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Re: ACK is being sent with a sequence of 0 every time.
From: James Rogers <jamesmrogers () gmail com>
Date: Mon, 25 Jun 2012 14:40:59 -0400

Still recommending we fix the acks always sending with a 0 sequence
number bug with a patch like this:

jrogers () jrogers-1015PX:~/nmap/source/original/nmap$ svn diff *.cc
Index: scan_engine.cc
--- scan_engine.cc      (revision 29046)
+++ scan_engine.cc      (working copy)
@@ -3369,9 +3369,10 @@
        comes back (possibly incremented) in the ACK field of responses. But if
        our probe has the ACK flag set, the response reflects our own ACK number
        instead. */
-    if (pspec->pd.tcp.flags & TH_ACK)
+    if (pspec->pd.tcp.flags & TH_ACK) {
       ack = seq32_encode(USI, tryno, pingseq);
-    else
+      seq = get_random_u32();
+    } else
       seq = seq32_encode(USI, tryno, pingseq);

     if (pspec->pd.tcp.flags & TH_SYN) {

This way when we send an ack we also fill in the seq with something
other than 0.

On Wed, Jun 13, 2012 at 4:33 PM, James Rogers <jamesmrogers () gmail com> wrote:
I see this sequence number issue as different  than the spurious port
closed bug, that I why I broke it up in a different email.

On Wed, Jun 13, 2012 at 4:16 PM, David Fifield <david () bamsoftware com> wrote:
On Wed, Jun 13, 2012 at 03:58:28PM -0400, James Rogers wrote:
Thanks for the other comment location and the revision log number.  I
will read that.

I'll try  get_random_u32() there to see what effect that has.

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