You have configured the following rules. What is the effect? sudo iptables -A INPUT -p tcp --dport 25 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT sudo iptables -A OUTPUT -p tcp --sport 25 -m conntrack --ctstate ESTABLISHED -j ACCEPT

Allow Simple Mail Transfer Protocol (SMTP) traffic. Since SSH is on TCP port 22, these rules will have no effect on SSH.

Explanation:

Allow Simple Mail Transfer Protocol (SMTP) traffic.

Inbound and outbound SMTP connections on TCP port 25, which is SMTP's default port, would not be prevented by these rules.

These rules use the Accept action to ensure that Simple Mail Transfer Protocol (SMTP) and Secure Shell (SSH) are not blocked.

Since SSH is on TCP port 22, these rules will therefore have no effect on SSH.

import java.util.Scanner;

public class Main

{

public static void main(String[] args) {

              //print the header

              System.out.println("");

              System.out.println("*                                    *");

              System.out.println("*                                    *");

              System.out.println("*   Gas-N-Clean Service Station      *");

              System.out.println("*                                    *");

              System.out.println("*   March 2, 2004                    *");

              System.out.println("*                                    *");

              System.out.println("");

               //set the constant values for gasoline

               final double REGULAR_GASOLINE = 2.89;

               final double PLUS_GASOLINE = 3.09;

               final double SUPER_GASOLINE = 3.39;

              // initialize the variables as 0

              double gasolinePrice = 0, gasolineCost = 0, carWashCost = 0, totalCost = 0;

               Scanner input = new Scanner(System.in);

               //ask the user to enter the gallons, gas type and car wash choice

               System.out.print("Enter number of gallons ");

               double gasolinePurchase = input.nextDouble();

               System.out.print("Enter gas type (R, P, S, or N) ");

               char gasType = input.next().charAt(0);

               System.out.print("Enter Y or N for car wash ");

               char carWashChoice = input.next().charAt(0);

               //check the gas type. Depending on the choice set the gasolinePrice from the corresponding constantvalue

              if(gasType == 'R')

                  gasolinePrice = REGULAR_GASOLINE;

              else if(gasType == 'P')

                  gasolinePrice = PLUS_GASOLINE;

              else if(gasType == 'S')

                  gasolinePrice = SUPER_GASOLINE;

                //calculate the gasolineCost

                gasolineCost = gasolinePurchase * gasolinePrice;

               //check the carWashChoice. If it is yes and gasolineCost is greater than 10, set the carWashCost as 1.25. Otherwise, set the carWashCost as 3.00

               if(carWashChoice == 'Y'){    

                   if(gasolineCost >= 10)

                       carWashCost = 1.25;

                   else

                       carWashCost = 3.00;

               }

              //calculate the total cost, add gasolineCost and carWashCost

              totalCost = gasolineCost + carWashCost;

               //print the values in required format

              System.out.println("Amount Gasoline purchases " + gasolinePurchase);

              System.out.println("Gallons Price per gallons $ " + gasolinePrice);

              System.out.printf("Total gasoline cost $ %.2f\n", gasolineCost);

              System.out.println("Car wash cost $ " + carWashCost);

              System.out.printf("Total due $ %.2f\n", totalCost);

               System.out.println("Thank you for stopping\nPlease come again \nRemember to buckle up and drive safely");

}  

}

Explanation:

*The code is in Java.

Please see the comments in the code for explanation