I’m trying to SSH to a network device but currently failing the authentication. I’m able to connect via the command ssh -i /home/usr/private_key [email protected] but am having no luck with trying to emulate that with Mina SSH. I’m quite confident the username, host, and keypair are correct.
Error:

com.cisco.stbarth.netconf.anc.NetconfException$ProtocolException: org.apache.sshd.common.SshException: No more authentication methods available
        at com.cisco.stbarth.netconf.anc.NetconfSSHClient.createSession(NetconfSSHClient.java:164)
        at com.cisco.stbarth.netconf.anc.EditConfigApplication.main(EditConfigApplication.java:40)
Caused by: org.apache.sshd.common.SshException: No more authentication methods available
        at org.apache.sshd.common.future.AbstractSshFuture.verifyResult(AbstractSshFuture.java:141)
        at org.apache.sshd.client.future.DefaultAuthFuture.verify(DefaultAuthFuture.java:56)
        at org.apache.sshd.client.future.DefaultAuthFuture.verify(DefaultAuthFuture.java:35)
        at org.apache.sshd.common.future.VerifiableFuture.verify(VerifiableFuture.java:121)
        at com.cisco.stbarth.netconf.anc.NetconfSSHClient.createSession(NetconfSSHClient.java:145)
        ... 1 more
Caused by: org.apache.sshd.common.SshException: No more authentication methods available
        at org.apache.sshd.client.session.ClientUserAuthService.tryNext(ClientUserAuthService.java:390)
        at org.apache.sshd.client.session.ClientUserAuthService.processUserAuth(ClientUserAuthService.java:331)
        at org.apache.sshd.client.session.ClientUserAuthService.process(ClientUserAuthService.java:267)
        at org.apache.sshd.common.session.helpers.CurrentService.process(CurrentService.java:109)
        at org.apache.sshd.common.session.helpers.AbstractSession.doHandleMessage(AbstractSession.java:625)
        at org.apache.sshd.common.session.helpers.AbstractSession.lambda$handleMessage$0(AbstractSession.java:546)
        at org.apache.sshd.common.util.threads.ThreadUtils.runAsInternal(ThreadUtils.java:68)
        at org.apache.sshd.common.session.helpers.AbstractSession.handleMessage(AbstractSession.java:545)
        at org.apache.sshd.common.session.helpers.AbstractSession.decode(AbstractSession.java:1718)
        at org.apache.sshd.common.session.helpers.AbstractSession.messageReceived(AbstractSession.java:506)
        at org.apache.sshd.common.session.helpers.AbstractSessionIoHandler.messageReceived(AbstractSessionIoHandler.java:64)
        at org.apache.sshd.common.io.nio2.Nio2Session.handleReadCycleCompletion(Nio2Session.java:409)
        at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:382)
        at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:377)
        at org.apache.sshd.common.io.nio2.Nio2CompletionHandler.lambda$completed$0(Nio2CompletionHandler.java:38)
...

Snippet from NetconfSSHClient.java:

public synchronized NetconfSession createSession() throws NetconfException.ProtocolException {
        ClientSession session;
        try {
            ConnectFuture connect = client.connect(this.username, this.hostname, this.port);
            connect.verify(timeout);
            session = connect.getSession();
        } catch (IOException e) {
            throw new NetconfException.ProtocolException(e);
        }

        if (keypair != null)
            session.addPublicKeyIdentity(keypair);

        try {
**            AuthFuture auth = session.auth().verify(timeout); // line that is erroring **
            if (!auth.isSuccess())
                throw auth.getException();

            ChannelSubsystem channel = session.createSubsystemChannel("netconf");
            OpenFuture open = channel.open().verify(timeout);
            if (!open.isOpened())
                throw open.getException();

            NetconfSession netconfSession = new NetconfSession(
                    this, channel.getInvertedOut(), channel.getInvertedIn(), session::close);
            netconfSession.hello();
            return netconfSession;
        } catch (Throwable e) {
            try {
                session.close();
            } catch (IOException f) {}

            throw (e instanceof NetconfException.ProtocolException) ?
                (NetconfException.ProtocolException)e : new NetconfException.ProtocolException(e);
        }
    }

Snippet from EditConfigApplication.java:

public class EditConfigApplication {

    private static final String HOSTNAME = "12.345.678.90";
    private static final int PORT = 830;
    private static final String USERNAME = "username";
    private static final String KEY_PATH = "anx/.ssh/private_key";
    private static final String FILE_PATH = "anx/edit-config.xml";

    public static void main(String[] args) {
        NetconfSSHClient client = null;
        NetconfSession session = null;

        try {
            client = new NetconfSSHClient(HOSTNAME, PORT, USERNAME);
            KeyPair keyPair = loadKeyPair(KEY_PATH);
            client.setKeyPair(keyPair);
            client.setStrictHostKeyChecking(false);
            client.setTimeout(3600000);
            client.setKeepalive(15000);

            session = client.createSession();

            XMLElement configXML = createEditRequest(FILE_PATH);

            session.editConfig(Netconf.Datastore.CANDIDATE, configXML);

            System.out.println("Edited configuration successfully.");

            session.commit();

            System.out.println("Committed successfully.");

        } catch (NetconfException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
            System.err.println("Failed to read the configuration file.");
        } finally {
            try {
                if (session != null) {
                    session.close();
                }
                if (client != null) {
                    client.close();
                }
            } catch (NetconfException.ProtocolException e) {
                e.printStackTrace();
            }
        }
    }
    private static KeyPair loadKeyPair(String privateKeyPath) throws IOException {
        String privateKeyContent = new String(Files.readAllBytes(Paths.get(privateKeyPath)), StandardCharsets.UTF_8);
        privateKeyContent = privateKeyContent.replaceAll("-----BEGIN (.*)-----", "")
                                             .replaceAll("-----END (.*)-----", "")
                                             .replaceAll("\s", "");

        byte[] keyBytes = Base64.getDecoder().decode(privateKeyContent);

        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory kf;
        PrivateKey privateKey;
        PublicKey publicKey = null;
        try {
            kf = KeyFactory.getInstance("RSA");
            privateKey = kf.generatePrivate(spec);

            // Extract the modulus and public exponent from the private key
            RSAPrivateCrtKeySpec privKeySpec = kf.getKeySpec(privateKey, RSAPrivateCrtKeySpec.class);
            RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(privKeySpec.getModulus(), privKeySpec.getPublicExponent());
            publicKey = kf.generatePublic(pubKeySpec);

        } catch (Exception e) {
            throw new RuntimeException(e);
        }

        return new KeyPair(publicKey, privateKey);
    }
...
}

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.cisco.stbarth.netconf</groupId>
    <artifactId>anc</artifactId>
    <version>0.4-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.apache.sshd</groupId>
            <artifactId>sshd-core</artifactId>
            <version>2.13.1</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>3.2.4</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>com.cisco.stbarth.netconf.anc.EditConfigApplication</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>`
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

I have a feeling that this is due to a proxy jump that creates nested SSH sessions. Any input is helpful!