trouble with executing a server/client c based program

i was trying to execute a simple server/client c based application, i've executed the server on machine A and client on machine B (both running on linux ),even though the code is correct (i didn't write it down my self but many people said it works fine) the client keeps telling me it couldn't connect to the server.can anyone please tell me what is the problem
PS: i used both external and internal ip adresses of machine A,still nothing, but when i execute both client and server on the same machine and use 127.0.0.1 or my internal ip adress it works correctly !!!
here is the server code:

#include <stdio.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
int main(int argc,char *argv[])
{
    int simpleport=0;
    int simplesocket=0;
    int returnstatus;
    int simplechildsocket;
    struct sockaddr_in simpleserver;
    char buffer[256]="";
    if(argc!=2)
    {
        fprintf(stderr,"usage: %s  <port number>\n",argv[0]);
        exit(1);
    }
    /*create the socket*/
    simplesocket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
    if(simplesocket<0)
    {
        fprintf(stderr,"socket not created!\n");
        exit(1);
    }
    else
    fprintf(stderr,"socket created successfully\n");
    memset(&simpleserver,0,sizeof(simpleserver));
    simpleport=atoi(argv[1]);
    //create simpleserver
    simpleserver.sin_family=AF_INET;
    simpleserver.sin_addr.s_addr=htonl(INADDR_ANY);
    simpleserver.sin_port=htons(simpleport);
    //the binding process
    returnstatus=bind(simplesocket,(struct sockaddr*)&simpleserver,sizeof(simpleserver));
    if(!returnstatus)
    fprintf(stderr,"bind completed!\n");
    else
    {
        fprintf(stderr,"could not bind to socket!\n");
        close(simplesocket);
        exit(1);
    }
    fprintf(stderr,"%s\n",(char *)inet_ntoa(simpleserver.sin_addr));
    //listen on socket
    returnstatus=listen(simplesocket,5);
    if(returnstatus)
    {
        fprintf(stderr,"could not listen on socket\n");
        close(simplesocket);
        exit(1);
    }
    else
    fprintf(stderr,"listening on socket!\n");
    while(1)
    {
        struct sockaddr_in simpleclient= {0};
        int clientnamelength=sizeof(simpleclient);
        simplechildsocket=accept(simplesocket,(struct sockaddr *)&simpleclient,&clientnamelength);
        if(simplechildsocket<0)
        {
            fprintf(stderr,"could not accept connections!\n");
            close(simplechildsocket);
            exit(1);
        }
        else
        fprintf(stderr,"connection established!\n");
        char clientname[20];
        if(inet_ntop(AF_INET,&simpleclient.sin_addr.s_addr,clientname,sizeof(clientname))!=NULL)
        fprintf(stderr,"handling client %s  %d\n",clientname,ntohs(simpleclient.sin_port));
        else
        {
            fprintf(stderr,"could not receive client adress!\n");
            close(simplechildsocket);
            exit(1);
        }
	sleep(20);
        returnstatus=recv(simplechildsocket,buffer,255,0);
        if(returnstatus<0)
        {
            fprintf(stderr,"recv() failed!");
            close(simplechildsocket);
            exit(1);
        }
        int totalbytesent=0;
        while(returnstatus>0)
        {
            totalbytesent=send(simplechildsocket,buffer,returnstatus,0);
            if(totalbytesent<0)
            {
                fprintf(stderr,"send() failed");
                close(simplechildsocket);
                exit(1);
            }
            else if(totalbytesent!=returnstatus)
            {
                fprintf(stderr,"sent unexpectd number of bytes!\n");
                close(simplechildsocket);
                exit(1);
            }
            returnstatus=recv(simplechildsocket,buffer,255,0);
            if(returnstatus<0)
            {
                fprintf(stderr,"revc() failed\n");
                close(simplechildsocket);
                exit(1);
            }
        }
        close(simplechildsocket);
    }
    close(simplesocket);
    return 0;
}

and the client code:

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>
int main(int argc,char *argv[])
{
    int simplesocket;
    int returnstatus;
    int portnumber;
    char *buffer, *servip;
    struct sockaddr_in simpleserver;
    size_t addr_len;
    if(argc!=4)
    {
        fprintf(stderr,"usage : %s <server adress> <echo word>  <server port>\n",argv[0]);
        exit(1);
    }
    buffer=(char*)malloc(strlen(argv[2])*sizeof(char));
    if(!buffer)
    {
        fprintf(stderr,"no free memory space!\n");
        exit(1);
    }
    simplesocket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
    if(simplesocket<0)
    {
        fprintf(stderr,"could not create socket!\n");
        exit(1);
    }
    else
    fprintf(stderr,"socket created successfully!\n");
     memset(&simpleserver,0,sizeof(simpleserver));
    portnumber=atoi (argv[3]);
    simpleserver.sin_port=htons(portnumber);
    servip=argv[1];
    returnstatus=inet_pton(AF_INET,servip,&simpleserver.sin_addr.s_addr);
    if(returnstatus==0)
    {
        fprintf(stderr,"inet_pton()failed,invalid IP adress!\n");
        close(simplesocket);
	exit(1);
    }
    else
    if(returnstatus<0)
    {
 	fprintf(stderr,"inet_pton()failed");
	close(simplesocket);
	exit(1);
    }
    simpleserver.sin_family=AF_INET;
    returnstatus=connect(simplesocket,(struct sockaddr*)&simpleserver,sizeof(simpleserver));
    if(returnstatus<0)
    {
        fprintf(stderr,"could not connect to  server!\n");
        close (simplesocket);
        exit(1);
    }
    else
    fprintf(stderr,"connect successfully!\n");
    strcpy(buffer,argv[2]);
    returnstatus=send(simplesocket,buffer,strlen(buffer),0);
    if(returnstatus<0)
    {
	fprintf(stderr,"send() failed");
	close(simplesocket);
	exit(1);
     }
    else if(returnstatus!=strlen(buffer))
    {
	fprintf(stderr,"send(), sent unexpected number of bytes");
	close(simplesocket);
	exit(1);
    }
    int totalbytesreceived=0;
    int echostrlen=sizeof(buffer);
    strcpy(buffer,"");
    while(totalbytesreceived<echostrlen)
    {
	returnstatus=recv(simplesocket,buffer,255,0);
	if(returnstatus<0)
	{
		fprintf(stderr,"recv()failed");
		close(simplesocket);
		exit(1);
	}
	else if(returnstatus==0)
	{
		fprintf(stderr,"connection closed prematurely");
		close(simplesocket);
		exit(1);
	}
	totalbytesreceived+=returnstatus;
	buffer[returnstatus]='\0';
	fputs(buffer,stdout);
	}
	fputc('\n',stdout);
	fprintf(stderr,"ok");
    close(simplesocket);
    return 0;
}

Edited by tknmb1, 23 June 2010 - 08:43 AM.