package main

import (
        "fmt"
        "log"
        "net"
        "net/http"
)

const xff = true

func index(w http.ResponseWriter, r *http.Request) {
        var ip string
        if r.URL.Path != "/" {
        	return
        }
        if xff {
                ip = r.Header.Get("X-Forwarded-For")
        } else {
                ip, _, _ = net.SplitHostPort(r.RemoteAddr)
        }
        fmt.Fprintln(w, ip)
}

func main() {
        http.HandleFunc("/", index)
        log.Fatal(http.ListenAndServe(":7004", nil))
}