This document outlines a server and client for remote command execution. The server runs on a specified port, accepts connections from clients, and executes commands sent by the client using a bash process. It returns the output to the client. The client connects to the server, takes input from the user and sends it to the server, and prints the response until it receives a "bye" message. References are provided for the source code and presentation platform used.

1. Introduction The Server The Echo Client References
REMOTE COMMAND EXECUTION
Muhammad Adil Raja
Roaming Researchers, R .
November 18, 2015

2. Introduction The Server The Echo Client References
OUTLINE
1 INTRODUCTION
2 THE SERVER
3 THE ECHO CLIENT
4 REFERENCES

3. Introduction The Server The Echo Client References
OUTLINE
1 INTRODUCTION
2 THE SERVER
3 THE ECHO CLIENT
4 REFERENCES

4. Introduction The Server The Echo Client References
OUTLINE
1 INTRODUCTION
2 THE SERVER
3 THE ECHO CLIENT
4 REFERENCES

5. Introduction The Server The Echo Client References
OUTLINE
1 INTRODUCTION
2 THE SERVER
3 THE ECHO CLIENT
4 REFERENCES

6. Introduction The Server The Echo Client References
INTRODUCTION

7. Introduction The Server The Echo Client References
THE SERVER I
/∗
∗ Copyright ( c ) 2013, Oracle and / or i t s a f f i l i a t e s . A l l r i g h t s reserved .
∗
∗ R e d i s t r i b u t i o n and use in source and binary forms , with or without
∗ modification , are permitted provided that the f o l l o w i n g conditions
∗ are met :
∗
∗ − Redistributions of source code must r e t a i n the above copyright
∗ notice , t h i s l i s t of conditions and the f o l l o w i n g disclaimer .
∗
∗ − Redistributions in binary form must reproduce the above copyright
∗ notice , t h i s l i s t of conditions and the f o l l o w i n g disclaimer in the
∗ documentation and / or other materials provided with the d i s t r i b u t i o n .
∗
∗ − Neither the name of Oracle or the names of i t s
∗ c o n t r i b u t o r s may be used to endorse or promote products derived
∗ from t h i s software without s p e c i f i c p r i o r w r i t t e n permission .
∗
∗ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
∗ IS " AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
∗ THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
∗ PURPOSE ARE DISCLAIMED . IN NO EVENT SHALL THE COPYRIGHT OWNER OR
∗ CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT , INCIDENTAL , SPECIAL ,
∗ EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
∗ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
∗ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
∗ LIABILITY , WHETHER IN CONTRACT, STRICT LIABILITY , OR TORT (INCLUDING
∗ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
∗ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

8. Introduction The Server The Echo Client References
THE SERVER II
∗/
import java . net . ∗ ;
import java . io . ∗ ;
public class TelnetServer {
public static void main ( String [ ] args ) throws IOException {
i f ( args . length != 1) {
System . err . p r i n t l n ( "Usage : java EchoServer <port number>" ) ;
System . e x i t ( 1 ) ;
}
int portNumber = Integer . parseInt ( args [ 0 ] ) ;
try (
ServerSocket serverSocket =
new ServerSocket ( Integer . parseInt ( args [ 0 ] ) ) ;
Socket clientSocket = serverSocket . accept ( ) ;
P r i n t W r i t e r out =
new P r i n t W r i t e r ( clientSocket . getOutputStream ( ) , true ) ;
BufferedReader in = new BufferedReader (
new InputStreamReader ( clientSocket . getInputStream ( ) ) ) ;
) {
String inputLine ;
String n u l l S t r =null ;
while ( ( inputLine = in . readLine ( ) ) != null ) {
ProcessBuilder processB=new ProcessBuilder ( " bash " , "−c " , inputLine ) ;
processB . redirectErrorStream ( true ) ;

