org.apache.commons.net.bsd
public class RCommandClient extends RExecClient
As with virtually all of the client classes in org.apache.commons.net, this
class derives from SocketClient. But it overrides most of its connection
methods so that the local Socket will originate from an acceptable
rshell port. The way to use RCommandClient is to first connect
to the server, call the rcommand()
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 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
getInputStream()
. However, it is
possible to tell the rshd daemon to return the standard error
stream over a separate connection, readable from the input stream
returned by getErrorStream()
. You
can specify that a separate connection should be created for standard
error by setting the boolean separateErrorStream
parameter of rcommand()
to true
.
The standard input of the remote process can be written to through
the output stream returned by
getOutputStream()
.
See Also: SocketClient RExecClient
Field Summary | |
---|---|
static int | DEFAULT_PORT
The default rshell port. |
static int | MAX_CLIENT_PORT
The largest port number an rcmd client may use. |
static int | MIN_CLIENT_PORT
The smallest port number an rcmd client may use. |
Constructor Summary | |
---|---|
RCommandClient()
The default RCommandClient constructor. |
Method Summary | |
---|---|
void | connect(InetAddress host, int port, InetAddress localAddr)
Opens a Socket connected to a remote host at the specified port and
originating from the specified local address using a port in a range
acceptable to the BSD rshell daemon.
|
void | connect(InetAddress host, int port)
Opens a Socket connected to a remote host at the specified port and
originating from the current host at a port in a range acceptable
to the BSD rshell daemon.
|
void | connect(String hostname, int port)
Opens a Socket connected to a remote host at the specified port and
originating from the current host at a port in a range acceptable
to the BSD rshell daemon.
|
void | connect(String hostname, int port, InetAddress localAddr)
Opens a Socket connected to a remote host at the specified port and
originating from the specified local address using a port in a range
acceptable to the BSD rshell daemon.
|
void | connect(InetAddress host, int port, InetAddress localAddr, int localPort)
Opens a Socket connected to a remote host at the specified port and
originating from the specified local address and port. |
void | connect(String hostname, int port, InetAddress localAddr, int localPort)
Opens a Socket connected to a remote host at the specified port and
originating from the specified local address and port. |
void | rcommand(String localUsername, String remoteUsername, String command, boolean separateErrorStream)
Remotely executes a command through the rshd daemon on the server
to which the RCommandClient is connected. |
void | rcommand(String localUsername, String remoteUsername, String command)
Same as
rcommand(localUsername, remoteUsername, command, false);
|
DEFAULT_PORT
.
_connectAction_()
is called to perform connection initialization actions.
Parameters: host The remote host. port The port to connect to on the remote host. localAddr The local address to use.
Throws: SocketException If the socket timeout could not be set. BindException If all acceptable rshell ports are in use. IOException If the socket could not be opened. In most cases you will only want to catch IOException since SocketException is derived from it.
_connectAction_()
is called to perform connection initialization actions.
Parameters: host The remote host. port The port to connect to on the remote host.
Throws: SocketException If the socket timeout could not be set. BindException If all acceptable rshell ports are in use. IOException If the socket could not be opened. In most cases you will only want to catch IOException since SocketException is derived from it.
_connectAction_()
is called to perform connection initialization actions.
Parameters: hostname The name of the remote host. port The port to connect to on the remote host.
Throws: SocketException If the socket timeout could not be set. BindException If all acceptable rshell ports are in use. IOException If the socket could not be opened. In most cases you will only want to catch IOException since SocketException is derived from it. UnknownHostException If the hostname cannot be resolved.
_connectAction_()
is called to perform connection initialization actions.
Parameters: hostname The remote host. port The port to connect to on the remote host. localAddr The local address to use.
Throws: SocketException If the socket timeout could not be set. BindException If all acceptable rshell ports are in use. IOException If the socket could not be opened. In most cases you will only want to catch IOException since SocketException is derived from it.
MIN_CLIENT_PORT
and
MAX_CLIENT_PORT
or an IllegalArgumentException will
be thrown.
Before returning, _connectAction_()
is called to perform connection initialization actions.
Parameters: host The remote host. port The port to connect to on the remote host. localAddr The local address to use. localPort The local port to use.
Throws: SocketException If the socket timeout could not be set. IOException If the socket could not be opened. In most cases you will only want to catch IOException since SocketException is derived from it. IllegalArgumentException If an invalid local port number is specified.
MIN_CLIENT_PORT
and
MAX_CLIENT_PORT
or an IllegalArgumentException will
be thrown.
Before returning, _connectAction_()
is called to perform connection initialization actions.
Parameters: hostname The name of the remote host. port The port to connect to on the remote host. localAddr The local address to use. localPort The local port to use.
Throws: SocketException If the socket timeout could not be set. IOException If the socket could not be opened. In most cases you will only want to catch IOException since SocketException is derived from it. UnknownHostException If the hostname cannot be resolved. IllegalArgumentException If an invalid local port number is specified.
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 RCommandClient, providing an
independent stream through which standard error will be transmitted.
The local socket must originate from a secure port (512 - 1023),
and rcommand() ensures that this will be so.
RCommandClient will also 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
setRemoteVerificationEnabled()
.
Parameters: localUsername The user account on the local machine that is requesting the command execution. remoteUsername The account name on the server through which to execute the command. command The command, including any arguments, to execute. separateErrorStream True if you would like the standard error to be transmitted through a different stream than standard output. False if not.
Throws: IOException If the rcommand() attempt fails. The exception will contain a message indicating the nature of the failure.
rcommand(localUsername, remoteUsername, command, false);