o Added initial SCTP port scanning support to Nmap. SCTP is

a layer 4 protocol used mostly for telephony related applications.
  This brings the following new features:
  o SCTP INIT chunk port scan (-sY): open ports return an INIT-ACK
    chunk, closed ones an ABORT chunk.  This is the SCTP equivalent
    of a TCP SYN stealth scan.
  o SCTP COOKIE-ECHO chunk port scan (-sZ): open ports are silent,
    closed ports return an ABORT chunk.
  o SCTP INIT chunk ping probes (-PY): host discovery using SCTP
    INIT chunk packets.
  o SCTP-specific IP protocol scan (-sO -p sctp).
  o SCTP-specific traceroute support (--traceroute).
  o The ability to use the deprecated Adler32 algorithm as specified
    in RFC 2960 instead of CRC32C from RFC 4960 (--adler32).
  o 42 well-known SCTP ports were added to the nmap-services file.
  Part of the work on SCTP support was kindly sponsored by
  Compass Security AG, Switzerland.  [Daniel Roethlisberger]

nmap.h

@@ -218,6 +218,11 @@ void *realloc();
 #include <arpa/inet.h>
 #endif
 
+/* For systems without SCTP in netinet/in.h, such as MacOS X */
+#ifndef IPPROTO_SCTP
+#define IPPROTO_SCTP 132
+#endif
+
 /* Keep assert() defined for security reasons */
 #undef NDEBUG
 
@@ -271,6 +276,9 @@ void *realloc();
                                             change this to 113 */
 #define DEFAULT_UDP_PROBE_PORT_SPEC "31338" /* The port UDP ping probes go to
                                                if unspecified by user */
+#define DEFAULT_SCTP_PROBE_PORT_SPEC "80" /* The port SCTP probes go to
+                                             if unspecified by
+                                             user */
 #define DEFAULT_PROTO_PROBE_PORT_SPEC "1,2,4" /* The IPProto ping probes to use
                                                  if unspecified by user */
 
@@ -290,6 +298,10 @@ void *realloc();
 #define MAX_UDP_SCAN_DELAY 1000
 #endif
 
+#ifndef MAX_SCTP_SCAN_DELAY
+#define MAX_SCTP_SCAN_DELAY 1000
+#endif
+
 /* Maximum number of extra hostnames, OSs, and devices, we
    consider when outputing the extra service info fields */
 #define MAX_SERVICE_INFO_FIELDS 5
@@ -339,6 +351,7 @@ void *realloc();
 #define PINGTYPE_UDP  512
 #define PINGTYPE_ARP 1024
 #define PINGTYPE_PROTO 2048
+#define PINGTYPE_SCTP_INIT 4096
 
 /* Empirically determined optimum combinations of different numbers of probes:
      -PE