[GH-ISSUE #4766] frp似乎会代替TCP服务端回复[FIN ACK]？

gitea-mirror commented

2026-05-05 14:24:47 -06:00

Owner

Originally created by @Curtion on GitHub (Apr 24, 2025).
Original GitHub issue: https://github.com/fatedier/frp/issues/4766

Bug Description

frp在收到客户端FIN后会好像直接回复[FIN ACK], 从而导致后续数据包服务端无法正常发送给客户端。这里给出一个客户端和服务端的示例代码，如果在本地连接则正常，如果通过FRP转发则异常

frpc Version

0.62.0

frps Version

0.62.0

System Architecture

frps:linux/amd64; frpc:windows/amd64

Configurations

服务端代码:

package main

import (
	"fmt"
	"net"
)

func main() {
	listener, err := net.Listen("tcp", "127.0.0.1:21000")
	if err != nil {
		fmt.Println("Error listening:", err.Error())
		return
	}
	defer listener.Close()
	fmt.Println("Server listening on :21000")

	for {
		conn, err := listener.Accept()
		if err != nil {
			fmt.Println("Error accepting:", err.Error())
			continue
		}
		go handleRequest(conn)
	}
}

func handleRequest(conn net.Conn) {
	defer conn.Close()

	buf := make([]byte, 1024)
	n, err := conn.Read(buf)
	if err != nil {
		fmt.Println("Error reading:", err.Error())
		return
	}

	data := string(buf[:n])
	fmt.Printf("Received from client: %s\n", data)

	_, err = conn.Write([]byte("Server received: " + data))
	if err != nil {
		fmt.Println("Error writing:", err.Error())
	}
}

客户端代码:

package main

import (
	"fmt"
	"net"
)

func main() {
	// conn, err := net.Dial("tcp", "127.0.0.1:21000")
	conn, err := net.Dial("tcp", "server:21666")
	if err != nil {
		fmt.Println("Error connecting:", err.Error())
		return
	}
	defer conn.Close()

	message := "hello"
	_, err = conn.Write([]byte(message))
	if err != nil {
		fmt.Println("Error sending:", err.Error())
		return
	}

	// Close write side to signal we're done sending
	tcpConn := conn.(*net.TCPConn)
	tcpConn.CloseWrite()

	buf := make([]byte, 1024)
	n, err := conn.Read(buf)
	if err != nil {
		fmt.Println("Error receiving:", err.Error())
		return
	}

	fmt.Printf("Server response: %s\n", string(buf[:n]))
}

Logs

Steps to reproduce

TCP客户端在发送数据后立即关闭写入, 例如:

	tcpConn := conn.(*net.TCPConn)
	tcpConn.CloseWrite()

Affected area

Docs
Installation
Performance and Scalability
Security
User Experience
Test and Release
Developer Infrastructure
Client Plugin
Server Plugin
Extensions
Others

Originally created by @Curtion on GitHub (Apr 24, 2025). Original GitHub issue: https://github.com/fatedier/frp/issues/4766 ### Bug Description frp在收到客户端FIN后会好像直接回复[FIN ACK], 从而导致后续数据包服务端无法正常发送给客户端。这里给出一个客户端和服务端的示例代码，如果在本地连接则正常，如果通过FRP转发则异常 ### frpc Version 0.62.0 ### frps Version 0.62.0 ### System Architecture frps:linux/amd64; frpc:windows/amd64 ### Configurations 服务端代码: ```go package main import ( "fmt" "net" ) func main() { listener, err := net.Listen("tcp", "127.0.0.1:21000") if err != nil { fmt.Println("Error listening:", err.Error()) return } defer listener.Close() fmt.Println("Server listening on :21000") for { conn, err := listener.Accept() if err != nil { fmt.Println("Error accepting:", err.Error()) continue } go handleRequest(conn) } } func handleRequest(conn net.Conn) { defer conn.Close() buf := make([]byte, 1024) n, err := conn.Read(buf) if err != nil { fmt.Println("Error reading:", err.Error()) return } data := string(buf[:n]) fmt.Printf("Received from client: %s\n", data) _, err = conn.Write([]byte("Server received: " + data)) if err != nil { fmt.Println("Error writing:", err.Error()) } } ``` 客户端代码: ```go package main import ( "fmt" "net" ) func main() { // conn, err := net.Dial("tcp", "127.0.0.1:21000") conn, err := net.Dial("tcp", "server:21666") if err != nil { fmt.Println("Error connecting:", err.Error()) return } defer conn.Close() message := "hello" _, err = conn.Write([]byte(message)) if err != nil { fmt.Println("Error sending:", err.Error()) return } // Close write side to signal we're done sending tcpConn := conn.(*net.TCPConn) tcpConn.CloseWrite() buf := make([]byte, 1024) n, err := conn.Read(buf) if err != nil { fmt.Println("Error receiving:", err.Error()) return } fmt.Printf("Server response: %s\n", string(buf[:n])) } ``` ### Logs ![Image](https://github.com/user-attachments/assets/18b9fea8-c9d3-4256-812c-c9809330b5a9) ![Image](https://github.com/user-attachments/assets/f2330849-6287-49d1-9651-bbd0c17a0762) ![Image](https://github.com/user-attachments/assets/82dde0b6-8028-4f66-a243-9afefd51c351) ### Steps to reproduce TCP客户端在发送数据后立即关闭写入, 例如: ```go tcpConn := conn.(*net.TCPConn) tcpConn.CloseWrite() ``` ### Affected area - [ ] Docs - [ ] Installation - [ ] Performance and Scalability - [ ] Security - [ ] User Experience - [ ] Test and Release - [ ] Developer Infrastructure - [ ] Client Plugin - [ ] Server Plugin - [ ] Extensions - [x] Others

gitea-mirror

2026-05-05 14:24:47 -06:00

closed this issue
added the
lifecycle/stale
label

gitea-mirror commented

2026-05-05 14:24:51 -06:00

Author

Owner

@xqzr commented on GitHub (Apr 25, 2025):

frp 会终结 TCP

@xqzr commented on GitHub (Apr 25, 2025): frp 会终结 TCP

gitea-mirror commented

2026-05-05 14:24:51 -06:00

Author

Owner

@github-actions[bot] commented on GitHub (May 10, 2025):

Issues go stale after 14d of inactivity. Stale issues rot after an additional 3d of inactivity and eventually close.

@github-actions[bot] commented on GitHub (May 10, 2025): Issues go stale after 14d of inactivity. Stale issues rot after an additional 3d of inactivity and eventually close.