Add maxjitter flag to hyp client

This to allow configurable time between knock sequence transmissions.  It's important the sequence arrive in the correct order, and some networks have multiple paths.

hyp/cmd/knock.go

@@ -38,6 +38,14 @@ Example usage:
 			panic(fmt.Errorf("failed to parse command flag 'secret': %w", err))
 		}
 
+		maxJitter, err := cmd.Flags().GetInt("maxjitter")
+		if err != nil {
+			panic(fmt.Errorf("failed to parse command flag 'maxjitter': %w", err))
+		}
+		if maxJitter < 1 || maxJitter > 1500 {
+			panic(fmt.Errorf("maxjitter must be value between 1 and 1500"))
+		}
+
 		secretBytes, err := os.ReadFile(secretFilePath)
 		if err != nil {
 			log.Fatalf("failed to read file 'hyp.secret': %v", err)
@@ -50,12 +58,12 @@ Example usage:
 		}
 
 		// Transmit
-		fmt.Println("Transmitting knock sequence:", ports)
 		for _, port := range ports {
+			fmt.Printf("knock | %s:%d\n", args[0], port)
 			conn, _ := net.Dial("udp", fmt.Sprintf("%s:%d", args[0], port))
 			conn.Write([]byte{0})
 			conn.Close()
-			time.Sleep(time.Millisecond * 200) // TBD: Make this configurable with flag (maxJitter)
+			time.Sleep(time.Millisecond * time.Duration(maxJitter)) // TBD: Make this configurable with flag (maxJitter)
 		}
 	},
 }
@@ -64,4 +72,5 @@ func init() {
 	rootCmd.AddCommand(knockCmd)
 
 	knockCmd.PersistentFlags().String("secret", "hyp.secret", "Path to the file containing the hyp secret.")
+	knockCmd.PersistentFlags().Int("maxjitter", 200, "Specifies the time in milliseconds between knock sequence transmissions.")
 }