diff --git a/.gitignore b/.gitignore
index ab68491..d01d092 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 *.o
 *.a
 *.pcap
+*.so
 build/*
 test/unit/unit
 tags
diff --git a/Makefile b/Makefile
index 1043176..8d824d0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,39 +1,62 @@
 CC?=gcc
 CFLAGS:=-Wall -Werror -Wextra -I.
+CFLAGS+=-g -ggdb
+LDFLAGS+=-pthread
+
 OBJ=build/femtotcp.o \
-	build/test/test_linux_eventloop.o build/port/posix/linux_tap.o
+	build/port/posix/linux_tap.o
 
-all: build/test-evloop
+EXE=build/tcpecho build/test-evloop
+LIB=libfemtotcp.so
 
 
+all: $(EXE) $(LIB)
+
 #Static library
 static: CFLAGS+=-static
 static: libtcpip.a
 
+
+
 libtcpip.a: $(OBJ)
 	@ar rcs $@ $^
 
+libfemtotcp.so:CFLAGS+=-fPIC
+libfemtotcp.so:  build/pie/port/posix/bsd_socket.o build/pie/femtotcp.o \
+	build/pie/port/posix/linux_tap.o
+	@mkdir -p `dirname $@` || true
+	@echo "[LD] $@"
+	@$(CC) $(CFLAGS) $(LDFLAGS) -shared -o $@ -Wl,--start-group $(^) -Wl,--end-group
+
+
 clean:
 	@rm -rf build
 	@make -C src/test/unit clean
 
-# Test
-asan: build/test-evloop
+asan: $(EXE) $(LIB)
 asan:CFLAGS+=-fsanitize=address
 asan:LDFLAGS+=-static-libasan
-build/test:CFLAGS+=-g -ggdb -DTEST_MAIN -DETHERNET
-build/test:LDFLAGS+=-pthread
 
 
-build/test-evloop: $(OBJ)
+# Test
+build/test-evloop: $(OBJ) build/test/test_linux_eventloop.o
 	@echo "[LD] $@"
-	@$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(OBJ)
+	@$(CC) $(CFLAGS) $(LDFLAGS) -o $@ -Wl,--start-group $(^) -Wl,--end-group
+
+build/tcpecho: $(OBJ) build/port/posix/bsd_socket.o build/test/tcp_echo.o
+	@echo "[LD] $@"
+	@$(CC) $(CFLAGS) $(LDFLAGS) -o $@ -Wl,--start-group $(^) -Wl,--end-group
 
 build/%.o: src/%.c
 	@mkdir -p `dirname $@` || true
 	@echo "[CC] $<"
 	@$(CC) $(CFLAGS) -c $< -o $@
 
+build/pie/%.o: src/%.c
+	@mkdir -p `dirname $@` || true
+	@echo "[CC] $<"
+	@$(CC) $(CFLAGS) -c $< -o $@
+
 unit:
 	@make -C src/test/unit
 	@mkdir -p build/test/
diff --git a/config.h b/config.h
index 36bfcf3..78924f5 100644
--- a/config.h
+++ b/config.h
@@ -11,4 +11,8 @@
 
 #define MAX_NEIGHBORS 16
 
+/* Linux test configuration */
+#define FEMTOTCP_IP "10.10.10.2"
+#define LINUX_IP "10.10.10.1"
+
 #endif
diff --git a/femtotcp.h b/femtotcp.h
index 01f4686..9395ecc 100644
--- a/femtotcp.h
+++ b/femtotcp.h
@@ -12,6 +12,7 @@ typedef uint32_t ip4;
 #define ee32(x) __builtin_bswap32(x)
 #define DEBUG
 
+
 #ifdef DEBUG
 #include <stdio.h>
 #define LOG(fmt, ...) printf(fmt, ##__VA_ARGS__)
@@ -39,9 +40,15 @@ struct ipconf {
 };
 
 /* Socket interface */
+#define MARK_TCP_SOCKET 0x1000 /* Mark a socket as TCP */
+#define MARK_UDP_SOCKET 0x4000 /* Mark a socket as UDP */
+
+
 #ifndef FEMTO_POSIX
 #define IPSTACK_SOCK_STREAM 1
 #define IPSTACK_SOCK_DGRAM 2
+
+
 struct ipstack_sockaddr_in {
     uint16_t sin_family;
     uint16_t sin_port;
@@ -96,6 +103,8 @@ ip4 atoip4(const char *ip);
 #define CB_EVENT_TIMEOUT 0x08  /* Timeout */
 void ipstack_register_callback(struct ipstack *s, int sock_fd, void (*cb)(int sock_fd, uint16_t events, void *arg), void *arg);
 
+/* External requirements */
+uint32_t ipstack_getrandom(void);
 
