being installed on your system.

$ cd client
$ go build
$ ./ssh-client

Issue

When starting the ssh-client while having the provided example server running, it prints the following error message:

2024/03/21 09:07:40 Failed to dial: ssh: handshake failed: ssh: unable to authenticate, attempted methods [none publickey], no supported methods remain

The server prints the following messages for the client authentication request:

SSH Client connected
authentication none test
Auth request with method none
authentication publickey test
User test successfully authenticated with public key
Client disconnected

Even though the server offers and accepts the publickey authentication method, the client fails the handshake.

OpenSSH Client

When using an openssh client, it works:

$ mkdir -p openssh
$ cd openssh
$ ssh-keygen -t rsa -b 2048 -f id_rsa
$ ssh -v -i id_rsa -p 8022 -l test localhost

The OpenSSH client debug logs contain the following lines:

debug1: Offering public key: ...
debug1: Server accepts key: ...
Authenticated to localhost ([127.0.0.1]:8022) using "publickey".

And the server will print the following lines:

SSH Client connected
authentication none test
Auth request with method none
authentication publickey test
User test successfully authenticated with public key
Client authenticated!
Client disconnected