Index: sys/netinet/netdump/netdump_client.c
===================================================================
--- sys/netinet/netdump/netdump_client.c
+++ sys/netinet/netdump/netdump_client.c
@@ -114,6 +114,8 @@

 /* Must be at least as big as the chunks dumpsys() gives us. */
 static unsigned char nd_buf[MAXDUMPPGS * PAGE_SIZE];
+static off_t nd_tx_offset;
+static off_t nd_buf_offset;
 static uint32_t nd_seqno;
 static int dump_failed, have_gw_mac;
 static void (*drv_if_input)(struct ifnet *, struct mbuf *);
@@ -944,6 +946,12 @@
 	    virtual, (uintmax_t)offset, length);

 	if (virtual == NULL) {
+		if (nd_buf_offset != 0) {
+			error = netdump_send(NETDUMP_VMCORE, nd_tx_offset, nd_buf, nd_buf_offset);
+			if (error != 0) {
+				dump_failed = 1;
+			}
+		}
 		if (dump_failed != 0)
 			printf("failed to dump the kernel core\n");
 		else if (netdump_send(NETDUMP_FINISHED, 0, NULL, 0) != 0)
@@ -956,12 +964,19 @@
 	if (length > sizeof(nd_buf))
 		return (ENOSPC);

-	memmove(nd_buf, virtual, length);
-	error = netdump_send(NETDUMP_VMCORE, offset, nd_buf, length);
-	if (error != 0) {
-		dump_failed = 1;
-		return (error);
+	if (nd_buf_offset + length > sizeof(nd_buf)) {
+		error = netdump_send(NETDUMP_VMCORE, nd_tx_offset, nd_buf, nd_buf_offset);
+		if (error != 0) {
+			dump_failed = 1;
+			return (error);
+		}
+		nd_buf_offset = 0;
+		nd_tx_offset = offset;
 	}
+
+	memmove(nd_buf + nd_buf_offset, virtual, length);
+	nd_buf_offset += length;
+
 	return (0);
 }