Package org.apache.commons.net.ftp

# Class FTPSClient

java.lang.Object
org.apache.commons.net.SocketClient
org.apache.commons.net.ftp.FTP
org.apache.commons.net.ftp.FTPClient
org.apache.commons.net.ftp.FTPSClient

All Implemented Interfaces:
  `Configurable`

public class FTPSClient extends FTPClient
FTP over SSL processing. If desired, the JVM property -Djavax.net.debug=all can be used to see wire-level SSL details. Warning: the hostname is not verified against the certificate by default, use `setHostnameVerifier(HostnameVerifier)` or `setEndpointCheckingEnabled(boolean)` (on Java 1.7+) to enable verification. Verification is only performed on client mode connections.

Since:
  2.0

- ## Nested Class Summary

  ## Nested classes/interfaces inherited from class org.apache.commons.net.ftp.FTPClient

  `FTPClient.HostnameResolver, FTPClient.NatServerResolverImpl`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final int`
  `DEFAULT_FTPS_DATA_PORT`
  Default FTPS data port.
  `static final int`
  `DEFAULT_FTPS_PORT`
  Default FTPS port.
  `static String`
  `KEYSTORE_ALGORITHM`
  Deprecated.
  - not used - may be removed in a future release
  `static String`
  `PROVIDER`
  Deprecated.
  - not used - may be removed in a future release
  `static String`
  `STORE_TYPE`
  Deprecated.
  - not used - may be removed in a future release
  `static String`
  `TRUSTSTORE_ALGORITHM`
  Deprecated.
  - not used - may be removed in a future release

  ### Fields inherited from class org.apache.commons.net.ftp.FTPClient

  `ACTIVE_LOCAL_DATA_CONNECTION_MODE, ACTIVE_REMOTE_DATA_CONNECTION_MODE, FTP_IP_ADDRESS_FROM_PASV_RESPONSE, FTP_SYSTEM_TYPE, FTP_SYSTEM_TYPE_DEFAULT, PASSIVE_LOCAL_DATA_CONNECTION_MODE, PASSIVE_REMOTE_DATA_CONNECTION_MODE, SYSTEM_TYPE_PROPERTIES`

  ### Fields inherited from class org.apache.commons.net.ftp.FTP

  `_commandSupport_, _controlEncoding, _controlInput_, _controlOutput_, _newReplyString, _replyCode, _replyLines, _replyString, ASCII_FILE_TYPE, BINARY_FILE_TYPE, BLOCK_TRANSFER_MODE, CARRIAGE_CONTROL_TEXT_FORMAT, COMPRESSED_TRANSFER_MODE, DEFAULT_CONTROL_ENCODING, DEFAULT_DATA_PORT, DEFAULT_PORT, EBCDIC_FILE_TYPE, FILE_STRUCTURE, LOCAL_FILE_TYPE, NON_PRINT_TEXT_FORMAT, PAGE_STRUCTURE, RECORD_STRUCTURE, REPLY_CODE_LEN, STREAM_TRANSFER_MODE, strictMultilineParsing, TELNET_TEXT_FORMAT`

