Therefore, Rebex SFTP client rejects this mismatched signature, which is correct behavior. This cipher is supposed to use SHA-256 hash algorithm for its RSA signature (see RFC 8332), but the signature received from Strato's server is actually a signature based on SHA-1. There is something wrong with Strato server’s implementations of rsa-sha2-256 host key cipher. SshException.ProtocolMessage is 'KeyExchangeFailed'īut this leaves me with a bad gut feeling as it seems to rely on internal implementation details which might change with new Rebex releases.Īny suggestions on this would be appreciated!.SshException.Status is SshExceptionStatus.OperationFailure.SftpException.Code is SftpErrorCode.UnknownError.

If it matches the criteria below, try again with preferred = DSS.

Try to connect with the default (preferred = RSA).

When trying to connect to a popular German cloud storage provider via SFTP (STRATO HiDrive), an SSH key exchange failure exception occurs.Ĭhanging the PreferredHostKeyAlgorithm from RSA (which seems to be the new default since 2019 R1) 'back' to DSS helps and the connection attempt succeeds, but I don't want to hard code it into my application and I want to avoid making this configurable.

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