Apache Commons Net

Apache Commons Net™ library implements the client side of many basic Internet protocols. The purpose of the library is to provide fundamental protocol access, not higher-level abstractions. Therefore, some of the design violates object-oriented design principles. Our philosophy is to make the global functionality of a protocol accessible (e.g., TFTP send file and receive file) when possible, but also provide access to the fundamental protocols where applicable so that the programmer may construct his own custom implementations (e.g, the TFTP packet classes and the TFTP packet send and receive methods are exposed).

Features

Supported protocols include:

  • FTP/FTPS
  • FTP over HTTP (experimental)
  • NNTP
  • SMTP(S)
  • POP3(S)
  • IMAP(S)
  • Telnet
  • TFTP
  • Finger
  • Whois
  • rexec/rcmd/rlogin
  • Time (rdate) and Daytime
  • Echo
  • Discard
  • NTP/SNTP

Background

Apache Jakarta Commons Net started as a commercial Java library called NetComponents, originally developed by ORO, Inc. in the early days of Java. After its 1.3.8 release in 1998, the source code was donated to the Apache Software Foundation and made available under the Apache License. Since then, many programmers have contributed to the continued development of Jakarta Commons Net. The current version numbering scheme bears no relation to the old. In other words, Jakarta Commons Net 1.0 succeeded and supplanted NetComponents 1.3.8. Apache Jakarta Commons is now an independent project and is called Apache Commons.

Examples

Commons NET includes several working sample applications that you can use. Source files are included in the source (and binary) archives, and a compiled jar is provided.

To use one of the sample applications, ensure that the example and main jars are both in the same directory. Then run the class as per the following example:
java -jar [path/]commons-net-examples-3.1.jar FTPClientExample [parameters]
This uses the helper application which supports shorthand class names.
Alternatively, ensure that the example and main jars are on the classpath. Then invoke the class directly, for example:
java -cp commons-net-examples-3.1.jar;commons-net-3.1.jar examples/ftp/FTPClientExample [parameters]

FTP (package: examples/ftp)

  • FTPClientExample demonstrates file download and upload, LIST, MLST etc over FTP(S) and FTP over HTTP
  • ServerToServerFTP This program arranges a server to server file transfer that transfers a file from host1 to host2.
  • TFTPExample This is an example of a simple Java tftp client

MAIL (package: examples/mail)

  • IMAPMail This is an example program demonstrating how to use the IMAP[S]Client class.
  • POP3Mail This is an example program demonstrating how to use the POP3[S]Client class.
  • SMTPMail This is an example program demonstrating how to use the SMTP[S]Client class.

NNTP (package: examples/nntp)

  • ArticleReader Simple class showing one way to read an article header and body.
  • ExtendedNNTPOps Simple class showing some of the extended commands (AUTH, XOVER, LIST ACTIVE)
  • ListNewsgroups This is a simple example using the NNTP package to approximate the Unix newsgroups command. It connects to the specified news server and issues fetches the list of newsgroups stored by the server. On servers that store a lot of newsgroups, this command can take a very long time (listing upwards of 30,000 groups).
  • MessageThreading Sample program demonstrating the use of article iteration and threading.
  • PostMessage This is an example program using the NNTP package to post an article to the specified newsgroup(s). It prompts you for header information and a filename to post.

NTP (package: examples/ntp)

  • NTPClient This is an example program demonstrating how to use the NTPUDPClient class. This program sends a Datagram client request packet to a Network time Protocol (NTP) service port on a specified server, retrieves the time, and prints it to standard output along with the fields from the NTP message header (e.g. stratum level, reference id, poll interval, root delay, mode, ...)
  • TimeClient This is an example program demonstrating how to use the TimeTCPClient and TimeUDPClient classes. This program connects to the default time service port of a specified server, retrieves the time, and prints it to standard output.

TELNET (package: examples/telnet)

  • TelnetClientExample This is a simple example of use of TelnetClient.
  • WeatherTelnet This is an example of a trivial use of the TelnetClient class. It connects to the weather server at the University of Michigan, um-weather.sprl.umich.edu port 3000, and allows the user to interact with the server via standard input.

Unix utilities (package: examples/unix)

  • chargen This is a simple example of use of chargen.
  • daytime This is a simple example of use of daytime.
  • echo This is a simple example of use of echo.
  • finger This is a simple example of use of finger.
  • fwhois This is a simple example of use of fwhois.
  • rdate This is a simple example of use of rdate.
  • rexec This is a simple example of use of rexec.
  • rlogin This is a simple example of use of rlogin.
  • rshell This is a simple example of use of rshell.

Further Information

For more info, see the JavaDoc, or look at some of the following articles: