diff --git a/components/dfs/filesystems/lwip/lwip_netdb.c b/components/dfs/filesystems/lwip/lwip_netdb.c
index 68714742514cca0e619dd65ef12ab976cb7c4376..1e14dfb093f112f285db0a8786a416216c235f46 100644
--- a/components/dfs/filesystems/lwip/lwip_netdb.c
+++ b/components/dfs/filesystems/lwip/lwip_netdb.c
@@ -29,6 +29,7 @@ struct hostent *gethostbyname(const char *name)
 {
     return lwip_gethostbyname(name);
 }
+RTM_EXPORT(gethostbyname);
 
 int gethostbyname_r(const char *name, struct hostent *ret, char *buf,
                 size_t buflen, struct hostent **result, int *h_errnop)
@@ -40,6 +41,7 @@ void freeaddrinfo(struct addrinfo *ai)
 {
     lwip_freeaddrinfo(ai);
 }
+RTM_EXPORT(freeaddrinfo);
 
 int getaddrinfo(const char *nodename,
        const char *servname,
@@ -48,3 +50,4 @@ int getaddrinfo(const char *nodename,
 {
     return lwip_getaddrinfo(nodename, servname, hints, res);
 }
+RTM_EXPORT(getaddrinfo);
diff --git a/components/dfs/filesystems/lwip/lwip_select.c b/components/dfs/filesystems/lwip/lwip_select.c
index 3477b6f1d6eb594b82652c2146a7d527c1b2061f..31d9190cfceb265a8d723c7017ed6f95fc15679d 100644
--- a/components/dfs/filesystems/lwip/lwip_select.c
+++ b/components/dfs/filesystems/lwip/lwip_select.c
@@ -118,5 +118,6 @@ select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
     
     return result;
 }
+RTM_EXPORT(select);
 
 #endif
diff --git a/components/dfs/filesystems/lwip/lwip_sockets.c b/components/dfs/filesystems/lwip/lwip_sockets.c
index 346ef7b266378b84da6916855cf048a822f79fa8..6b68378f7d82ac992102b284d509b471ea3ecc9e 100644
--- a/components/dfs/filesystems/lwip/lwip_sockets.c
+++ b/components/dfs/filesystems/lwip/lwip_sockets.c
@@ -32,154 +32,167 @@
 
 int accept(int s, struct sockaddr *addr, socklen_t *addrlen)
 {
-	int new_client = -1;
+    int new_client = -1;
     int sock = dfs_lwip_getsocket(s);
 
     new_client = lwip_accept(sock, addr, addrlen);
-	if (new_client != -1)
-	{
-		/* this is a new socket, create it in file system fd */
-		int fd;
-		struct dfs_fd *d;
-		
-		/* allocate a fd */
-		fd = fd_new();
-		if (fd < 0)
-		{
-			rt_set_errno(-DFS_STATUS_ENOMEM);
-			lwip_close(sock);
-
-            printf("no fd yet!\n");
-			return -1;
-		}
-		d = fd_get(fd);
-
-		/* this is a socket fd */
-		d->type = FT_SOCKET;
-		d->path = RT_NULL;
-		
-		d->fs = dfs_lwip_get_fs();
-		
-		d->flags = DFS_O_RDWR; /* set flags as read and write */
-		d->size = 0;
-		d->pos	= 0;
-
-		/* set socket to the data of dfs_fd */
-		d->data = (void*) new_client;
-
-	    /* release the ref-count of fd */
-	    fd_put(d);
-        
+    if (new_client != -1)
+    {
+        /* this is a new socket, create it in file system fd */
+        int fd;
+        struct dfs_fd *d;
+
+        /* allocate a fd */
+        fd = fd_new();
+        if (fd < 0)
+        {
+            rt_set_errno(-DFS_STATUS_ENOMEM);
+            lwip_close(sock);
+
+            rt_kprintf("no fd yet!\n");
+            return -1;
+        }
+        d = fd_get(fd);
+
+        /* this is a socket fd */
+        d->type = FT_SOCKET;
+        d->path = RT_NULL;
+
+        d->fs = dfs_lwip_get_fs();
+
+        d->flags = DFS_O_RDWR; /* set flags as read and write */
+        d->size = 0;
+        d->pos  = 0;
+
+        /* set socket to the data of dfs_fd */
+        d->data = (void *) new_client;
+
+        /* release the ref-count of fd */
+        fd_put(d);
+
         return fd;
-	}
+    }
 
-	return new_client;
+    return new_client;
 }
+RTM_EXPORT(accept);
 
 int bind(int s, const struct sockaddr *name, socklen_t namelen)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_bind(sock, name, namelen);
 }
+RTM_EXPORT(bind);
 
 int shutdown(int s, int how)
 {
     int sock;
-	struct dfs_fd *d;
+    struct dfs_fd *d;
 
