# Customizing the Network Server's security policy

The Network Server's Basic security policy is documented in the section Basic Network Server security policy. Most likely, you will want to customize your own security policy. For example, you might want to restrict the server's liberal file i/o permissions which let the server backup to and restore from any location in the local file system. Customizing the security policy is simple:

- A template policy lives in the Derby distribution at demo/templates/server.policy. Copy the file from this location to your own file, say myCustomized.policy. All of the following edits take place in your custom file.
- Replace the ${derby.install.url} variable with the location of the Derby jars in your local file system.
- Replace the ${derby.system.home} variable with the location of your Derby system directory. Alternatively, rather than replacing this variable, you can simply set the value of the derby.system.home system property when you boot the server.
- You may want to restrict the socket permission for `derbynet.jar`, which by default accepts connections from any host (`"*"`). Note that the special wildcard address `"0.0.0.0"` is not understood by SocketPermission, even though Derby accepts this wildcard as a valid value for accepting connections on all network interfaces (IPv4).
- Refine the file permissions needed by backup/restore, import/export, and the loading of application jars.

The following example is a copy of a sample, customized policy file:

    grant codeBase "file:/usr/local/share/sw/derby/lib/derby.jar"
    {
    //
    // These permissions are needed for everyday, embedded Derby usage.
    //
      permission java.lang.RuntimePermission "createClassLoader";
      permission java.util.PropertyPermission "derby.*", "read";
      // The next two properties are used to determine if the VM is 32 or 64 bit.
      permission java.util.PropertyPermission "sun.arch.data.model", "read";
      permission java.util.PropertyPermission "os.arch", "read";
      permission java.util.PropertyPermission "user.dir", "read";
      permission java.io.FilePermission "/usr/local/shoppingCartApp/databases","read";
      permission java.io.FilePermission "/usr/local/shoppingCartApp/databases/-",
          "read,write,delete";
      permission java.util.PropertyPermission "derby.storage.jvmInstanceId",
          "write";

    //
    // This permission lets a DBA reload the policy file while the server
    // is still running. The policy file is reloaded by invoking the
    // SYSCS_UTIL.SYSCS_RELOAD_SECURITY_POLICY() system procedure.
    //
      permission java.security.SecurityPermission "getPolicy";

    //
    // This permission lets you backup and restore databases
    // to and from a selected branch of the local file system:
    //
      permission java.io.FilePermission "/usr/local/shoppingCartApp/backups/-", "read,write,delete";
    //
    // This permission lets you import data from
    // a selected branch of the local file system:
    //
      permission java.io.FilePermission "/usr/local/shoppingCartApp/imports/-", "read";
    //
    // This permission lets you export data to
    // a selected branch of the local file system:
    //
      permission java.io.FilePermission "/usr/local/shoppingCartApp/exports/-", "write";
    //
    // This permission lets you load your databases with jar files of
    // application code
    //
      permission java.io.FilePermission "/usr/local/shoppingCartApp/lib/*", "read";
    };

    grant codeBase "file:/usr/local/share/sw/derby/lib/derbynet.jar"
    {
    //
    // This permission lets the Network Server manage connections from clients
    // originating from the localhost, on any port.
    //
      permission java.net.SocketPermission "localhost:0-", "accept";
    };

After customizing the Basic policy, you may bring up the Network Server as follows:

    java -Djava.security.manager -Djava.security.policy=/usr/local/shoppingCartApp/lib/myCustomized.policy org.apache.derby.drda.NetworkServerControl start -h localhost

Parent topic: Running the Network Server under the security manager
Related tasks
Basic Network Server security policy
Running the Network Server without a security policy