9. Introduction The Server The Echo Client References
THE SERVER III
Process process = processB . s t a r t ( ) ;
BufferedReader br = new BufferedReader (
new InputStreamReader ( process . getInputStream ( ) ) ) ;
/ / BufferedReader errorReader = new BufferedReader (
/ / new InputStreamReader ( process . getErrorStream ( ) ) ) ;
while ( ( inputLine=br . readLine ( ) ) ! = null ) {
out . p r i n t l n ( inputLine ) ;
System . out . p r i n t l n ( " Log : "+ inputLine ) ;
}
out . p r i n t l n ( " bye " ) ;
out . flush ( ) ;
System . out . p r i n t l n ( "Bye Input ! " ) ;
System . out . p r i n t l n ( "Bye Error ! " ) ;
br . close ( ) ;
process . destroy ( ) ;
/ / out . p r i n t l n ( " Bye : " ) ;
}
} catch ( IOException e ) {
System . out . p r i n t l n ( " Exception caught when t r y i n g to l i s t e n on port "
+ portNumber + " or l i s t e n i n g f o r a connection " ) ;
System . out . p r i n t l n ( e . getMessage ( ) ) ;
}
}
}

10. Introduction The Server The Echo Client References
THE CLIENT I
/∗
∗ Copyright ( c ) 1995, 2013, Oracle and / or i t s a f f i l i a t e s . A l l r i g h t s reserved .
∗
∗ R e d i s t r i b u t i o n and use in source and binary forms , with or without
∗ modification , are permitted provided that the f o l l o w i n g conditions
∗ are met :
∗
∗ − Redistributions of source code must r e t a i n the above copyright
∗ notice , t h i s l i s t of conditions and the f o l l o w i n g disclaimer .
∗
∗ − Redistributions in binary form must reproduce the above copyright
∗ notice , t h i s l i s t of conditions and the f o l l o w i n g disclaimer in the
∗ documentation and / or other materials provided with the d i s t r i b u t i o n .
∗
∗ − Neither the name of Oracle or the names of i t s
∗ c o n t r i b u t o r s may be used to endorse or promote products derived
∗ from t h i s software without s p e c i f i c p r i o r w r i t t e n permission .
∗
∗ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
∗ IS " AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
∗ THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
∗ PURPOSE ARE DISCLAIMED . IN NO EVENT SHALL THE COPYRIGHT OWNER OR
∗ CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT , INCIDENTAL , SPECIAL ,
∗ EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
∗ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
∗ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
∗ LIABILITY , WHETHER IN CONTRACT, STRICT LIABILITY , OR TORT (INCLUDING
∗ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
∗ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

11. Introduction The Server The Echo Client References
THE CLIENT II
∗/
import java . io . ∗ ;
import java . net . ∗ ;
public class TelnetClient {
public static void main ( String [ ] args ) throws IOException {
i f ( args . length != 2) {
System . err . p r i n t l n (
"Usage : java TelnetClient <host name> <port number>" ) ;
System . e x i t ( 1 ) ;
}
String hostName = args [ 0 ] ;
int portNumber = Integer . parseInt ( args [ 1 ] ) ;
try (
Socket echoSocket = new Socket ( hostName , portNumber ) ;
P r i n t W r i t e r out =
new P r i n t W r i t e r ( echoSocket . getOutputStream ( ) , true ) ;
BufferedReader in =
new BufferedReader (
new InputStreamReader ( echoSocket . getInputStream ( ) ) ) ;
BufferedReader stdIn =
new BufferedReader (
new InputStreamReader ( System . in ) )
) {
String userInput , serverOutput ;

12. Introduction The Server The Echo Client References
THE CLIENT III
while ( ( userInput = stdIn . readLine ( ) ) != null ) {
out . p r i n t l n ( userInput ) ;
System . out . p r i n t l n ( " t e l n e t : " ) ;
while ( ! ( serverOutput=in . readLine ( ) ) . equals ( " bye " ) )
System . out . p r i n t l n ( serverOutput ) ;
System . out . p r i n t l n ( "Bye Client " ) ;
}
} catch ( UnknownHostException e ) {
System . err . p r i n t l n ( "Don ’ t know about host " + hostName ) ;
System . e x i t ( 1 ) ;
} catch ( IOException e ) {
System . err . p r i n t l n ( " Couldn ’ t get I /O f o r the connection to " +
hostName ) ;
System . e x i t ( 1 ) ;
}
}
}

13. Introduction The Server The Echo Client References
REFERENCES
The source code has been taken from
here.
This presentation has been produced with LATEX.
Frankfurt, monarcha.