Simple TCP scan with Go

Question

I am learning to use Golang to develop hacking tools through Blackhat-Go and port scan scanme.nmap.org on Windows and Linux while doing TCP scanning.Here's my code

package main

import (
    "fmt"
    "net"
    "sort"
)

func worker(ports, result chan int) {
    for port := range ports {
        address := fmt.Sprintf("scanme.nmap.org:%d", port)
        conn, err := net.Dial("tcp", address)
        if err != nil {
            result <- 0
            continue
        }
        conn.Close()
        result <- port
    }
}

func main() {
    ports := make(chan int, 100)
    result := make(chan int)
    var openport []int

    for i := 0; i < cap(ports); i++ {
        go worker(ports, result)
    }

    go func() {
        for i := 0; i < 1024; i++ {
            ports <- i
        }
    }()

    for i := 0; i < 1024; i++ {
        port := <-result
        if port != 0 {
            openport = append(openport, port)
        }
    }

    close(ports)
    close(result)
    sort.Ints(openport)

    for _, value := range openport {
        fmt.Printf("%d open\n", value)
    }
}

Running on Windows shows that port 25 is open.

22 open
25 open 
80 open 
110 open

However, port 25 is not detected on Linux.

22 open
80 open 
110 open

I used NMAP to scan and found that the state of port 25 is Filtered.

25/tcp filtered smtp

Why is port 25 detected on Windows.

any help please.