lkml.org 
[lkml]   [1998]   [Jan]   [23]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
DateThu, 22 Jan 1998 23:49:02 -0600 (CST)
FromJesse Off <>
SubjectTCP_LISTEN state oddity??
I'm a newbie to the linux kernel and have chosen for my first project a
lil' hack that try's to catch strobes.  In one the strobe programs,
'nmap', in particular, it probes the system by sending packets with FIN
set.  The kernel seems to respond by sending a reset to requests for ports
that aren't being listened to and simply drops the packet if the port is
being listened to.  Seemed kinda funny to me.  

As I said, I'm a newbie, and if this has some functionality I am not aware
of, please tell :).  I included a patch that seems to fix it on my system,
but am unaware if this breaks anything (hasn't yet on my system).


Cheers,
Jesse Off




--- tcp.backup  Thu Jan 22 23:04:01 1998
+++ tcp_input.c.orig    Thu Jan 22 23:11:32 1998
@@ -2420,7 +2420,6 @@
                                        }
                                }
 #endif
-tcp_send_reset(daddr,saddr,th,sk->prot,opt,dev,0, 255);
                        }

                        /*
@@ -2441,8 +2440,7 @@
                        if(th->rst || !th->syn || th->ack ||
ip_chk_addr(daddr)!=IS_MYADDR)
 #endif
                        {
-                               kfree_skb(skb, FREE_READ);
-                               return 0;
+                               goto no_tcp_socket;
                        }

                        /*


\
 
 \ /
  Last update: 2005-03-22 12:41    [from the cache]
©2003-2008