Addition to private address space in NMAP-7.xx

[Bill Parker <wp02855 () gmail com>]

Subj: Add Link-Local Address Network Assignment Block (IPv4) to netutil.cc
in NMAP-7.xx

Hello All,

   In reviewing source code for NMAP 7.xx, I found in sub-directory
'libnetutil', file 'netutil.cc', that the private Microsoft Network
block 169.254.0.0/16 (which is assigned if MS DHCP fails for some
reason) is not included in the private IPv4 network listing in function
'isipprivate'.

In RFC 3927, the Internet Engineering Task Force has reserved the
address block 169.254.1.0 through 169.254.254.255] for link-local
addressing in Internet Protocol Version 4. Link-local addresses
are assigned to interfaces by host-internal, i.e. stateless,
address autoconfiguration when other means of address assignment
are not available.

The patch file(s) below addresses this issue:

--- netutil.cc.orig 2015-12-12 11:37:32.975996104 -0800
+++ netutil.cc 2015-12-12 11:46:38.785365668 -0800
@@ -1789,6 +1789,9 @@

 /* Determines whether the supplied address corresponds to a private,
  * non-Internet-routable address. See RFC1918 for details.
+ *
+ * Also checks for link-local addressing per RFC3927.
+ *
  * Returns 1 if the address is private or 0 otherwise. */
 int isipprivate(const struct sockaddr_storage *addr) {
   const struct sockaddr_in *sin;
@@ -1810,7 +1813,11 @@
     return 1;

   /* 172.16.0.0/12 */
-  if (i1 == 172 && i2 >= 16 && i2 <= 31)
+  if (i1 == 172 && (i2 >= 16 && i2 <= 31))
+    return 1;
+
+  /* 169.254.0.0/16 - RFC 3927 */
+  if (i1 == 192 && i2 == 254)
     return 1;

   /* 192.168.0.0/16 */

=======================================================================

--- netutil.h.orig 2015-12-12 11:48:11.294123055 -0800
+++ netutil.h 2015-12-12 11:48:52.351341217 -0800
@@ -433,6 +433,7 @@

 /* Determines whether the supplied address corresponds to a private,
  * non-Internet-routable address. See RFC1918 for details.
+ * Also checks for link-local addresses per RFC3927.
  * Returns 1 if the address is private or 0 otherwise. */
 int isipprivate(const struct sockaddr_storage *addr);

=======================================================================

I am attaching the patch file(s) to this report...

Comments, Questions, Complaints, Suggestions? :)

Bill Parker (wp02855 at gmail dot com)

Attachment: netutil.cc.patch
Description:

Attachment: netutil.h.patch
Description:

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