  ### Fields inherited from class org.apache.commons.net.SocketClient

  `_defaultPort_, _hostname_, _input_, _output_, _serverSocketFactory_, _socket_, _socketFactory_, _timeout_, connectTimeout, NETASCII_EOL, remoteInetSocketAddress`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `FTPSClient()`
  Constructor for FTPSClient, calls `FTPSClient(String, boolean)`.
  `FTPSClient(boolean isImplicit)`
  Constructor for FTPSClient, using `DEFAULT_PROTOCOL` - i.e.
  `FTPSClient(boolean isImplicit, SSLContext context)`
  Constructor for FTPSClient, using `DEFAULT_PROTOCOL` - i.e.
  `FTPSClient(String protocol)`
  Constructor for FTPSClient, using explicit mode, calls `FTPSClient(String, boolean)`.
  `FTPSClient(String protocol, boolean isImplicit)`
  Constructor for FTPSClient allowing specification of protocol and security mode.
  `FTPSClient(SSLContext context)`
  Constructor for FTPSClient, using `DEFAULT_PROTOCOL` - i.e.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected void`
  `_connectAction_()`
  Because there are so many connect() methods, the _connectAction_() method is provided as a means of performing some action immediately after establishing a connection, rather than reimplementing all the connect() methods.
  `protected Socket`
  `_openDataConnection_(int command, String arg)`
  Deprecated.
  (3.3) Use `FTPClient._openDataConnection_(FTPCmd, String)` instead
  `protected Socket`
  `_openDataConnection_(String command, String arg)`
  Returns a socket of the data connection.
  `protected void`
  `_prepareDataSocket_(Socket socket)`
  Performs any custom initialization for a newly created SSLSocket (before the SSL handshake happens).
  `void`
  `disconnect()`
  Closes the connection to the FTP server and restores connection parameters to the default values.
  `int`
  `execADAT(byte[] data)`
  Send the ADAT command with the specified authentication data.
  `protected void`
  `execAUTH()`
  AUTH command.
  `int`
  `execAUTH(String mechanism)`
  Send the AUTH command with the specified mechanism.
  `int`
  `execCCC()`
  Send the CCC command to the server.
  `int`
  `execCONF(byte[] data)`
  Send the CONF command with the specified data.
  `int`
  `execENC(byte[] data)`
  Send the ENC command with the specified data.
  `int`
  `execMIC(byte[] data)`
  Send the MIC command with the specified data.
  `void`
  `execPBSZ(long pbsz)`
  PBSZ command.
  `void`
  `execPROT(String prot)`
  PROT command.
  `String`
  `getAuthValue()`
  Return AUTH command use value.
  `String[]`
  `getEnabledCipherSuites()`
  Returns the names of the cipher suites which could be enabled for use on this connection.
  `String[]`
  `getEnabledProtocols()`
  Returns the names of the protocol versions which are currently enabled for use on this connection.
  `boolean`
  `getEnableSessionCreation()`
  Returns true if new SSL sessions may be established by this socket.
  `HostnameVerifier`
  `getHostnameVerifier()`
  Get the currently configured `HostnameVerifier`.
  `boolean`
  `getNeedClientAuth()`
  Returns true if the socket will require client authentication.
  `TrustManager`
  `getTrustManager()`
  Get the currently configured `TrustManager`.
  `boolean`
  `getUseClientMode()`
  Returns true if the socket is set to use client mode in its first handshake.
  `boolean`
  `getWantClientAuth()`
  Returns true if the socket will request client authentication.
  `boolean`
  `isEndpointCheckingEnabled()`
  Return whether or not endpoint identification using the HTTPS algorithm on Java 1.7+ is enabled.
  `byte[]`
  `parseADATReply(String reply)`
  Parses the given ADAT response line and base64-decodes the data.
  `long`
  `parsePBSZ(long pbsz)`
  PBSZ command.
  `int`
  `sendCommand(String command, String args)`
  Send an FTP command.
  `void`
  `setAuthValue(String auth)`
  Set AUTH command use value.
  `void`
  `setEnabledCipherSuites(String[] cipherSuites)`
  Controls which particular cipher suites are enabled for use on this connection.
  `void`
  `setEnabledProtocols(String[] protocolVersions)`
  Controls which particular protocol versions are enabled for use on this connection.
  `void`
  `setEnabledSessionCreation(boolean isCreation)`
  Controls whether a new SSL session may be established by this socket.
  `void`
  `setEndpointCheckingEnabled(boolean enable)`
  Automatic endpoint identification checking using the HTTPS algorithm is supported on Java 1.7+.
  `void`
  `setHostnameVerifier(HostnameVerifier newHostnameVerifier)`
  Override the default `HostnameVerifier` to use.
  `void`
  `setKeyManager(KeyManager keyManager)`
  Set a `KeyManager` to use
  `void`
  `setNeedClientAuth(boolean isNeedClientAuth)`
  Configures the socket to require client authentication.
  `void`
  `setTrustManager(TrustManager trustManager)`
  Override the default `TrustManager` to use; if set to `null`, the default TrustManager from the JVM will be used.
  `void`
  `setUseClientMode(boolean isClientMode)`
  Configures the socket to use client (or server) mode in its first handshake.
  `void`
  `setWantClientAuth(boolean isWantClientAuth)`
  Configures the socket to request client authentication, but only if such a request is appropriate to the cipher suite negotiated.
  `protected void`
  `sslNegotiation()`
  SSL/TLS negotiation.

