Renci.SSH Error in VB.Net, Getting Renci.SshNet.Common.SshConnectionException: An established connection was aborted by the server.

[Jeffs-GitHub]

Attempts to connect to a server using Renci.SSH result in an exception.

The device can be accessed usingTeraterm.

.Net gives this exception:
Renci.SshNet.Common.SshConnectionException: An established connection was aborted by the server.
at Renci.SshNet.Session.WaitOnHandle(WaitHandle waitHandle, TimeSpan timeout)
at Renci.SshNet.Session.WaitOnHandle(WaitHandle waitHandle)
at Renci.SshNet.Session.Connect()
at Renci.SshNet.BaseClient.CreateAndConnectSession()
at Renci.SshNet.BaseClient.Connect()

This is the output from Debug:
SshNet.Logging Verbose: 1 : Initiating connection to '<my_ip_addr>:22'.
SshNet.Logging Verbose: 1 : Server version '2.0' on 'OpenSSH_9.2p1 Debian-2+deb12u3'.
SshNet.Logging Verbose: 5 : [] Received message 'KeyExchangeInitMessage' from server: 'SSH_MSG_KEXINIT'.
SshNet.Logging Verbose: 5 : [] Sending message 'KeyExchangeInitMessage' to server: 'SSH_MSG_KEXINIT'.
SshNet.Logging Verbose: 5 : [] Sending message 'KeyExchangeDhGroupExchangeRequest' to server: 'SSH_MSG_KEX_DH_GEX_REQUEST'.
SshNet.Logging Verbose: 5 : [] Raised exception: Renci.SshNet.Common.SshConnectionException: An established connection was aborted by the server.
SshNet.Logging Verbose: 1 : [] Disposing session.
SshNet.Logging Verbose: 1 : [] Disconnecting session.
SshNet.Logging Verbose: 1 : [] Shutting down socket.
SshNet.Logging Verbose: 1 : [] Disposing socket.
SshNet.Logging Verbose: 1 : [] Disposed socket.
SshNet.Logging Verbose: 5 : [] Disconnecting after exception: Renci.SshNet.Common.SshConnectionException: An established connection was aborted by the server.
at Renci.SshNet.Session.WaitOnHandle(WaitHandle waitHandle, TimeSpan timeout)
at Renci.SshNet.Session.WaitOnHandle(WaitHandle waitHandle)
at Renci.SshNet.Session.Connect()
at Renci.SshNet.BaseClient.CreateAndConnectSession()
Exception thrown: 'Renci.SshNet.Common.SshConnectionException' in Renci.SshNet.dll

Here is some version info:
Renci.SshNet, Version=2020.0.1.0
Microsoft Visual Studio Professional 2022 (64-bit) - Current Version 17.10.1

It looks like my server did not like the key exchange request.

In Teraterm, it says "The server's host key fingerprint is: Fingerprint hash algorithm SHA256" then shows the hash.

Does anyone have any ideas that I could try? Is there any other information I could provide in helping find a solution?

[Rob-Hague]

Hi, do you see the same problem on the latest version 2024.2.0? Or at least 2023.0.1. Quite a lot has changed in the library since 2020.0.1

If the problem still occurs, the next step would probably be to capture a packet trace with wireshark or similar. That might inform a bit more about the exact contents and flow of the initial exchange packets