Use ident to get username of incoming connection

webserver-ident-username.go

// Example in Go of using the ident protocol to extract the username of the connecting user.
// The idea is to use this on corporate networks to identify users logged in to a Windows
// RDP machine by their ActiveDirectory username.

// NOTE: For Windows, this is a good ident server https://sourceforge.net/projects/retinascan/
// that supports multiple users and all that good stuff.

http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

		parts := strings.SplitN(r.RemoteAddr, ":", 2)
		// whatever, just my test for a specific machine - may need to do something slightly different for ipv6, since that contains colons
		if parts[0] == "192.168.27.4" {
			port := parts[1]

			conn, err := net.Dial("tcp", parts[0]+":113")
			if err != nil {
				panic(err)
			}
			// cmd := fmt.Sprintf("80, %s", port)
			cmd := fmt.Sprintf("%s, 9000", port) // FIXME: should look at actual server port number
			log.Printf("SENDING IDENT COMMAND: %s\n", cmd)
			fmt.Fprintf(conn, "%s\r\n", cmd)
			result, err := bufio.NewReader(conn).ReadString('\n')
			log.Printf("Identd result: %s\n", result)
			resultParts := strings.Split(result, ":")
			if len(resultParts) > 3 && strings.TrimSpace(resultParts[1]) == "USERID" {
				userName := strings.TrimSpace(resultParts[3])
				log.Printf("USERNAME: %s\n", userName)
			} else {
				log.Printf("Unknown result\n")
			}
		}

}