title: Scapy SYN send on our own IP address
body: <p>I tried to send SYN packets on my local network and monitoring them with Wireshark and everything works just fine, except when i try to send a packet to my own ip address it "seems" to work because it says Sent 1 packet, but it is not really sent, i can't see the packet in Wireshark nor any answers to the packet. My setup is a computer A ( 192.168.0.1 ) with a TCP Socket Server listening on port 40508, and a computer B ( 192.168.0.2 ).</p>
  
  <p>On Computer B i test:</p>
  
  <pre><code>ip=IP(src="192.168.0.2",dst="192.168.0.1")  
  SYN=TCP(sport=40508,dport=40508,flags="S",seq=12345)
  send(ip/SYN)
  </code></pre>
  
  <p>It works fine, i see the SYN packet on Wireshark and the SYN/ACK response from 192.168.0.1</p>
  
  <p>On Computer A i test:</p>
  
  <pre><code>ip=IP(src="192.168.0.1",dst="192.168.0.2")  
  SYN=TCP(sport=40508,dport=40508,flags="S",seq=12345)
  send(ip/SYN)
  </code></pre>
  
  <p>It works fine too, i see the SYN packet and the RST/ACK ( there is no server listening on port 40508 on 192.168.0.2 so it sends a RST/ACK ) response from 192.168.0.2</p>
  
  <p>But when i try on Computer A :</p>
  
  <pre><code>ip=IP(src="192.168.0.2",dst="192.168.0.1")  
  SYN=TCP(sport=40508,dport=40508,flags="S",seq=12345)
  send(ip/SYN)
  </code></pre>
  
  <p>Nothing appears in Wireshark, as if the packet was never sent but it said like the other tests : Sent 1 packets. and returned no error whatsoever. If i run the same test on computer B and try to send a packet to its own IP address i got the same problem.</p>
  
  <p>For my program i really need to send a SYN packet to my own IP address, is there a way to do that or is it impossible ?</p>
  
  <p>Thanks in advance,</p>
  
  <p>Nolhian</p>