Index: sys/netinet/netdump/netdump_client.c
===================================================================
--- sys/netinet/netdump/netdump_client.c
+++ sys/netinet/netdump/netdump_client.c
@@ -129,6 +129,9 @@
 	union kd_ip	 ndc_client;
 	union kd_ip	 ndc_gateway;
 	uint8_t		 ndc_af;
+	/* Runtime State */
+	off_t		 nd_tx_off;
+	size_t		 nd_buf_len;
 } nd_conf;
 #define	nd_server	nd_conf.ndc_server.in4
 #define	nd_client	nd_conf.ndc_client.in4
@@ -943,7 +946,25 @@
 	NETDDEBUGV("netdump_dumper(NULL, %p, NULL, %ju, %zu)\n",
 	    virtual, (uintmax_t)offset, length);
 
+	if (offset != 0 && nd_conf.nd_buf_len != 0 && nd_conf.nd_tx_off +
+	    nd_conf.nd_buf_len != offset) {
+		printf("\nnon-contiguous write: flushing buffer\n");
+		error = netdump_send(NETDUMP_VMCORE, nd_conf.nd_tx_off, nd_buf,
+		    nd_conf.nd_buf_len);
+		if (error != 0) {
+			dump_failed = 1;
+			return (error);
+		}
+	}
+
 	if (virtual == NULL) {
+		if (nd_conf.nd_buf_len != 0) {
+			error = netdump_send(NETDUMP_VMCORE, nd_conf.nd_tx_off, nd_buf, 
+			    nd_conf.nd_buf_len);
+			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 +977,20 @@
 	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_conf.nd_buf_len + length > sizeof(nd_buf)) {
+		error = netdump_send(NETDUMP_VMCORE, nd_conf.nd_tx_off, nd_buf, 
+		    nd_conf.nd_buf_len);
+		if (error != 0) {
+			dump_failed = 1;
+			return (error);
+		}
+		nd_conf.nd_buf_len = 0;
+		nd_conf.nd_tx_off = offset;
 	}
+
+	memmove(nd_buf + nd_conf.nd_buf_len, virtual, length);
+	nd_conf.nd_buf_len += length;
+
 	return (0);
 }