| java.lang.Object
 org.apache.commons.net.SocketClient
org.apache.commons.net.bsd.RExecClient
All known Subclasses: org.apache.commons.net.bsd.RCommandClient,
| RExecClient | | public class RExecClient extends SocketClient (Code) | | RExecClient implements the rexec() facility that first appeared in
4.2BSD Unix. This class will probably only be of use for connecting
to Unix systems and only when the rexecd daemon is configured to run,
which is a rarity these days because of the security risks involved.
However, rexec() can be very useful for performing administrative tasks
on a network behind a firewall.
As with virtually all of the client classes in org.apache.commons.net, this
class derives from SocketClient, inheriting its connection methods.
The way to use RExecClient is to first connect
to the server, call the
RExecClient.rexec rexec() method, and then
fetch the connection's input, output, and optionally error streams.
Interaction with the remote command is controlled entirely through the
I/O streams. Once you have finished processing the streams, you should
invoke
RExecClient.disconnect disconnect() to clean up properly.
By default the standard output and standard error streams of the
remote process are transmitted over the same connection, readable
from the input stream returned by
RExecClient.getInputStream getInputStream() . However, it is
possible to tell the rexecd daemon to return the standard error
stream over a separate connection, readable from the input stream
returned by
RExecClient.getErrorStream getErrorStream() . You
can specify that a separate connection should be created for standard
error by setting the boolean separateErrorStream
parameter of
RExecClient.rexec rexec() to true .
The standard input of the remote process can be written to through
the output stream returned by
RExecClient.getOutputStream getOutputSream() .
author:
Daniel F. Savarese
See Also: SocketClient
See Also: RCommandClient
See Also: RLoginClient |
| Field Summary | |
| final public static int | DEFAULT_PORT
The default rexec port. | | protected InputStream | _errorStream_
If a separate error stream is requested, _errorStream_
will point to an InputStream from which the standard error of the
remote process can be read (after a call to rexec()). |
| Constructor Summary | |
| public | RExecClient()
The default RExecClient constructor. |
| Method Summary | |
| InputStream | _createErrorStream()
| | public void | disconnect()
Disconnects from the server, closing all associated open sockets and
streams. | | public InputStream | getErrorStream()
Returns the InputStream from which the standard error of the remote
process can be read if a separate error stream is requested from
the server. | | public InputStream | getInputStream()
Returns the InputStream from which the standard outputof the remote
process can be read. | | public OutputStream | getOutputStream()
Returns the OutputStream through which the standard input of the remote
process can be written. | | final public boolean | isRemoteVerificationEnabled()
Return whether or not verification of the remote host providing a
separate error stream is enabled. | | public void | rexec(String username, String password, String command, boolean separateErrorStream)
Remotely executes a command through the rexecd daemon on the server
to which the RExecClient is connected. | | public void | rexec(String username, String password, String command)
| | final public void | setRemoteVerificationEnabled(boolean enable)
Enable or disable verification that the remote host connecting to
create a separate error stream is the same as the host to which
the standard out stream is connected. |
| DEFAULT_PORT | | final public static int DEFAULT_PORT(Code) | | The default rexec port. Set to 512 in BSD Unix.
|
| _errorStream_ | | protected InputStream _errorStream_(Code) | | If a separate error stream is requested, _errorStream_
will point to an InputStream from which the standard error of the
remote process can be read (after a call to rexec()). Otherwise,
_errorStream_ will be null.
|
| RExecClient | | public RExecClient()(Code) | | The default RExecClient constructor. Initializes the
default port to DEFAULT_PORT .
|
| disconnect | | public void disconnect() throws IOException(Code) | | Disconnects from the server, closing all associated open sockets and
streams.
exception:
IOException - If there an error occurs while disconnecting. |
| getErrorStream | | public InputStream getErrorStream()(Code) | | Returns the InputStream from which the standard error of the remote
process can be read if a separate error stream is requested from
the server. Otherwise, null will be returned. The error stream
will only be set after a successful rexec() invocation.
The InputStream from which the standard error of the remoteprocess can be read if a separate error stream is requested fromthe server. Otherwise, null will be returned. |
| getInputStream | | public InputStream getInputStream()(Code) | | Returns the InputStream from which the standard outputof the remote
process can be read. The input stream will only be set after a
successful rexec() invocation.