-	d = fd_get(s);
-	if (d == RT_NULL)
-	{
-		rt_set_errno(-DFS_STATUS_EBADF);
-		
-		return -1;
-	}
+    d = fd_get(s);
+    if (d == RT_NULL)
+    {
+        rt_set_errno(-DFS_STATUS_EBADF);
 
-	sock = dfs_lwip_getsocket(s);
+        return -1;
+    }
+
+    sock = dfs_lwip_getsocket(s);
     if (lwip_shutdown(sock, how) == 0)
     {
-    	/* socket has been closed, delete it from file system fd */
-		fd_put(d);
-		fd_put(d);
-		
-		return 0;
+        /* socket has been closed, delete it from file system fd */
+        fd_put(d);
+        fd_put(d);
+
+        return 0;
     }
 
-	return -1;
+    return -1;
 }
+RTM_EXPORT(shutdown);
 
-int getpeername (int s, struct sockaddr *name, socklen_t *namelen)
+int getpeername(int s, struct sockaddr *name, socklen_t *namelen)
 {
     int sock = dfs_lwip_getsocket(s);
 
     return lwip_getpeername(sock, name, namelen);
 }
+RTM_EXPORT(getpeername);
 
-int getsockname (int s, struct sockaddr *name, socklen_t *namelen)
+int getsockname(int s, struct sockaddr *name, socklen_t *namelen)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_getsockname(sock, name, namelen);
 }
+RTM_EXPORT(getsockname);
 
-int getsockopt (int s, int level, int optname, void *optval, socklen_t *optlen)
+int getsockopt(int s, int level, int optname, void *optval, socklen_t *optlen)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_getsockopt(sock, level, optname, optval, optlen);
 }
+RTM_EXPORT(getsockopt);
 
-int setsockopt (int s, int level, int optname, const void *optval, socklen_t optlen)
+int setsockopt(int s, int level, int optname, const void *optval, socklen_t optlen)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_setsockopt(sock, level, optname, optval, optlen);
 }
+RTM_EXPORT(setsockopt);
 
 int connect(int s, const struct sockaddr *name, socklen_t namelen)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_connect(sock, name, namelen);
 }
+RTM_EXPORT(connect);
 
 int listen(int s, int backlog)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_listen(sock, backlog);
 }
+RTM_EXPORT(listen);
 
 int recv(int s, void *mem, size_t len, int flags)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_recv(sock, mem, len, flags);
 }
+RTM_EXPORT(recv);
 
 int recvfrom(int s, void *mem, size_t len, int flags,
-      struct sockaddr *from, socklen_t *fromlen)
+             struct sockaddr *from, socklen_t *fromlen)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_recvfrom(sock, mem, len, flags, from, fromlen);
 }
+RTM_EXPORT(recvfrom);
 
 int send(int s, const void *dataptr, size_t size, int flags)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_send(sock, dataptr, size, flags);
 }
+RTM_EXPORT(send);
 
 int sendto(int s, const void *dataptr, size_t size, int flags,
-    const struct sockaddr *to, socklen_t tolen)
+           const struct sockaddr *to, socklen_t tolen)
 {
     int sock = dfs_lwip_getsocket(s);
-    
+
     return lwip_sendto(sock, dataptr, size, flags, to, tolen);
 }
+RTM_EXPORT(sendto);
 
 int socket(int domain, int type, int protocol)
 {
@@ -207,13 +220,13 @@ int socket(int domain, int type, int protocol)
         d->path = RT_NULL;
 
         d->fs = dfs_lwip_get_fs();
-        
+
         d->flags = DFS_O_RDWR; /* set flags as read and write */
         d->size = 0;
         d->pos  = 0;
-        
+
         /* set socket to the data of dfs_fd */
-        d->data = (void*) sock;
+        d->data = (void *) sock;
     }
 
     /* release the ref-count of fd */
@@ -221,4 +234,4 @@ int socket(int domain, int type, int protocol)
 
     return fd;
 }
-
+RTM_EXPORT(socket);
diff --git a/components/dfs/filesystems/lwip/sys/socket.h b/components/dfs/filesystems/lwip/sys/socket.h
index 5317e05e4ce61e53949feb6ebe3a17d9e32354cf..b9608d97edd5fbfaa4e21c932ea3f015574ede97 100644
--- a/components/dfs/filesystems/lwip/sys/socket.h
+++ b/components/dfs/filesystems/lwip/sys/socket.h
@@ -29,9 +29,11 @@
 extern "C" {
 #endif
 
+#include <inttypes.h>
 #include <lwip/sockets.h>
 
 typedef uint16_t sa_family_t;
+typedef uint16_t in_port_t;
 
 struct sockaddr_storage
 {