  ### Methods inherited from class org.apache.commons.net.ftp.FTPClient

  `_connectAction_, _openDataConnection_, _parseExtendedPassiveModeReply, _parsePassiveModeReply, _retrieveFile, _retrieveFileStream, _storeFile, _storeFileStream, abort, allocate, allocate, allocate, allocate, appendFile, appendFileStream, changeToParentDirectory, changeWorkingDirectory, completePendingCommand, configure, deleteFile, doCommand, doCommandAsStrings, enterLocalActiveMode, enterLocalPassiveMode, enterRemoteActiveMode, enterRemotePassiveMode, features, featureValue, featureValues, getAutodetectUTF8, getBufferSize, getControlKeepAliveReplyTimeout, getControlKeepAliveReplyTimeoutDuration, getControlKeepAliveTimeout, getControlKeepAliveTimeoutDuration, getCopyStreamListener, getCslDebug, getDataConnectionMode, getDataTimeout, getListArguments, getListHiddenFiles, getModificationTime, getPassiveHost, getPassiveLocalIPAddress, getPassivePort, getReceiveDataSocketBufferSize, getRestartOffset, getSendDataSocketBufferSize, getSize, getStatus, getStatus, getSystemName, getSystemType, hasFeature, hasFeature, hasFeature, initiateListParsing, initiateListParsing, initiateListParsing, initiateMListParsing, initiateMListParsing, isIpAddressFromPasvResponse, isRemoteVerificationEnabled, isUseEPSVwithIPv4, listDirectories, listDirectories, listFiles, listFiles, listFiles, listHelp, listHelp, listNames, listNames, login, login, logout, makeDirectory, mdtmCalendar, mdtmFile, mdtmInstant, mlistDir, mlistDir, mlistDir, mlistFile, printWorkingDirectory, reinitialize, remoteAppend, remoteRetrieve, remoteStore, remoteStoreUnique, remoteStoreUnique, removeDirectory, rename, restart, retrieveFile, retrieveFileStream, sendNoOp, sendSiteCommand, setActiveExternalIPAddress, setActivePortRange, setAutodetectUTF8, setBufferSize, setControlKeepAliveReplyTimeout, setControlKeepAliveReplyTimeout, setControlKeepAliveTimeout, setControlKeepAliveTimeout, setCopyStreamListener, setDataTimeout, setDataTimeout, setFileStructure, setFileTransferMode, setFileType, setFileType, setIpAddressFromPasvResponse, setListHiddenFiles, setModificationTime, setParserFactory, setPassiveLocalIPAddress, setPassiveLocalIPAddress, setPassiveNatWorkaround, setPassiveNatWorkaroundStrategy, setReceieveDataSocketBufferSize, setRemoteVerificationEnabled, setReportActiveExternalIPAddress, setRestartOffset, setSendDataSocketBufferSize, setUseEPSVwithIPv4, storeFile, storeFileStream, storeUniqueFile, storeUniqueFile, storeUniqueFileStream, storeUniqueFileStream, structureMount`

  ### Methods inherited from class org.apache.commons.net.ftp.FTP

  `__getReplyNoReport, __noop, abor, acct, allo, allo, allo, allo, appe, cdup, cwd, dele, eprt, epsv, feat, getCommandSupport, getControlEncoding, getReply, getReplyCode, getReplyString, getReplyStrings, help, help, isStrictMultilineParsing, isStrictReplyParsing, list, list, mdtm, mfmt, mkd, mlsd, mlsd, mlst, mlst, mode, nlst, nlst, noop, pass, pasv, port, pwd, quit, rein, rest, retr, rmd, rnfr, rnto, sendCommand, sendCommand, sendCommand, sendCommand, sendCommand, setControlEncoding, setStrictMultilineParsing, setStrictReplyParsing, site, size, smnt, stat, stat, stor, stou, stou, stru, syst, type, type, user`