The InputStream from which the standard output of the remoteprocess can be read. |
| getOutputStream | | public OutputStream getOutputStream()(Code) | | Returns the OutputStream through which the standard input of the remote
process can be written. The output stream will only be set after a
successful rexec() invocation.
The OutputStream through which the standard input of the remoteprocess can be written. |
| isRemoteVerificationEnabled | | final public boolean isRemoteVerificationEnabled()(Code) | | Return whether or not verification of the remote host providing a
separate error stream is enabled. The default behavior is for
verification to be enabled.
True if verification is enabled, false if not. |
| rexec | | public void rexec(String username, String password, String command, boolean separateErrorStream) throws IOException(Code) | | Remotely executes a command through the rexecd daemon on the server
to which the RExecClient is connected. After calling this method,
you may interact with the remote process through its standard input,
output, and error streams. You will typically be able to detect
the termination of the remote process after reaching end of file
on its standard output (accessible through
RExecClient.getInputStream getInputStream() . Disconnecting
from the server or closing the process streams before reaching
end of file will not necessarily terminate the remote process.
If a separate error stream is requested, the remote server will
connect to a local socket opened by RExecClient, providing an
independent stream through which standard error will be transmitted.
RExecClient will do a simple security check when it accepts a
connection for this error stream. If the connection does not originate
from the remote server, an IOException will be thrown. This serves as
a simple protection against possible hijacking of the error stream by
an attacker monitoring the rexec() negotiation. You may disable this
behavior with
RExecClient.setRemoteVerificationEnabled setRemoteVerificationEnabled() .
Parameters:
username - The account name on the server through which to executethe command.
Parameters:
password - The plain text password of the user account.
Parameters:
command - The command, including any arguments, to execute.
Parameters:
separateErrorStream - True if you would like the standard errorto be transmitted through a different stream than standard output.False if not.
exception:
IOException - If the rexec() attempt fails. The exceptionwill contain a message indicating the nature of the failure. |
| setRemoteVerificationEnabled | | final public void setRemoteVerificationEnabled(boolean enable)(Code) | | Enable or disable verification that the remote host connecting to
create a separate error stream is the same as the host to which
the standard out stream is connected. The default is for verification
to be enabled. You may set this value at any time, whether the
client is currently connected or not.
Parameters:
enable - True to enable verification, false to disable verification. |
| Methods inherited from org.apache.commons.net.SocketClient | protected void _connectAction_() throws IOException(Code)(Java Doc)
public void connect(InetAddress host, int port) throws SocketException, IOException(Code)(Java Doc)
public void connect(String hostname, int port) throws SocketException, IOException(Code)(Java Doc)
public void connect(InetAddress host, int port, InetAddress localAddr, int localPort) throws SocketException, IOException(Code)(Java Doc)
public void connect(String hostname, int port, InetAddress localAddr, int localPort) throws SocketException, IOException(Code)(Java Doc)
public void connect(InetAddress host) throws SocketException, IOException(Code)(Java Doc)
public void connect(String hostname) throws SocketException, IOException(Code)(Java Doc)
public void disconnect() throws IOException(Code)(Java Doc)
public int getDefaultPort()(Code)(Java Doc)
public int getDefaultTimeout()(Code)(Java Doc)
public InetAddress getLocalAddress()(Code)(Java Doc)
public int getLocalPort()(Code)(Java Doc)
public InetAddress getRemoteAddress()(Code)(Java Doc)
public int getRemotePort()(Code)(Java Doc)
public int getSoLinger() throws SocketException(Code)(Java Doc)
public int getSoTimeout() throws SocketException(Code)(Java Doc)
public boolean getTcpNoDelay() throws SocketException(Code)(Java Doc)
public boolean isConnected()(Code)(Java Doc)
public void setDefaultPort(int port)(Code)(Java Doc)
public void setDefaultTimeout(int timeout)(Code)(Java Doc)
public void setSoLinger(boolean on, int val) throws SocketException(Code)(Java Doc)
public void setSoTimeout(int timeout) throws SocketException(Code)(Java Doc)
public void setSocketFactory(SocketFactory factory)(Code)(Java Doc)
public void setTcpNoDelay(boolean on) throws SocketException(Code)(Java Doc)
public boolean verifyRemote(Socket socket)(Code)(Java Doc)
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