VFS Utils FTPServer Configuration

To use this bridge you should just add the VFS libraries, the VFS Utils FTPServer library, the VFS Utils Utils library and, if needed, your custom VFS Provider and its dependencies to the common/lib directory of your Apache Mina FTP Server installation.

The configuration of the FTPServer is based on a Spring configuration.

As explained in the introduction there are two ways to use the VFS bridge; you can use VFS based authentication or not. The configuration needed for both ways are detailed below.

VFS based authentication

Below you can see an example of a configuration.

  <?xml version="1.0" encoding="UTF-8"?>
  <server xmlns="http://mina.apache.org/ftpserver/spring/v1"
           http://mina.apache.org/ftpserver/spring/v1 http://mina.apache.org/ftpserver/ftpserver-1.0.xsd        
        <!-- VFS user manager configuration -->
                <beans:bean class="org.vfsutils.ftpserver.usermanager.VfsUserManager"> 
                        <beans:property name="vfsHomePath" value="/home/${user}"/>
                        <beans:property name="authenticator.vfsRoot" value="file:///d:/ftproot"/>
                        <beans:property name="authenticator.vfsType" value="virtual"/>
                        <!-- beans:property name="authenticator.vfsDomain" value="mydomain" -->
                        <beans:property name="authenticator.vfsShare" value="true"/>
                        <beans:property name="authenticator.factory.share" value="false"/>
                        <beans:property name="adminName" value="admin"/>
                        <beans:property name="anonymousName" value="anonymous"/>
                        <beans:property name="anonymousPwd" value="anon@localhost"/>
                        <!-- normal user settings -->
                        <beans:property name="writePermission" value="false"/>
                        <beans:property name="maxLogin" value="10"/>
                        <beans:property name="maxLoginPerIp" value="5"/>
                        <beans:property name="maxIdleTime" value="3600"/>
                        <beans:property name="uploadRate" value="2000"/>
                        <beans:property name="downloadRate" value="2000"/>
                        <!-- admin settings -->
                        <beans:property name="admin.writePermission" value="false"/>
        <!-- VFS based file system manager configuration -->
                <beans:bean class="org.vfsutils.ftpserver.filesystem.VfsFileSystemFactory"/>            

To have your VFS Provider handle authentication you should set the FTPServer user manager to the VFS user manager. You must set the root of the VFS, the type, the home directory of the user and optionally the domain to be used for authentication. The relation between the root of the VFS and the type is explained in Dctm VFS Provider configuration. Other FTP related settings such as the maximum logins per user, read-only access or throughput constraints can be configured too.

If the user name is specified within the VFS root this user name will replace the user name specified by the user in his credentials. The same yields for his password. Therefore normally you would not specify those in your VFS root.

Within the file system specified by the root you can set the path to the users home directory in which the user will start after connecting. The specification of the users home directory can contain the variable $user which will be replaced by the name of the user.

Since VFS supports the notion of domain, but this is not supported by FTP you can optionally specify the domain that should be used in the authentication.

Properties authenticator.vfsShare and authenticator.factory.share are discussed below.

You can set which user should be regarded as the admin account with adminName. This account has special privileges such as the 'site who' and the 'site stat' commands. The FTP User management functions do not work however.

To enable anonymous access you can specify which username should be used towards the file system for anonymous access. Though not very safe you can also specify which password is used for that account. By default anonymous is used for the name and anon@localhost is used for the password.

Opposite to the default User Managers of the FTP Server which allow different settings for each user, the VFS User Manager only makes an exception for the administrator role. Below the settings are described for the normal users, to change the settings for the admin account you should put admin before the setting, e.g. admin.writePermission or admin.msaxLogin. Note that the settings spanning all users are set in the connection manager.

Write permission can be configured using writePermission; by setting this to false the users will have read-only access to the underlying file system (the default value is true).

The maximum number of simultaneous logins by the user can be set, as well as the maximum per IP (maxLogin and maxLoginPerIp). The default values are 1 and 1, allowing only one connection per user account. When 0 is put, no restrictions are applied. Note that when you use Windows Explorer as FTP client, at least 2 connections are needed.

The connection does not expire by default, but this can be configured setting the maximum idle time in seconds (maxIdleTime), when 0 is put, the connection does not expire.

Upload and download rates can be limited by setting uploadRate and downloadRate (in bytes). When 0 is put there are no restrictions.

This will project the directory d:/ftproot as the file system accessible via FTP and will start in home/userA when 'userA' logs in.

To mount a ZIP file you could set

 <beans:property name="authenticator.vfsRoot" value="zip://d:/ftproot.zip"/>
 <beans:property name="authenticator.vfsType" value="normal"/>


 <beans:property name="authenticator.vfsRoot" value="file://d:/ftproot.zip"/>
 <beans:property name="authenticator.vfsType" value="layered"/>

FTP session isolation / reuse of the file system

By default ftp sessions with the same user/password combination share a FileSystem instance, becaue FileSystemManager.resolveFile(String, FileSystemOptions) will return the same FileSystem if the FileSystemOptions are the same.

You might want to isolate FTP sessions of the same user, for instance to have single-threaded access to your file system.

Two configuration options influence this. The most radical is to create a new FileSystemManager for each session.

 <beans:property name="authenticator.factory.share" value="false"/>

This provides the highest grade of isolation. Creating the default file system manager is quite fast. You can specify your own manager if you prefer.

 <beans:property name="authenticator.factory.managerClassName" value="my.own.Manager"/>

You can also opt to share the FileSystemManager, but not the FileSystem.

 <beans:property name="authenticator.vfsShare" value="false"/>

This will isolate operations on the file system done in different sessions, resulting in single threaded access to the file system.

It will take more memory then sharing the file system, but has the advantage that the file system can be properly closed when the ftp session is terminated.

When you share both the manager as the file system then the filesystem will not be closed when the FTP session is terminated because this would affect the other sessions. Instead the method FileSystemManager.freeUnusedResources() is called, but this will not remove the FileSystem from the internal administration of the FileSystemManager (the FileSystemProvider to be precise).

Note: it does not make much sense to not share the file system if the manager is not shared either.

Standard user authentication

Another way of working with the VFS bridge is to let the Apache FTPServer do the authentication. In that case you can choose between the available database or file based user authentication or write your own mechanism.

You can specify the root to the VFS in the home directory of each user in your user administration. In this way each user can have a completely different mapping. In this case the configuration would look like this:

        <!-- VFS based file system manager configuration -->
                <beans:bean class="org.vfsutils.ftpserver.filesystem.VfsFileSystemFactory"/>            

However, in most cases you will want to also specify the VFS root in the FileSystemManager and use the homedirectory in the user administration as a relative path within that root.

Here you have the same options as when using the VFS User Manager; you can specify the root and type.

An example configuration is this:

        <!-- VFS based file system manager configuration -->
                <beans:bean class="org.vfsutils.ftpserver.filesystem.VfsFileSystemFactory">
                        <beans:property name="authenticator.vfsRoot" value="file:///d:/ftproot"/>
                        <beans:property name="authenticator.vfsType" value="virtual"/>