  ### Methods inherited from class org.apache.commons.net.SocketClient

  `addProtocolCommandListener, applySocketAttributes, connect, connect, connect, connect, connect, connect, createCommandSupport, fireCommandSent, fireReplyReceived, getCharset, getCharsetName, getConnectTimeout, getDefaultPort, getDefaultTimeout, getKeepAlive, getLocalAddress, getLocalPort, getProxy, getReceiveBufferSize, getRemoteAddress, getRemoteInetSocketAddress, getRemotePort, getSendBufferSize, getServerSocketFactory, getSoLinger, getSoTimeout, getTcpNoDelay, isAvailable, isConnected, removeProtocolCommandListener, setCharset, setConnectTimeout, setDefaultPort, setDefaultTimeout, setKeepAlive, setProxy, setReceiveBufferSize, setSendBufferSize, setServerSocketFactory, setSocketFactory, setSoLinger, setSoTimeout, setTcpNoDelay, verifyRemote`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### DEFAULT_FTPS_DATA_PORT

    public static final int DEFAULT_FTPS_DATA_PORT
    Default FTPS data port.
    See Also:
      - Constant Field Values

  - ### DEFAULT_FTPS_PORT

    public static final int DEFAULT_FTPS_PORT
    Default FTPS port.
    See Also:
      - Constant Field Values

  - ### KEYSTORE_ALGORITHM

    @Deprecated public static String KEYSTORE_ALGORITHM
    Deprecated.
    - not used - may be removed in a future release

  - ### TRUSTSTORE_ALGORITHM

    @Deprecated public static String TRUSTSTORE_ALGORITHM
    Deprecated.
    - not used - may be removed in a future release

  - ### PROVIDER

    @Deprecated public static String PROVIDER
    Deprecated.
    - not used - may be removed in a future release

  - ### STORE_TYPE

    @Deprecated public static String STORE_TYPE
    Deprecated.
    - not used - may be removed in a future release

- ## Constructor Details

  - ### FTPSClient

    public FTPSClient()
    Constructor for FTPSClient, calls `FTPSClient(String, boolean)`. Sets protocol to `DEFAULT_PROTOCOL` - i.e. TLS - and security mode to explicit (isImplicit = false)

  - ### FTPSClient

    public FTPSClient(boolean isImplicit)
    Constructor for FTPSClient, using `DEFAULT_PROTOCOL` - i.e. TLS Calls `FTPSClient(String, boolean)`
    Parameters:
      `isImplicit` - The security mode (Implicit/Explicit).

  - ### FTPSClient

    public FTPSClient(boolean isImplicit, SSLContext context)
    Constructor for FTPSClient, using `DEFAULT_PROTOCOL` - i.e. TLS The default TrustManager is set from `TrustManagerUtils.getValidateServerCertificateTrustManager()`
    Parameters:
      `isImplicit` - The security mode(Implicit/Explicit).
      `context` - A pre-configured SSL Context

  - ### FTPSClient

    public FTPSClient(SSLContext context)
    Constructor for FTPSClient, using `DEFAULT_PROTOCOL` - i.e. TLS and isImplicit `false` Calls `FTPSClient(boolean, SSLContext)`
    Parameters:
      `context` - A pre-configured SSL Context

  - ### FTPSClient

    public FTPSClient(String protocol)
    Constructor for FTPSClient, using explicit mode, calls `FTPSClient(String, boolean)`.
    Parameters:
      `protocol` - the protocol to use

  - ### FTPSClient

    public FTPSClient(String protocol, boolean isImplicit)
    Constructor for FTPSClient allowing specification of protocol and security mode. If isImplicit is true, the port is set to `DEFAULT_FTPS_PORT` i.e. 990. The default TrustManager is set from `TrustManagerUtils.getValidateServerCertificateTrustManager()`
    Parameters:
      `protocol` - the protocol
      `isImplicit` - The security mode(Implicit/Explicit).

