diff --git a/flexnbd.c b/flexnbd.c
index b130d52..bc3e2d4 100644
--- a/flexnbd.c
+++ b/flexnbd.c
@@ -14,10 +14,14 @@
 void syntax()
 {
 	fprintf(stderr, 
-	"Syntax: flexnbd serve  <IP address> <port> <file> [ip addresses ...]\n"
+	"Syntax: flexnbd serve  <listen IP address> <port> <file> \\\n"
+	"                          [full path to control socket] \\\n"
+	"                          [allowed connection addresses ...]\n"
+	"        flexnbd mirror <control socket> <dst IP address> <dst port>\n"
+	"        flexnbd status <control socket>\n"
 	"        flexnbd read   <IP address> <port> <offset> <length> > data\n"
 	"        flexnbd write  <IP address> <port> <offset> <length> < data\n"
-	"        flexnbd write  <IP address> <port> <offset> <data file>\n"
+	"        flexnbd write  <IP address> <port> <offset> <file to write>\n"
 	);
 	exit(1);
 }
@@ -102,7 +106,7 @@ void params_serve(
 	char* s_port, 
 	char* s_file,
 	int acl_entries,
-	char** s_acl_entries
+	char** s_acl_entries /* first may actually be path to control socket */
 )
 {
 	int parsed;
@@ -120,6 +124,12 @@ void params_serve(
 		SERVER_ERROR("Couldn't parse server address '%s' (use 0 if "
 		  "you want to bind to all IPs)", s_ip_address);
 	
+	if (acl_entries > 0 && s_acl_entries[0][0] == '/') {
+		out->control_socket_name = s_acl_entries[0];
+		s_acl_entries++;
+		acl_entries--;		
+	}
+	
 	out->acl_entries = acl_entries;
 	parsed = parse_acl(&out->acl, acl_entries, s_acl_entries);
 	if (parsed != acl_entries)
diff --git a/ioutil.c b/ioutil.c
index af2e753..73f8665 100644
--- a/ioutil.c
+++ b/ioutil.c
@@ -44,7 +44,7 @@ char* build_allocation_map(int fd, off64_t size, int resolution)
 	fiemap->fm_extent_count = fiemap->fm_mapped_extents;
 	fiemap->fm_mapped_extents = 0;
 
-	if (ioctl(fd, FS_IOC_FIEMAP, fiemap) < -1)
+	if (ioctl(fd, FS_IOC_FIEMAP, fiemap) < 0)
 		return NULL;
 	
 	for (i=0;i<fiemap->fm_mapped_extents;i++) {
diff --git a/params.h b/params.h
index 8bbd333..d55ee26 100644
--- a/params.h
+++ b/params.h
@@ -27,9 +27,10 @@ struct mode_serve_params {
 	struct ip_and_mask** acl;
 	char*                filename;
 	int                  tcp_backlog;
+	char*                control_socket_name;
 	
 	int                  server;
-	int                  threads;
+	int                  control;	
 	
 	char*                block_allocation_map;
 };
diff --git a/serve.c b/serve.c
index 0a4c5f7..7aa0441 100644
--- a/serve.c
+++ b/serve.c
@@ -7,6 +7,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
+#include <sys/un.h>
 #include <fcntl.h>
 
 #include <string.h>
@@ -315,7 +316,7 @@ int is_included_in_acl(int list_length, struct ip_and_mask** list, struct sockad
 	return 0;
 }
 
-void serve_open_socket(struct mode_serve_params* params)
+void serve_open_server_socket(struct mode_serve_params* params)
 {
 	params->server = socket(PF_INET, SOCK_STREAM, 0);
 	
@@ -334,6 +335,28 @@ void serve_open_socket(struct mode_serve_params* params)
 	);
 }
 
+void serve_open_control_socket(struct mode_serve_params* params)
+{
+	struct sockaddr_un bind_address;
+	
+	if (!params->control_socket_name)
+		return;
+
+	params->control = socket(AF_UNIX, SOCK_DGRAM, 0);
+	SERVER_ERROR_ON_FAILURE(params->control,
+	  "Couldn't create control socket");
+	
+	memset(&bind_address, 0, sizeof(bind_address));
+	bind_address.sun_family = AF_UNIX;
+	strcpy(bind_address.sun_path, params->control_socket_name);
+	
+	SERVER_ERROR_ON_FAILURE(
+		bind(params->control, &bind_address, sizeof(bind_address)),
+		"Couldn't bind control socket to %s",
+		params->control_socket_name
+	);
+}
+
 void serve_accept_loop(struct mode_serve_params* params) 
 {
 	while (1) {
@@ -384,7 +407,8 @@ void serve_init_allocation_map(struct mode_serve_params* params)
 
 void do_serve(struct mode_serve_params* params)
 {
-	serve_open_socket(params);
+	serve_open_server_socket(params);
+	serve_open_control_socket(params);
 	serve_init_allocation_map(params);
 	serve_accept_loop(params);
 }