APEx Application Protocol Explorer

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What is APEx?

If you teach or learn about networking, you have probably used a Telnet client to fake a client using another protocol such as HTTP. APEx does this and much more:

APEx is a tool for exploring Internet application protocols such as HTTP, FTP, SMPT, and POP3.
APEx provides a client or server that displays incoming messages and lets you respond interactively.

APEx Structure

APEx consists of three applications, each with a simple graphical user interface:

An interactive TCP Client that you can use to send requests to servers on any port number anywhere on the Internet.
An interactive TCP Server that you can use to listen for requests on any port number and handle multiple clients.
A Control Panel for starting any of the other components.

APEx Features

APEx is written entirely in Java, so that it can run almost anywhere. It requires the JRE 1.3 or later.
A display of client and server addresses and port numbers reinforces the concept of the TCP connection.
Opening and closing of TCP connections is under user control.
The message display uses color to distinguish between sent or received messages.
Messages can be typed and displayed in either ASCII or hexadecimal.
Carriage returns and line feeds in outgoing messages are under the user's control.
The font size is adjustable in each application.

Downloading and Running APEx

Note: This is version Beta5.2. The server bug in 5.2 has been fixed.

APEx is available free from http://www.cs.dal.ca/~grundke/cgi-bin/APEx/download.cgi as a zip file, containing, among other things, the Java jar file APEx.jar. If the Java interpreter is on your path, give a command such as

    java -cp APEx.jar APEx

to launch the Control Panel, otherwise (for Windows) use something like

    c:\jdk1.3.1\bin\java -cp APEx.jar APEx

Command-line Parameters

Individual components of APEx can also be started from the command line or from a script using commands like

    java -cp APEx.jar APExTcpClient
    java -cp APEx.jar APExTcpServer

followed by parameters detailed in the usage text below.

Client

Usage:  APExTcpClient [-h<host>] -p<port> [-f<fontsize>] -[b|B] [-o[<file>]]
where   <host>:  Host name or IP address of server;  default localhost
        <port>:  Server port number (decimal)
        <font>:  GUI font size in points (decimal, range 8..72)
        b or B:  Bold font (good for lecture demos)
        <file>:  File name for std output (default: clientOut<port>.txt

Server

Usage:  APExTcpServer -p<port> [-f<fontsize>] -[b|B] [-o[<file>]
where   <port>:  Server port number (decimal)
        <font>:  GUI font size in points (decimal, range 8..72);  default 12
        b or B:  Bold font (good for lecture demos)
        <file>:  File name for std output (default: serverOut<port>.txt

Legalities

This software is good for nothing in particular. Use at your own risk. The author isn't liable for anything.