FtpServer Listeners

Listeners are the component in FtpServer which is responsible for listening on the network socket and when clients connect create the user session, execute commands and so on. An FtpServer can have multiple listeners at the same time, some examples include:

one listener on port 21 (the default option)
one cleartext listener on port 21 and one for implicit SSL on port 22
one cleartext listener in an internal IP address only and one for implicit SSL for the external IP address

Listeners are identified by a name, the default listener is identified by "default".

The main network configuration is performed on the listeners, for example the port to listen on and SSL configuration.

Configuration

config
- listeners
  - <listener name>
    - class (org.apache.ftpserver.listener.mina.MinaListener)
    - address (<none>)
    - port (21)
    - implicit-ssl (false)
    - ssl
    - data-connection
      - class (<none>)
      - idle-time (10)
      - active
        
        enable (true)
        
        local-address (<none>)
        
        local-port (0)
        
        ip-check (false)
      - passive
        
        address (<none>)
        
        ports (0)
      - ssl

Configuration Parameter	Description
config.listeners.<listener name>.class	The listener class org.apache.ftpserver.listener.mina.MinaListener : High performance listener using asyncronous IO. Requires Java 5 org.apache.ftpserver.listener.io.IOListener : Listener using blocking IO. Requires Java 1.4
config.listeners.<listener name>.address	FTP server address the listener will bind to
config.listeners.<listener name>.port	FTP server port
config.listeners.<listener name>.implicit-ssl	True if the listener should use implicit SSL
config.listeners.<listener name>.ssl	See TLS/SSL configuration
Data connection configuration
config.listeners.<listener name>.data-connection.class	Required, no default value, normally set to "org.apache.ftpserver.DefaultDataConnectionConfig"
config.listeners.<listener name>.data-connection.idle-time	Maximum data connection idle time in second. 0 means no limit. The default value is 10.
config.listeners.<listener name>.data-connection.active.enable	PORT data connection enabled. The default value is true.
config.listeners.<listener name>.data-connection.active.local-address	The localhost address used when local port specified in active data transfer.
config.listeners.<listener name>.data-connection.active.local-port	The local port to be used during active data transfer. According to the specifications, it should be 20. The default value is 0. It means that any free port will be used.
config.listeners.<listener name>.data-connection.active.ip-check	Check the PORT IP with the client IP. The default value is false.
config.listeners.<listener name>.data-connection.passive.address	FTP passive (PASV) address The default value is localhost.
config.listeners.<listener name>.data-connection.passive.ports	See FtpServer Configure passive ports
config.listeners.<listener name>.data-connection.ssl	See TLS/SSL configuration

Examples

Change the listener port

config.listeners.default.port=2021

One internal and one external listener

config.listeners.internal.address=192.168.10.12
config.listeners.external.address=245.12.15.18

Use the blocking IO listener

config.listeners.default.class=org.apache.ftpserver.listener.io.IOListener

Supporting SSL

config.listeners.default.ssl.class=org.apache.ftpserver.ssl.DefaultSsl
config.listeners.default.ssl.keystore-file=mykeystore.jks
config.listeners.default.ssl.keystore-password=secret
config.listeners.default.ssl.key-password=secret

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