diff --git a/book_with_bridge/ftp_server/ftp/conn.go b/book_with_bridge/ftp_server/ftp/conn.go
new file mode 100644
index 0000000..6947fea
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/conn.go
@@ -0,0 +1,62 @@
+package ftp
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"strings"
+)
+
+type Conn struct {
+	conn net.Conn
+	dataType dataType
+	dataPort *dataPort
+	rootDir string
+	workDir string
+}
+
+func NewConn(conn net.Conn, rootDir string) *Conn {
+	return &Conn{
+		conn: conn,
+		rootDir: rootDir,
+		workDir: "/",
+	}
+}
+
+func Serve (c *Conn) {
+	c.respond(status220)
+
+	s := bufio.NewScanner(c.conn)
+	for s.Scan() {
+		input := strings.Fields(s.Text())
+		if len(input) == 0 {
+			continue
+		}
+		command, args := input[0], input[1:]
+		fmt.Printf("<< %s %v", command, args)
+
+		switch command {
+		case "CWD": // cd
+			c.cwd(args)
+		case "LIST": // ls
+			c.list(args)
+		case "PORT":
+			c.port(args)
+		case "USER":
+			c.user(args)
+		case "QUIT": // close
+			c.respond(status221)
+			return
+		case "RETR": // get
+			c.retr(args)
+		case "TYPE":
+			c.setDataType(args)
+		default:
+			c.respond(status502)
+		}
+	}
+	if s.Err() != nil {
+		fmt.Print(s.Err())
+	}
+	
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/ftp/cwd.go b/book_with_bridge/ftp_server/ftp/cwd.go
new file mode 100644
index 0000000..c66093a
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/cwd.go
@@ -0,0 +1,25 @@
+package ftp
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+func (c *Conn) cwd(args []string) {
+	if len(args) != 1 {
+		c.respond(status501)
+		return
+	}
+
+	workDir := filepath.Join(c.workDir, args[0])
+	absPath := filepath.Join(c.rootDir, workDir)
+	_, err := os.Stat(absPath)
+	if err != nil {
+		fmt.Print(err)
+		c.respond(status550)
+		return
+	}
+	c.workDir = workDir
+	c.respond(status200)
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/ftp/dataconn.go b/book_with_bridge/ftp_server/ftp/dataconn.go
new file mode 100644
index 0000000..8cd781e
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/dataconn.go
@@ -0,0 +1,65 @@
+package ftp
+
+import "net"
+
+func (c *Conn) dataConnect() (net.Conn, error) {
+	conn, err := net.Dial("tcp", c.dataPort.toAddress())
+	if err != nil {
+		return nil, err
+	}
+	return conn, nil
+}
+
+ dataConn, err := c.dataConnect()
+  if err != nil {
+    log.Print(err)
+    c.respond(status425)
+    return
+  }
+  defer dataConn.Close()
+
+  for _, file := range files {
+    _, err := fmt.Fprint(dataConn, file.Name(), c.EOL())
+    if err != nil {
+      log.Print(err)
+      c.respond(status426)
+    }
+  }
+  _, err = fmt.Fprintf(dataConn, c.EOL())
+  if err != nil {
+    log.Print(err)
+    c.respond(status426)
+  }
+
+  c.respond(status226)
+
+  func (c *Conn) retr(args []string) {
+	if len(args) != 1 {
+		c.respond(status501)
+		return
+	}
+
+	path := filepath.Join(c.rootDir, c.workDir, args[0])
+	file, err := os.Open(path)
+	if err != nil {
+		log.Print(err)
+		c.respond(status550)
+	}
+	c.respond(status150)
+
+	dataConn, err := c.dataConnect()
+	if err != nil {
+		log.Print(err)
+		c.respond(status425)
+	}
+	defer dataConn.Close()
+
+	_, err = io.Copy(dataConn, file)
+	if err != nil {
+		log.Print(err)
+		c.respond(status426)
+		return
+	}
+	io.WriteString(dataConn, c.EOL())
+	c.respond(status226)
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/ftp/datatype.go b/book_with_bridge/ftp_server/ftp/datatype.go
new file mode 100644
index 0000000..a88ffa7
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/datatype.go
@@ -0,0 +1,25 @@
+package ftp
+
+type dataType int
+
+const (
+	ascii dataType = iota
+	binary
+)
+
+func (c *Conn) setDataType(args []string) {
+	if len(args) == 0 {
+		c.respond(status501)
+	}
+
+	switch args[0] {
+	case "A":
+		c.dataType = ascii
+	case "I": // image/binary
+		c.dataType = binary
+	default:
+		c.respond(status504)
+		return
+	}
+	c.respond(status200)
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/ftp/list.go b/book_with_bridge/ftp_server/ftp/list.go
new file mode 100644
index 0000000..072b7a8
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/list.go
@@ -0,0 +1,47 @@
+package ftp
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+)
+
+func (c *Conn) list(args []string) {
+	var target string
+	if len(args) > 0 {
+		target = filepath.Join(c.rootDir, c.workDir, args[0])
+	} else {
+		target = filepath.Join(c.rootDir, c.workDir)
+	}
+
+	files, err := ioutil.ReadDir(target)
+	if err != nil {
+		fmt.Print(err)
+		c.respond(status550)
