diff --git a/core/bbs.js b/core/bbs.js
index a0256d3e..aff1bdb3 100644
--- a/core/bbs.js
+++ b/core/bbs.js
@@ -73,6 +73,9 @@ function main() {
             },
             function initConfig(configPath, configPathSupplied, callback) {
                 const configFile = configPath + 'config.hjson';
+                conf.Config.create(configFile, {}, err => {
+                    console.log(err);
+                });
                 conf.init(resolvePath(configFile), function configInit(err) {
 
                     //
diff --git a/core/config.js b/core/config.js
index 1910fef0..d352a568 100644
--- a/core/config.js
+++ b/core/config.js
@@ -22,8 +22,28 @@ class Config extends ConfigLoader {
     }
 
     static create(basePath, options, cb) {
-        options.mergeCustomizer = (objValue, srcValue, key, object, source, stack) => {
-            console.log(key);
+        const replacePaths = [
+            'loginServers.ssh.algorithms.kex',
+            'loginServers.ssh.algorithms.cipher',
+            'loginServers.ssh.algorithms.hmac',
+            'loginServers.ssh.algorithms.compress',
+        ];
+        const replaceKeys = [
+            'args', 'sendArgs', 'recvArgs', 'recvArgsNonBatch',
+        ];
+
+        options.defaultConfig = DefaultConfig();
+
+        options.defaultsCustomizer = (defaultVal, configVal, key, path) => {
+            if (Array.isArray(defaultVal) && Array.isArray(configVal)) {
+                if (replacePaths.includes(path) || replaceKeys.includes(key)) {
+                    //  full replacement using user config value
+                    return configVal;
+                } else {
+                    //  merge user config & default config; keep only unique
+                    _.uniq(defaultVal.concat(configVal));
+                }
+            }
         };
 
