Remote Command Execution Using Socket System Calls

Computer Network Lab Manual / Remote Command Execution Using Socket System Calls

Program Name

Write a C Program for Remote Command Execution Using Socket System Calls .

Theory


Server	Compiling	    cc s.c -o sobj
Server  Running	        ./ sobj&
Client	Compiling	    cc c.c
Client	Running	        ./a.out

Program Code


//Server
#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/file.h>
#include<string.h>

main()
{
intsockfd,clilen,nsockfd,i,j,fd;	
structsockaddr_insa,ca;
charstr[20],buff[5000];
sockfd = socket(AF_INET,SOCK_STREAM,0);
if(sockfd<0)
{
perror("socket not created");
exit(0);
}
sa.sin_family=AF_INET;
sa.sin_port=htons(6135);
sa.sin_addr.s_addr=inet_addr("127.0.0.1");
j=bind(sockfd,(structsockaddr *)&sa, sizeof(sa));
if(j<0)
{
perror("connection not created");
exit(0);
}
printf("%d\n",j);
listen(sockfd,5);
while(1)
{
clilen=sizeof(ca);
nsockfd=accept(sockfd,(structsockaddr *)&ca,&clilen);
recv(nsockfd,str,sizeof(str),0);
system(str);
fd=open("f2.txt",O_RDWR);
read(fd,buff,sizeof(buff));

send(nsockfd,buff,sizeof(buff),0);
for(i=0;i<sizeof(buff);i++)
buff[i]='\0';
}
close(nsockfd);
close(sockfd);
}



// remote command execution using sockets - client

#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<string.h>
#include<stdlib.h>

main()
{
intsockfd,j;
structsockaddr_insa;
char name[20],buff1[5000];
sockfd=socket(AF_INET,SOCK_STREAM,0);
if(sockfd<0)
{
perror("socket not created");
exit(0);
}
sa.sin_family=AF_INET;
sa.sin_port=htons(6135);
sa.sin_addr.s_addr=inet_addr("127.0.0.1");
j=connect(sockfd,(structsockaddr *)&sa,sizeof(sa));
if(j<0)
{
perror("connection not created");
exit(0);
}
printf("Enter a command : ");
scanf("%s",name);
strcat(name,">f2.txt");
send(sockfd,name,20,0);
recv(sockfd,buff1,250,0);
printf("The command contains\n %s",buff1);
close(sockfd);
}

Input:
Enter a command : ls

Output:
List of files

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