Index: sys/netinet/libalias/alias_sctp.c
===================================================================
--- sys/netinet/libalias/alias_sctp.c	(revision 188297)
+++ sys/netinet/libalias/alias_sctp.c	(working copy)
@@ -95,6 +95,9 @@
 #include <machine/in_cksum.h>
 #endif //#ifdef _KERNEL
 
+extern uint32_t (*update_crc32_ptr)(uint32_t, unsigned char *, unsigned int);
+extern uint32_t (*sctp_finalize_crc32_ptr)(uint32_t);
+
 /* ----------------------------------------------------------------------
  *                          FUNCTION PROTOTYPES
  * ----------------------------------------------------------------------
@@ -943,7 +946,10 @@
   
 	/* calculate SCTP header CRC32 */
 	sctp_hdr->checksum = 0;
-	sctp_hdr->checksum = sctp_finalize_crc32(update_crc32(0xffffffff, (unsigned char *) sctp_hdr, sctp_size));
+	if (update_crc32_ptr != NULL)
+		sctp_hdr->checksum = sctp_finalize_crc32_ptr(
+			update_crc32_ptr(0xffffffff, (unsigned char *) sctp_hdr, 
+			    sctp_size));
 
 	memcpy(sm->ip_hdr, ip, ip_size);
 
Index: sys/netinet/sctp_usrreq.c
===================================================================
--- sys/netinet/sctp_usrreq.c	(revision 188297)
+++ sys/netinet/sctp_usrreq.c	(working copy)
@@ -49,11 +49,13 @@
 #include <netinet/sctp_auth.h>
 #include <netinet/sctp_bsd_addr.h>
 #include <netinet/sctp_cc_functions.h>
+#include <netinet/sctp_crc32.h>
 #include <netinet/udp.h>
 
+/* alias sctp hooks. */
+extern uint32_t (*update_crc32_ptr)(uint32_t, unsigned char *, unsigned int);
+extern uint32_t (*sctp_finalize_crc32_ptr)(uint32_t);
 
-
-
 void
 sctp_init(void)
 {
@@ -88,13 +90,16 @@
 	bzero(&SCTP_BASE_VAR(packet_log_buffer), SCTP_PACKET_LOG_SIZE);
 #endif
 
-
+	update_crc32_ptr = update_crc32;
+	sctp_finalize_crc32_ptr = sctp_finalize_crc32;
 }
 
 void
 sctp_finish(void)
 {
 	sctp_pcb_finish();
+	update_crc32_ptr = NULL;
+	sctp_finalize_crc32_ptr = NULL;
 }
 
 
Index: sys/netinet/ip_input.c
===================================================================
--- sys/netinet/ip_input.c	(revision 188297)
+++ sys/netinet/ip_input.c	(working copy)
@@ -223,6 +223,10 @@
 
 static void	ip_freef(struct ipqhead *, struct ipq *);
 
+/* alias sctp hooks. */
+uint32_t (*update_crc32_ptr)(uint32_t, unsigned char *, unsigned int) = NULL;
+uint32_t (*sctp_finalize_crc32_ptr)(uint32_t) = NULL;
+
 /*
  * IP initialization: fill in IP protocol switch table.
  * All protocols not implemented in kernel go to raw IP protocol handler.