Java.lang.SecurityManager.checkConnect() Method

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Description

The java.lang.SecurityManager.checkConnect(String host, int port) method throws a SecurityException if the calling thread is not allowed to open a socket connection to the specified host and port number. A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.

This method calls checkPermission with the SocketPermission(host+":"+port,"connect") permission if the port is not equal to -1. If the port is equal to -1, then it calls checkPermission with the SocketPermission(host,"resolve") permission. If you override this method, then you should make a call to super.checkConnect at the point the overridden method would normally throw an exception.

Declaration

Following is the declaration for java.lang.SecurityManager.checkConnect() method

public void checkConnect(String host, int port)

Parameters

• host − the host name port to connect to.

• port − the protocol port to connect to.

Return Value

This method does not return a value.

Exception

• SecurityException − if the calling thread does not have permission to open a socket connection to the specified host and port.

• NullPointerException − if the host argument is null.

Example

Our examples require that the permissions for each command is blocked. A new policy file was set that allows only the creating and setting of our Security Manager. The file is in C:/java.policy and contains the following text −

grant {
   permission java.lang.RuntimePermission "setSecurityManager";
   permission java.lang.RuntimePermission "createSecurityManager";
   permission java.lang.RuntimePermission "usePolicy";
};

The following example shows the usage of lang.SecurityManager.checkConnect() method.

package com.tutorialspoint;

public class SecurityManagerDemo {

   public static void main(String[] args) {

      // set the policy file as the system securuty policy
      System.setProperty("java.security.policy", "file:/C:/java.policy");

      // create a security manager
      SecurityManager sm = new SecurityManager();

      // set the system security manager
      System.setSecurityManager(sm);

      // perform the check
      sm.checkConnect("www.tutorialspoint.com", 8080);

      // print a message if we passed the check
      System.out.println("Allowed!");
   }
}

Let us compile and run the above program, this will produce the following result −

Exception in thread "main" java.security.AccessControlException: access denied (java.net.SocketPermission www.tutorialspoint.com:8080 connect,resolve)