there's something strange in my client/server socket using RSA. If i test it on localhost, everithing goes fine, but if i put client on a pc and server on othe pc, something gone wrong.

Client after call connect, call a method for public keys exchange with server. This part of code works fine. After this, client send a request to server:

strcpy(send_pack->op, "help\n");
RSA_public_encrypt(strlen(send_pack->op), send_pack->op, 
        encrypted_send->op, rsa_server, padding);

rw_value = write(server, encrypted_send, sizeof (encrypted_pack));
if (rw_value == -1) {
    stampa_errore(write_error);
    close(server);
    exit(1);
}
if (rw_value == 0) {
    stampa_errore(no_response);
    close(server);
    exit(1);
}
printf("---Help send, waiting for response\n");
set_alarm();
rw_value = read(server, encrypted_receive, sizeof (encrypted_pack));
alarm(0);
if (rw_value == -1) {
    stampa_errore(read_error);
    exit(1);
}
if (rw_value == 0) {
    stampa_errore(no_response);
    close(server);
    exit(1);
}
RSA_private_decrypt(RSA_size(rsa), encrypted_receive->message, 
        receive_pack->message, rsa, padding);
printf("%s\n", receive_pack->message);
return;
}

but when server try to decrypt the receive message on server side, the "help" string doesn't appear. This happen only on the net, on localhost the same code works fine...

EDIT:

typedef struct pack1 {
unsigned char user[encrypted_size];
unsigned char password[encrypted_size];
unsigned char op[encrypted_size];
unsigned char obj[encrypted_size];
unsigned char message[encrypted_size];
int id;
}encrypted_pack;

encrypted_size is 512, and padding used is RSA_PKCS1_PADDING