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The connection was closed by the server: FlowSshTransport: no mutually supported host key algorithm. #1635
Description
After upgrading SSH.NET to the latest version (2025.0.0), I am encountering the following error when attempting to connect. How can I resolve this issue?
The connection was closed by the server: FlowSshTransport: no mutually supported host key algorithm. Local list: DSA. Remote list: ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,Ed25519,ECDSA/nistp256,ECDSA/nistp384,ECDSA/nistp521,RSA/sha2-512,RSA/sha2-256,RSA/sha1. (KeyExchangeFailed).
Activity
Rob-Hague commentedon Apr 29, 2025
Hi, the library has dropped support for DSA because it is very old and we can no longer easily test it (#1558)
The resolution is for the server to use a new host key with a modern algorithm (e.g. Ed25519), or to stay on 2024.2.0
ibrahimsen commentedon Apr 29, 2025
I understand, but since we use it to connect to customer SFTP servers, we do not manage them. I cannot force the companies regarding this issue. I would like to benefit from the new version features, but this is an obstacle for me. Is it possible to make this configurable?
Rob-Hague commentedon Apr 29, 2025
I understand the annoyance, I also had one server which only had a DSA host key and I have asked them to upgrade it. But I'm (personally) not interested in bringing it back:
if you are not satisfied with staying on 2024.2.0 then you can clone the repo and revert 60f3cd8, it applies+builds cleanly on 2025.0.0