mTCP DHCP Client
2013-04-26 Version
Michael Brutman (mbbrutman@gmail.com)


Introduction

  A DHCP client is a small utility that helps you automatically configure
  the networking parameters for a machine, allowing it to use your
  network.  This is an alternative to "static" addressing where you set
  the network parameters for your machine manually.

  Most home networks have a router that has a DHCP server built in,
  making DHCP the preferred way to configure a machine for networking.
  This DHCP client can be used to automatically configure the networking
  parameters for all of the mTCP applications and with some cleverness
  it can be used for other networking stacks as well.


Hardware requirements

  8088 processor or better
  85KB available RAM
  CGA, Monochrome (MDA), EGA or VGA display
  Supported Ethernet card


Software requirements

  DOS 2.1 or newer
  Packet driver for your Ethernet adapter


Setup instructions

  DHCP is built using the mTCP library.  The detailed setup instructions
  for mTCP can be found in SETUP.TXT.

  Here is the quick story:

  Step 1: Load your packet driver.  If your packet driver loads correctly
          it will probably report the MAC address of your Ethernet
          hardware.

  Step 2: Create a configuration file for mTCP.  The configuration file
          is a text file that all mTCP apps will read when they start.
          The smallest possible configuration file has one line in it
          to tell mTCP where the packet driver is loaded.  Here is an
          example:

            packetint 0x60

          Just replace the 0x60 with whatever software interrupt your
          packet driver is set to use.  There are more things you can
          add to the configuration file but this will get you started.

  Step 3: Set the MTCPCFG environment variable to the full path and name
          of the configuration file.  For example:

            set MTCPCFG=c:\mtcp\tcp.cfg

          And now you should be ready to run DHCP.  (See the section below.)


Using DHCP

  Usage is like this:

    dhcp [options]

  Options are:

    -help           Show a help message
    -retries <n>    Retry n times before giving up (default=3)
    -timeout <n>    Set timeout for each attempt to n seconds (default=10)
    -packetstats    Show packet statistics at the end


  When DHCP runs it will send a series of UDP packets and try to
  negotiate a DHCP lease with a DHCP server on your network.  If DHCP
  is successful it will set a return code of 0, show the network
  settings it received on the screen, and write the new network settings
  to the mTCP configuration file.

  If DHCP fails it will set a return code of 1.

  You can check the return code in a batch file using ERRORLEVEL.
  Here is a simple example:

    ne2000 0x60 3
    set mtcpcfg=e:\mtcp\tcp.cfg
    dhcp -retries 3 -timeout 20
    echo off
    if errorlevel 1 goto Errmsg
    echo DHCP worked
    goto End
    :Errmsg
    echo DHCP failed!
    :End


  You should run this program at least once a day, and before running
  any other mTCP programs.  This program will write the settings it
  gets into a configuration file that the other mTCP programs will
  look for and use.  (You do not need to run DHCP before each mTCP
  application.)


DHCP failures

  DHCP is often the first thing that runs after a user does the
  basic mTCP configuration.  As a result it is often the first thing
  to fail.  The most common form of failure is a timeout.  Below
  are some factors that can cause timeouts:

    - a misconfigured card
    - using the wrong packet driver
    - bad parameters to the packet driver
    - cabling/network issues

  A detailed discussion of these factors can be found in
  the DEBUG.TXT file.

  In the unlikely event that you can not use DHCP you can still
  use mTCP applications; you will have to do the network parameter
  setup manually though.  See the SETUP.TXT file for details.
  I have not yet met a DHCP server that mTCP does not work with
  so being forced to do a manual setup is unlikely.


Support

  Have a comment or need help?  Please email me at mbbrutman@gmail.com.


More information: http://www.brutman.com/mTCP

Created May 20th, 2011, Last updated April 26th, 2013
(C)opyright Michael B. Brutman, mbbrutman@gmail.com