         return ConfigLoader.create(basePath, options, cb);
diff --git a/core/config_loader.js b/core/config_loader.js
new file mode 100644
index 00000000..a4b76649
--- /dev/null
+++ b/core/config_loader.js
@@ -0,0 +1,235 @@
+//  deps
+const paths = require('path');
+const async = require('async');
+
+const _ = require('lodash');
+const reduceDeep = require('deepdash/getReduceDeep')(_);
+
+module.exports = class ConfigLoader {
+    constructor(options) {
+        this.current = {};
+        this.hotReload = _.get(options, 'hotReload', true);
+    }
+
+    static create(basePath, options, cb) {
+        const config = new ConfigLoader(options);
+        config._init(
+            basePath,
+            options,
+            err => {
+                return cb(err, config);
+            }
+        );
+    }
+
+    get() {
+        return this.current;
+    }
+
+    _convertTo(value, type) {
+        switch (type) {
+            case 'bool' :
+            case 'boolean' :
+                value = 'true' === value.toLowerCase();
+                break;
+
+            case 'number' :
+                {
+                    const num = parseInt(value);
+                    if (!isNaN(num)) {
+                        value = num;
+                    }
+                }
+                break;
+
+            case 'object' :
+                try {
+                    value = JSON.parse(value);
+                } catch(e) { }
+                break;
+
+            case 'date' :
+            case 'time' :
+            case 'datetime' :
+            case 'timestamp' :
+                {
+                    const m = moment(value);
+                    if (m.isValid()) {
+                        value = m;
+                    }
+                }
+                break;
+
+            case 'regex' :
+                //	:TODO: What flags to use, etc.?
+                break;
+        }
+
+        return value;
+    }
+
+    _resolveEnvironmentVariable(spec) {
+        const [prefix, varName, type, array] = spec.split(':');
+        if (!varName) {
+            return;
+        }
+
+        let value = process.env[varName];
+        if (!value) {
+            return;
+        }
+
+        if ('array' === array) {
+            value = value.split(',').map(v => this._convertTo(v, type));
+        } else {
+            value = this._convertTo(value, type);
+        }
+
+        return value;
+    }
+
+    _loadConfigFile(filePath, cb) {
+        const ConfigCache = require('./config_cache');
+
+        const options = {
+            filePath,
+            hotReload   : this.hotReload,
+            callback    : this._configFileChanged.bind(this),
+        };
+
+        ConfigCache.getConfigWithOptions(options, (err, config) => {
+            return cb(err, config);
+        });
+    }
+
+    _configFileChanged({fileName, fileRoot}) {
+        const reCachedPath = paths.join(fileRoot, fileName);
+        ConfigCache.getConfig(reCachedPath, (err, config) => {
+            /*
+            if(!err) {
+                mergeValidateAndFinalize(config, err => {
+                    if(!err) {
+                        const Events = require('./events.js');
+                        Events.emit(Events.getSystemEvents().ConfigChanged);
+                    }
+                });
+            } else {
+                console.stdout(`Configuration ${reCachedPath} is invalid: ${err.message}`); //  eslint-disable-line no-console
+            }
+            */
+        });
+    }
+
+    _init(basePath, options, cb) {
+        options.defaultConfig = options.defaultConfig || {};
+
+        //
+        //  1 - Fetch base configuration from |basePath|
+        //  2 - Merge with |defaultConfig|, if any
+        //  3 - Resolve any includes
+        //  4 - Resolve @reference and @environment
+        //  5 - Perform any validation
+        //
+        async.waterfall(
+            [
+                (callback) => {
+                    return this._loadConfigFile(basePath, callback);
+                },
+                (config, callback) => {
+                    if (_.isFunction(options.defaultsCustomizer)) {
+                        const stack = [];
+                        const mergedConfig = _.mergeWith(
+                            options.defaultConfig,
+                            config,
+                            (defaultVal, configVal, key, target, source) => {
+                                var path;
+                                while (true) {
+                                    if (!stack.length) {
+                                        stack.push({source, path : []});
+                                    }
+
+                                    const prev = stack[stack.length - 1];
+                                    if (source === prev.source) {
+                                        path = prev.path.concat(key);
+                                        stack.push({source : configVal, path});
+                                        break;
+                                    }
+                                    stack.pop();
+                                }
+                                path = path.join('.');
+                                return options.defaultsCustomizer(defaultVal, configVal, key, path);
+                            }
+                        );
+                        return callback(null, mergedConfig);
+                    } else {
+                        //  :TODO: correct?
+                        _.defaultsDeep(config, options.defaultConfig);
+                        return callback(null, config);
+                    }
+                },
+                (config, callback) => {
+                    const configRoot = paths.dirname(basePath);
+                    return this._resolveIncludes(configRoot, config, callback);
+                },
+                (config, callback) => {
+                    config = this._resolveAtSpecs(config);
+                    return callback(null, config);
+                },
+            ],
+            (err, config) => {
+                if (!err) {
+                    this.current = config;
+                }
+                return cb(err);
+            }
+        );
+    }
+
+    _resolveIncludes(configRoot, config, cb) {
+        if (!Array.isArray(config.includes)) {
+            return cb(null, config);
+        }
+
+        //  If a included file is changed, we need to re-cache, so this
+        //  must be tracked...
+        const includePaths = config.includes.map(inc => paths.join(configRoot, inc));
+        async.eachSeries(includePaths, (includePath, nextIncludePath) => {
+            this._loadConfigFile(includePath, (err, includedConfig) => {
+                if (err) {
+                    return nextIncludePath(err);
+                }
+
+                _.defaultsDeep(config, includedConfig);
+                return nextIncludePath(null);
+            });
+        },
+        err => {
+            return cb(err, config);
+        });
+    }
+
+    _resolveAtSpecs(config) {
+        //  :TODO: mapValuesDeep may be better here
+        return reduceDeep(
+            config,
+            (acc, value, key, parent, ctx) => {
+                //	resolve self references; there may be a better way...
+                if (_.isString(value) && '@' === value.charAt(0)) {
+                    if (value.startsWith('@reference:')) {
+                        value = value.slice(11);
+                        const ref = _.get(acc, value);
+                        if (ref) {
+                            _.set(acc, ctx.path, ref);
+                        }
+                    } else if (value.startsWith('@environment:')) {
+                        value = this._resolveEnvironmentVariable(value);
+                        if (!_.isUndefined(value)) {
+                            _.set(acc, ctx.path, value);
+                        }
+                    }
+                }
+                return acc;
+            }
+        );
+    }
+};