- ## Method Details

  - ### _connectAction_

    protected void _connectAction_() throws IOException
    Because there are so many connect() methods, the _connectAction_() method is provided as a means of performing some action immediately after establishing a connection, rather than reimplementing all the connect() methods.
    Overrides:
      `_connectAction_` in class `FTPClient`
    Throws:
      `IOException` - If there is any problem with establishing the connection.
    See Also:
      - `SocketClient._connectAction_()`

  - ### _openDataConnection_

    @Deprecated protected Socket _openDataConnection_(int command, String arg) throws IOException
    Deprecated.
    (3.3) Use `FTPClient._openDataConnection_(FTPCmd, String)` instead
    Returns a socket of the data connection. Wrapped as an `SSLSocket`, which carries out handshake processing.
    Overrides:
      `_openDataConnection_` in class `FTPClient`
    Parameters:
      `command` - The int representation of the FTP command to send.
      `arg` - The arguments to the FTP command. If this parameter is set to null, then the command is sent with no arguments.
    Returns:
      corresponding to the established data connection. Null is returned if an FTP protocol error is reported at any point during the establishment and initialization of the connection.
    Throws:
      `IOException` - If there is any problem with the connection.
    See Also:
      - `FTPClient._openDataConnection_(int, String)`

  - ### _openDataConnection_

    protected Socket _openDataConnection_(String command, String arg) throws IOException
    Returns a socket of the data connection. Wrapped as an `SSLSocket`, which carries out handshake processing.
    Overrides:
      `_openDataConnection_` in class `FTPClient`
    Parameters:
      `command` - The textual representation of the FTP command to send.
      `arg` - The arguments to the FTP command. If this parameter is set to null, then the command is sent with no arguments.
    Returns:
      corresponding to the established data connection. Null is returned if an FTP protocol error is reported at any point during the establishment and initialization of the connection.
    Throws:
      `IOException` - If there is any problem with the connection.
    Since:
      3.2
    See Also:
      - `FTPClient._openDataConnection_(int, String)`

  - ### _prepareDataSocket_

    protected void _prepareDataSocket_(Socket socket) throws IOException
    Performs any custom initialization for a newly created SSLSocket (before the SSL handshake happens). Called by `_openDataConnection_(int, String)` immediately after creating the socket. The default implementation is a no-op
    Parameters:
      `socket` - the socket to set up
    Throws:
      `IOException` - on error
    Since:
      3.1

  - ### disconnect

    public void disconnect() throws IOException
    Closes the connection to the FTP server and restores connection parameters to the default values.

    Calls `setSocketFactory(null)` and `setServerSocketFactory(null)` to reset the factories that may have been changed during the session, e.g. by `execPROT(String)`

    Overrides:
      `disconnect` in class `FTPClient`
    Throws:
      `IOException` - If an error occurs while disconnecting.
    Since:
      3.0

  - ### execADAT

    public int execADAT(byte[] data) throws IOException
    Send the ADAT command with the specified authentication data.
    Parameters:
      `data` - The data to send with the command.
    Returns:
      server reply.
    Throws:
      `IOException` - If an I/O error occurs while sending the command.
    Since:
      3.0

  - ### execAUTH

    protected void execAUTH() throws SSLException, IOException
    AUTH command.
    Throws:
      `SSLException` - If the server reply code equals neither "234" nor "334".
      `IOException` - If an I/O error occurs while either sending the command.

  - ### execAUTH

    public int execAUTH(String mechanism) throws IOException
    Send the AUTH command with the specified mechanism.
    Parameters:
      `mechanism` - The mechanism name to send with the command.
    Returns:
      server reply.
    Throws:
      `IOException` - If an I/O error occurs while sending the command.
    Since:
      3.0

  - ### execCCC

    public int execCCC() throws IOException
    Send the CCC command to the server. The CCC (Clear Command Channel) command causes the underlying `SSLSocket` instance to be assigned to a plain `Socket` instances
    Returns:
      server reply.
    Throws:
      `IOException` - If an I/O error occurs while sending the command.
    Since:
      3.0

  - ### execCONF

    public int execCONF(byte[] data) throws IOException
    Send the CONF command with the specified data.
    Parameters:
      `data` - The data to send with the command.
    Returns:
      server reply.
    Throws:
      `IOException` - If an I/O error occurs while sending the command.
    Since:
      3.0

  - ### execENC

    public int execENC(byte[] data) throws IOException
    Send the ENC command with the specified data.
    Parameters:
      `data` - The data to send with the command.
    Returns:
      server reply.
    Throws:
      `IOException` - If an I/O error occurs while sending the command.
    Since:
      3.0