 
 
diff --git a/src/femtotcp.c b/src/femtotcp.c
index 98e769b..6bc34b9 100644
--- a/src/femtotcp.c
+++ b/src/femtotcp.c
@@ -14,8 +14,6 @@
 #define MAX_TIMERS MAX_TCPSOCKETS * 3
 
 /* Constants */
-#define MARK_TCP_SOCKET 0x1000 /* Mark a socket as TCP */
-#define MARK_UDP_SOCKET 0x4000 /* Mark a socket as UDP */
 
 #define IPPROTO_ICMP 0x01
 #define IPPROTO_TCP 0x06
diff --git a/src/port/posix/bsd_socket.c b/src/port/posix/bsd_socket.c
index e0e2079..4386cfb 100644
--- a/src/port/posix/bsd_socket.c
+++ b/src/port/posix/bsd_socket.c
@@ -1,11 +1,39 @@
 /* POSIX socket calls wrapper for femtoTCP */
 
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
 #include <netinet/in.h>
+#include <stdarg.h>
+#include <pthread.h>
+#include <errno.h>
+#include <dlfcn.h>
+#include <sys/time.h>
 #define FEMTO_POSIX
+#include "config.h"
 #include "femtotcp.h"
 
-static __thread int in_the_stack = 0;
-static __thread struct ipstack IPSTACK;
+static __thread int in_the_stack = 1;
+static struct ipstack *IPSTACK = NULL;
+
+/* host_ functions are the original functions from the libc */
+static int (*host_socket  ) (int domain, int type, int protocol) = NULL;
+static int (*host_bind    ) (int sockfd, const struct sockaddr *addr, socklen_t addrlen);
+static int (*host_connect ) (int sockfd, const struct sockaddr *addr, socklen_t addrlen);
+static int (*host_accept  ) (int sockfd, struct sockaddr *addr, socklen_t *addrlen);
+static int (*host_listen  ) (int sockfd, int backlog);
+static ssize_t (*host_recvfrom) (int sockfd, void *buf, size_t len, int flags, struct sockaddr *addr, socklen_t *addrlen);
+static ssize_t (*host_recv    ) (int sockfd, void *buf, size_t len, int flags);
+static ssize_t (*host_read    ) (int sockfd, void *buf, size_t len);
+static ssize_t (*host_sendto  ) (int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *addr, socklen_t addrlen);
+static ssize_t (*host_send    ) (int sockfd, const void *buf, size_t len, int flags);
+static ssize_t (*host_write   ) (int sockfd, const void *buf, size_t len);
+static int (*host_close   ) (int sockfd);
+static int (*host_setsockopt) (int sockfd, int level, int optname, const void *optval, socklen_t optlen);
+static int (*host_getsockopt) (int sockfd, int level, int optname, void *optval, socklen_t *optlen);
+static int (*host_getsockname) (int sockfd, struct sockaddr *addr, socklen_t *addrlen);
+static int (*host_getpeername) (int sockfd, struct sockaddr *addr, socklen_t *addrlen);
+
 
 #define swap_socketcall(call, name) \
 { \
@@ -13,51 +41,192 @@ static __thread struct ipstack IPSTACK;
     if (host_##call == NULL) { \
         *(void **)(&host_##call) = dlsym(RTLD_NEXT, name); \
         if ((msg = dlerror()) != NULL) \
-        fprintf (stderr, "%s: dlsym(%s): %s\n", "picotcp", name, msg); \
+        fprintf (stderr, "%s: dlsym(%s): %s\n", "femtoTCP", name, msg); \
     } \
 }
 
 
 #define conditional_steal_call(call, fd, ...) \
     if(in_the_stack) { \
-        return host_##call(i, ## __VA_ARGS__); \
+        return host_##call(fd, ## __VA_ARGS__); \
     } else { \
-        if (get_femto_fd(i) > -1) { \
-            int __femto_retval = ft_posix_##call(&IPSTACK, fd, ## __VA_ARGS__); \
+        if ((fd & (MARK_TCP_SOCKET | MARK_UDP_SOCKET)) != 0) { \
+            int __femto_retval = ft_##call(IPSTACK, fd, ## __VA_ARGS__); \
             if (__femto_retval < 0) { \
                 errno = __femto_retval; \
                 return -1; \
             } \
             return __femto_retval; \
         }else { \
-            return host_##call(i, ## __VA_ARGS__); \
+            return host_##call(fd, ## __VA_ARGS__); \
         } \
     }
 
