Hi, Im trying to write a syn-scanner in perl and Im struck in not being able to get the return packet with syn-ack bits set from the destination host. The problem is Im getting a packet with source and destination IP as loop back address (127.0.0.1). and only the syn bit set. I dont know where I went wrong. I have generated the packet setting the syn_flag_bit=1. I have created two socket handles s_sock and r_sock for sending and recieving respectively with protocol number as 6 for both of them.

The send() command also works well and I get the number of bits sent (40 bytes, tcp and ip header together) as the return value. The segment looks like...

                                                                      
+                    ......
.....
....
send($s_sock,$packet,0,$dest);
$read = new IO::Select();
$read->add($r_sock);
($return)=IO::Select->select($read,undef,undef,5);
                                                                      
+                                                      if ($return)
{
recv($r_sock,$buff,256,0);
........
.....
...
}
[download]

can u please tell me what is happening and why i get that return packet with loop back ip?

thanks, Abaya.

Edited by Chady -- minor formatting and code tags.