  - ### execMIC

    public int execMIC(byte[] data) throws IOException
    Send the MIC command with the specified data.
    Parameters:
      `data` - The data to send with the command.
    Returns:
      server reply.
    Throws:
      `IOException` - If an I/O error occurs while sending the command.
    Since:
      3.0

  - ### execPBSZ

    public void execPBSZ(long pbsz) throws SSLException, IOException
    PBSZ command. pbsz value: 0 to (2^32)-1 decimal integer.
    Parameters:
      `pbsz` - Protection Buffer Size.
    Throws:
      `SSLException` - If the server reply code does not equal "200".
      `IOException` - If an I/O error occurs while sending the command.
    See Also:
      - `parsePBSZ(long)`

  - ### execPROT

    public void execPROT(String prot) throws SSLException, IOException
    PROT command.
    - C - Clear
    - S - Safe(SSL protocol only)
    - E - Confidential(SSL protocol only)
    - P - Private
    N.B. the method calls `SocketClient.setSocketFactory(javax.net.SocketFactory)` and `SocketClient.setServerSocketFactory(javax.net.ServerSocketFactory)`
    Parameters:
      `prot` - Data Channel Protection Level, if `null`, use `DEFAULT_PROT`.
    Throws:
      `SSLException` - If the server reply code does not equal `200`.
      `IOException` - If an I/O error occurs while sending the command.

  - ### getAuthValue

    public String getAuthValue()
    Return AUTH command use value.
    Returns:
      AUTH command use value.

  - ### getEnabledCipherSuites

    public String[] getEnabledCipherSuites()
    Returns the names of the cipher suites which could be enabled for use on this connection. When the underlying `Socket` is not an `SSLSocket` instance, returns null.
    Returns:
      An array of cipher suite names, or `null`

  - ### getEnabledProtocols

    public String[] getEnabledProtocols()
    Returns the names of the protocol versions which are currently enabled for use on this connection. When the underlying `Socket` is not an `SSLSocket` instance, returns null.
    Returns:
      An array of protocols, or `null`

  - ### getEnableSessionCreation

    public boolean getEnableSessionCreation()
    Returns true if new SSL sessions may be established by this socket. When the underlying `Socket` instance is not SSL-enabled (i.e. an instance of `SSLSocket` with `SSLSocket` `getEnableSessionCreation()`) enabled, this returns False.
    Returns:
      true - Indicates that sessions may be created; this is the default. false - indicates that an existing session must be resumed.

  - ### getHostnameVerifier

    public HostnameVerifier getHostnameVerifier()
    Get the currently configured `HostnameVerifier`. The verifier is only used on client mode connections.
    Returns:
      A HostnameVerifier instance.
    Since:
      3.4

  - ### getNeedClientAuth

    public boolean getNeedClientAuth()
    Returns true if the socket will require client authentication. When the underlying `Socket` is not an `SSLSocket` instance, returns false.
    Returns:
      true - If the server mode socket should request that the client authenticate itself.

  - ### getTrustManager

    public TrustManager getTrustManager()
    Get the currently configured `TrustManager`.
    Returns:
      A TrustManager instance.

  - ### getUseClientMode

    public boolean getUseClientMode()
    Returns true if the socket is set to use client mode in its first handshake. When the underlying `Socket` is not an `SSLSocket` instance, returns false.
    Returns:
      true - If the socket should start its first handshake in "client" mode.

  - ### getWantClientAuth

    public boolean getWantClientAuth()
    Returns true if the socket will request client authentication. When the underlying `Socket` is not an `SSLSocket` instance, returns false.
    Returns:
      true - If the server mode socket should request that the client authenticate itself.

  - ### isEndpointCheckingEnabled

    public boolean isEndpointCheckingEnabled()
    Return whether or not endpoint identification using the HTTPS algorithm on Java 1.7+ is enabled. The default behavior is for this to be disabled. This check is only performed on client mode connections.
    Returns:
      True if enabled, false if not.
    Since:
      3.4

  - ### parseADATReply

    public byte[] parseADATReply(String reply)
    Parses the given ADAT response line and base64-decodes the data.
    Parameters:
      `reply` - The ADAT reply to parse.
    Returns:
      the data in the reply, base64-decoded.
    Since:
      3.0