+		return
+	}
+	c.respond(status150)
+
+	dataConn, err := c.dataConnect()
+	if err != nil {
+		fmt.Print(err)
+		c.respond(status425)
+		return
+	}
+	defer dataConn.Close()
+
+	for _, file := range files {
+		_, err := fmt.Fprint(dataConn, file.Name(), c.EOL())
+		if err != nil {
+			fmt.Print(err)
+			c.respond(status426)
+		}
+	}
+	_, err = fmt.Fprintf(dataConn, c.EOL())
+	if err != nil {
+		fmt.Print(err)
+		c.respond(status426)
+	}
+
+	c.respond(status226)
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/ftp/port.go b/book_with_bridge/ftp_server/ftp/port.go
new file mode 100644
index 0000000..9dc291c
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/port.go
@@ -0,0 +1,42 @@
+package ftp
+
+import "fmt"
+
+func (c *Conn) port(args []string) {
+	if len(args) != 1 {
+		c.respond(status501)
+		return
+	}
+	dataPort, err := dataPortFromHostPort(args[0])
+	if err != nil {
+		fmt.Print(err)
+		c.respond(status501)
+		return
+	}
+	c.dataPort = dataPort
+	c.respond(status200)
+}
+
+type dataPort struct {
+	h1, h2, h3, h4 int // host
+	p1, p2         int // port
+}
+
+func dataPortFromHostPort(hostPort string) (*dataPort, error) {
+	var dp dataPort
+	_, err := fmt.Sscanf(hostPort, "%d,%d,%d,%d,%d,%d",
+		&dp.h1, &dp.h2, &dp.h3, &dp.h4, &dp.p1, &dp.p2)
+	if err != nil {
+		return nil, err
+	}
+	return &dp, nil
+}
+
+func (d *dataPort) toAddress() string {
+	if d == nil {
+		return ""
+	}
+	// convert hex port bytes to decimal port
+	port := d.p1<<8 + d.p2
+	return fmt.Sprintf("%d.%d.%d.%d:%d", d.h1, d.h2, d.h3, d.h4, port)
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/ftp/respond.go b/book_with_bridge/ftp_server/ftp/respond.go
new file mode 100644
index 0000000..3b4f72a
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/respond.go
@@ -0,0 +1,40 @@
+package ftp
+
+import "fmt"
+
+const (
+	status150 = "150 File status okay; about to open data connection."
+	status200 = "200 Command okay."
+	status220 = "220 Service ready for new user."
+	status221 = "221 Service closing control connection."
+	status226 = "226 Closing data connection. Requested file action successful."
+	status230 = "230 User %s logged in, proceed."
+	status425 = "425 Can't open data connection."
+	status426 = "426 Connection closed; transfer aborted."
+	status501 = "501 Syntax error in parameters or arguments."
+	status502 = "502 Command not implemented."
+	status504 = "504 Cammand not implemented for that parameter."
+	status550 = "550 Requested action not taken. File unavailable."
+)
+
+// respond copies a string to the client and terminates it with the appropriate FTP line terminator
+// for the datatype.
+func (c *Conn) respond(s string) {
+	fmt.Print(">> ", s)
+	_, err := fmt.Fprint(c.conn, s, c.EOL())
+	if err != nil {
+		fmt.Print(err)
+	}
+}
+
+// EOL returns the line terminator matching the FTP standard for the datatype.
+func (c *Conn) EOL() string {
+	switch c.dataType {
+	case ascii:
+		return "\r\n"
+	case binary:
+		return "\n"
+	default:
+		return "\n"
+	}
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/ftp/user.go b/book_with_bridge/ftp_server/ftp/user.go
new file mode 100644
index 0000000..861c8f6
--- /dev/null
+++ b/book_with_bridge/ftp_server/ftp/user.go
@@ -0,0 +1,10 @@
+package ftp
+
+import (
+	"fmt"
+	"strings"
+)
+
+func (c *Conn) user(args []string) {
+	c.respond(fmt.Sprintf(status230, strings.Join(args, " ")))
+}
\ No newline at end of file
diff --git a/book_with_bridge/ftp_server/go.mod b/book_with_bridge/ftp_server/go.mod
new file mode 100644
index 0000000..1da823a
--- /dev/null
+++ b/book_with_bridge/ftp_server/go.mod
@@ -0,0 +1,3 @@
+module main
+
+go 1.24.5
diff --git a/book_with_bridge/ftp_server/main.go b/book_with_bridge/ftp_server/main.go
new file mode 100644
index 0000000..cd7ffd4
--- /dev/null
+++ b/book_with_bridge/ftp_server/main.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"path/filepath"
+	"main/ftp"
+)
+
+var port int
+var rootDir string
+
+func init() {
+	flag.IntVar(&port,"port",9090,"port to listet")
+	flag.StringVar(&rootDir,"rootDir","public","root Directory")
+	flag.Parse()
+}
+
+func handleConn(conn net.Conn) {
+	defer conn.Close()
+
+	absPath, err := filepath.Abs(rootDir)
+	if err != nil {
+		fmt.Print(err)
+	}
+	ftp.Serve(ftp.NewConn(conn,absPath))
+}
+
+func main() {
+	server := fmt.Sprintf(":%d",port)
+	listener,err := net.Listen("tcp",server)
+	if err != nil {
+		log.Fatal(err)
+	}
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			fmt.Print(err)
+			continue
+		}
+		handleConn(conn)
+	}
+}