The **udhcpd enable** command is used to start a dhcp server on a
specific network interface.

@static
@category udhcpd
@param {object} options The dhcp server configuration.
@param {function} callback The callback function.
@returns {process} The child process.
@example

var udhcpd = require('wireless-tools/udhcpd');

var options = {
interface: 'wlan0',
start: '192.168.10.100',
end: '192.168.10.200',
option: {
router: '192.168.10.1',
subnet: '255.255.255.0',
dns: [ '4.4.4.4', '8.8.8.8' ]
}
};

udhcpd.enable(options, function(err) {
// the dhcp server was started
});
function enable(options, callback) {
  var file = options.interface + '-udhcpd.conf';

  var commands = [].concat(
    'cat <<EOF >' + file + ' && udhcpd ' + file + ' && rm -f ' + file,
    expand(options));

  return this.exec(commands.join('\n'), callback);
}