  - ### parsePBSZ

    public long parsePBSZ(long pbsz) throws SSLException, IOException
    PBSZ command. pbsz value: 0 to (2^32)-1 decimal integer. Issues the command and parses the response to return the negotiated value.
    Parameters:
      `pbsz` - Protection Buffer Size.
    Returns:
      the negotiated value.
    Throws:
      `SSLException` - If the server reply code does not equal "200".
      `IOException` - If an I/O error occurs while sending the command.
    Since:
      3.0
    See Also:
      - `execPBSZ(long)`

  - ### sendCommand

    public int sendCommand(String command, String args) throws IOException
    Send an FTP command. A successful CCC (Clear Command Channel) command causes the underlying `SSLSocket` instance to be assigned to a plain `Socket`
    Overrides:
      `sendCommand` in class `FTP`
    Parameters:
      `command` - The FTP command.
      `args` - The arguments to the FTP command. If this parameter is set to null, then the command is sent with no argument.
    Returns:
      server reply.
    Throws:
      `IOException` - If an I/O error occurs while sending the command.
      `SSLException` - if a CCC command fails
    See Also:
      - `FTP.sendCommand(String)`

  - ### setAuthValue

    public void setAuthValue(String auth)
    Set AUTH command use value. This processing is done before connected processing.
    Parameters:
      `auth` - AUTH command use value.

  - ### setEnabledCipherSuites

    public void setEnabledCipherSuites(String[] cipherSuites)
    Controls which particular cipher suites are enabled for use on this connection. Called before server negotiation.
    Parameters:
      `cipherSuites` - The cipher suites.

  - ### setEnabledProtocols

    public void setEnabledProtocols(String[] protocolVersions)
    Controls which particular protocol versions are enabled for use on this connection. I perform setting before a server negotiation.
    Parameters:
      `protocolVersions` - The protocol versions.

  - ### setEnabledSessionCreation

    public void setEnabledSessionCreation(boolean isCreation)
    Controls whether a new SSL session may be established by this socket.
    Parameters:
      `isCreation` - The established socket flag.

  - ### setEndpointCheckingEnabled

    public void setEndpointCheckingEnabled(boolean enable)
    Automatic endpoint identification checking using the HTTPS algorithm is supported on Java 1.7+. The default behavior is for this to be disabled. This check is only performed on client mode connections.
    Parameters:
      `enable` - Enable automatic endpoint identification checking using the HTTPS algorithm on Java 1.7+.
    Since:
      3.4

  - ### setHostnameVerifier

    public void setHostnameVerifier(HostnameVerifier newHostnameVerifier)
    Override the default `HostnameVerifier` to use. The verifier is only used on client mode connections.
    Parameters:
      `newHostnameVerifier` - The HostnameVerifier implementation to set or `null` to disable.
    Since:
      3.4

  - ### setKeyManager

    public void setKeyManager(KeyManager keyManager)
    Set a `KeyManager` to use
    Parameters:
      `keyManager` - The KeyManager implementation to set.
    See Also:
      - `KeyManagerUtils`

  - ### setNeedClientAuth

    public void setNeedClientAuth(boolean isNeedClientAuth)
    Configures the socket to require client authentication.
    Parameters:
      `isNeedClientAuth` - The need client auth flag.

  - ### setTrustManager

    public void setTrustManager(TrustManager trustManager)
    Override the default `TrustManager` to use; if set to `null`, the default TrustManager from the JVM will be used.
    Parameters:
      `trustManager` - The TrustManager implementation to set, may be `null`
    See Also:
      - `TrustManagerUtils`

  - ### setUseClientMode

    public void setUseClientMode(boolean isClientMode)
    Configures the socket to use client (or server) mode in its first handshake.
    Parameters:
      `isClientMode` - The use client mode flag.

  - ### setWantClientAuth

    public void setWantClientAuth(boolean isWantClientAuth)
    Configures the socket to request client authentication, but only if such a request is appropriate to the cipher suite negotiated.
    Parameters:
      `isWantClientAuth` - The want client auth flag.

  - ### sslNegotiation

    protected void sslNegotiation() throws IOException
    SSL/TLS negotiation. Acquires an SSL socket of a control connection and carries out handshake processing.
    Throws:
      `IOException` - If server negotiation fails