-/* Generator for a wrapper function intercepting the return value
- * '-11' (EAGAIN). It keeps blocking until the underlying femtoTCP
- * stack is ready to process the call.
- */
-#define GEN_SOCKET_CALL(call) \
-int ft_posix_##call(struct ipstack *ipstack, int fd, ...) { \
-    int ret; \
-    va_list args; \
-    va_start(args, fd); \
-    do { \
-        ret = call(fd, args); \
-        if (ret == -11) { \
-            pthread_yield(); \
+#define conditional_steal_blocking_call(call, fd, ...) \
+    if(in_the_stack) { \
+        return host_##call(fd, ## __VA_ARGS__); \
+    } else { \
+        if ((fd & (MARK_TCP_SOCKET | MARK_UDP_SOCKET)) != 0) { \
+            int __femto_retval; \
+            do { \
+                __femto_retval = ft_##call(IPSTACK, fd, ## __VA_ARGS__); \
+                if (__femto_retval == -11) { \
+                    usleep(1000); \
+                } \
+            } while (__femto_retval == -11); \
+            if (__femto_retval < 0) { \
+                errno = __femto_retval; \
+                return -1; \
+            } \
+            return __femto_retval; \
+        }else { \
+            return host_##call(fd, ## __VA_ARGS__); \
         } \
-    } while (ret == -11); \
-    va_end(args); \
-    return ret; \
+    }
+
+
+int ft_setsockopt(struct ipstack *ipstack, int fd, int level, int optname, const void *optval, socklen_t optlen) {
+    (void)ipstack;
+    (void)fd;
+    (void)level;
+    (void)optname;
+    (void)optval;
+    (void)optlen;
+    return 0;
+}
+
+int ft_getsockopt(struct ipstack *ipstack, int fd, int level, int optname, void *optval, socklen_t *optlen) {
+    (void)ipstack;
+    (void)fd;
+    (void)level;
+    (void)optname;
+    (void)optval;
+    (void)optlen;
+    return 0;
+}
+
+int socket(int domain, int type, int protocol) {
+    if (in_the_stack) {
+        return host_socket(domain, type, protocol);
+    } else {
+        return ft_socket(IPSTACK, domain, type, protocol);
+    }
+}
+
+int listen(int sockfd, int backlog) {
+    conditional_steal_call(listen, sockfd, backlog);
+}
+
+int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen) {
+    conditional_steal_call(bind, sockfd, addr, addrlen);
+}
+
+int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen) {
+    conditional_steal_call(getsockopt, sockfd, level, optname, optval, optlen);
+}
+
+int getpeername(int sockfd, struct sockaddr *addr, socklen_t *addrlen) {
+    conditional_steal_call(getpeername, sockfd, addr, addrlen);
+}
+
+int getsockname(int sockfd, struct sockaddr *addr, socklen_t *addrlen) {
+    conditional_steal_call(getsockname, sockfd, addr, addrlen);
+}
+
+int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen) {
+    conditional_steal_call(setsockopt, sockfd, level, optname, optval, optlen);
+}
+
+int close(int sockfd) {
+    conditional_steal_call(close, sockfd);
+}
+
+/* Blocking calls */
+int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen) {
+    conditional_steal_blocking_call(accept, sockfd, addr, addrlen);
+}
+
+int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen) {
+    conditional_steal_blocking_call(connect, sockfd, addr, addrlen);
+}
+
+ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags, struct sockaddr *addr, socklen_t *addrlen) {
+    conditional_steal_blocking_call(recvfrom, sockfd, buf, len, flags, addr, addrlen);
+}
+
+ssize_t recv(int sockfd, void *buf, size_t len, int flags) {
+    conditional_steal_blocking_call(recv, sockfd, buf, len, flags);
+}
+
+ssize_t read(int sockfd, void *buf, size_t len) {
+    conditional_steal_blocking_call(read, sockfd, buf, len);
+}
+
+ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *addr, socklen_t addrlen) {
+    conditional_steal_blocking_call(sendto, sockfd, buf, len, flags, addr, addrlen);
+}
+
+ssize_t send(int sockfd, const void *buf, size_t len, int flags) {
+    conditional_steal_blocking_call(send, sockfd, buf, len, flags);
+}
+
+ssize_t write(int sockfd, const void *buf, size_t len) {
+    conditional_steal_blocking_call(write, sockfd, buf, len);
 }
 
 
-GEN_SOCKET_CALL(acccept)
-GEN_SOCKET_CALL(bind)
-GEN_SOCKET_CALL(close)
-GEN_SOCKET_CALL(connect)
-GEN_SOCKET_CALL(sendto)
-GEN_SOCKET_CALL(recvfrom)
+
+/* Catch-all function to initialize a new tap device as the network interface.
+ * This is defined in port/linux.c
+ * */
+extern int tap_init(struct ll *dev, const char *name, uint32_t host_ip);
+
+void *ft_posix_ip_loop(void *arg) {
+    struct ipstack *ipstack = (struct ipstack *)arg;
+    uint32_t ms_next;
+    struct timeval tv;
+    while (1) {
+        gettimeofday(&tv, NULL);
+        ms_next = ipstack_poll(ipstack, tv.tv_sec * 1000 + tv.tv_usec / 1000);
+        usleep(ms_next * 1000);
+        in_the_stack = 1;
+    }
+    return NULL;
+}
+
+void __attribute__((constructor)) init_femto_posix() {
+    struct in_addr linux_ip; 
+    struct ll *tapdev;
+    pthread_t ipstack_thread;
+    if (IPSTACK)
+        return;
+    inet_aton(LINUX_IP, &linux_ip);
+    swap_socketcall(socket, "socket");
+    swap_socketcall(bind, "bind");
+    swap_socketcall(listen, "listen");
+    swap_socketcall(accept, "accept");
+    swap_socketcall(connect, "connect");
+    swap_socketcall(sendto, "sendto");
+    swap_socketcall(recvfrom, "recvfrom");
+    swap_socketcall(recv, "recv");
+    swap_socketcall(send, "send");
+    swap_socketcall(close, "close");
+    swap_socketcall(write, "write");
+    swap_socketcall(read, "read");
+    swap_socketcall(getsockname, "getsockname");
+    swap_socketcall(getpeername, "getpeername");
+    swap_socketcall(setsockopt, "getaddrinfo");
+    swap_socketcall(getsockopt, "freeaddrinfo");
+    ipstack_init_static(&IPSTACK);
+    tapdev = ipstack_getdev(IPSTACK);
+    if (tap_init(tapdev, "femt0", linux_ip.s_addr) < 0) {
+        perror("tap init");
+    }
+    ipstack_ipconfig_set(IPSTACK, atoip4(FEMTOTCP_IP), atoip4("255.255.255.0"),
+            atoip4(LINUX_IP));
+    printf("IP: manually configured - %s\n", FEMTOTCP_IP);
+    sleep(1);
+    pthread_create(&ipstack_thread, NULL, ft_posix_ip_loop, IPSTACK);
+    in_the_stack = 0;
+}
 
diff --git a/src/test/tcp_echo.c b/src/test/tcp_echo.c
new file mode 100644
index 0000000..9e32517
--- /dev/null
+++ b/src/test/tcp_echo.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+
+#define PORT 8
+#define BUFFER_SIZE 1024
+
+int main() {
+    int server_fd, client_fd;
+    struct sockaddr_in address;
+    int addrlen = sizeof(address);
+    char buffer[BUFFER_SIZE];
+
+    // Create a socket
+    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
+        perror("Socket failed");
+        exit(EXIT_FAILURE);
+    }
+    printf("Socket created: %d\n", server_fd);
+
+    // Bind to the specified port
+    address.sin_family = AF_INET;
+    address.sin_addr.s_addr = INADDR_ANY;
+    address.sin_port = htons(PORT);
+
+    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
+        perror("Bind failed");
+        close(server_fd);
+        exit(EXIT_FAILURE);
+    }
+    printf("Bind successful\n");
+
+    // Start listening for incoming connections
+    if (listen(server_fd, 3) < 0) {
+        perror("Listen failed");
+        close(server_fd);
+        exit(EXIT_FAILURE);
+    }
+
+
+    printf("Echo server listening on port %d\n", PORT);
+
+    while (1) {
+        // Accept a client connection
+        if ((client_fd = accept(server_fd, (struct sockaddr *)&address, (socklen_t *)&addrlen)) < 0) {
+            perror("Accept failed");
+            continue;
+        }
+
+        printf("Client connected, fd: %d\n", client_fd);
+
+        ssize_t bytes_read;
+        while ((bytes_read = read(client_fd, buffer, BUFFER_SIZE)) > 0) {
+            write(client_fd, buffer, bytes_read); // Echo data back to the client
+        }
+
+        printf("Client disconnected\n");
+        close(client_fd);
+    }
+
+    close(server_fd);
+    return 0;
+}
diff --git a/src/test/test_linux_eventloop.c b/src/test/test_linux_eventloop.c
index 7b6c7c9..dd4923e 100644
--- a/src/test/test_linux_eventloop.c
+++ b/src/test/test_linux_eventloop.c
@@ -3,15 +3,14 @@
 #include <arpa/inet.h>
 #include <pthread.h>
 #include <stdlib.h>
-#include "femtotcp.h"
 #include <sys/time.h>
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
+#include "config.h"
+#include "femtotcp.h"
 
 //#define DHCP
-#define FEMTOTCP_IP "10.10.10.2"
-#define LINUX_IP "10.10.10.1"
 #define TEST_SIZE (8 * 1024)
 
 #define BUFFER_SIZE TEST_SIZE