diff --git a/lib/nexpose/ajax.rb b/lib/nexpose/ajax.rb
index 655a0aab..b63d2a7c 100644
--- a/lib/nexpose/ajax.rb
+++ b/lib/nexpose/ajax.rb
@@ -1,7 +1,5 @@
 # encoding: utf-8
-
 module Nexpose
-
   # Accessor to the Nexpose AJAX API.
   # These core methods should allow direct access to underlying controllers
   # in order to test functionality that is not currently exposed
@@ -10,6 +8,8 @@ module Nexpose
   module AJAX
     module_function
 
+    # Content type strings acceptect by Nexpose.
+    #
     module CONTENT_TYPE
       XML = 'text/xml; charset=UTF-8'
       JSON = 'application/json; charset-utf-8'
@@ -28,7 +28,7 @@ def get(nsc, uri, content_type = CONTENT_TYPE::XML, options = {})
       parameterize_uri(uri, options)
       get = Net::HTTP::Get.new(uri)
       get.set_content_type(content_type)
-      _request(nsc, get)
+      request(nsc, get)
     end
 
     # PUT call to a Nexpose controller.
@@ -43,7 +43,7 @@ def put(nsc, uri, payload = nil, content_type = CONTENT_TYPE::XML)
       put = Net::HTTP::Put.new(uri)
       put.set_content_type(content_type)
       put.body = payload.to_s if payload
-      _request(nsc, put)
+      request(nsc, put)
     end
 
     # POST call to a Nexpose controller.
@@ -52,13 +52,14 @@ def put(nsc, uri, payload = nil, content_type = CONTENT_TYPE::XML)
     # @param [String] uri Controller address relative to https://host:port
     # @param [String|REXML::Document] payload XML document required by the call.
     # @param [String] content_type Content type to use when issuing the POST.
+    # @param [Fixnum] timeout Set an explicit timeout for the HTTP request.
     # @return [String|REXML::Document|Hash] The response from the call.
     #
-    def post(nsc, uri, payload = nil, content_type = CONTENT_TYPE::XML)
+    def post(nsc, uri, payload = nil, content_type = CONTENT_TYPE::XML, timeout = nil)
       post = Net::HTTP::Post.new(uri)
       post.set_content_type(content_type)
       post.body = payload.to_s if payload
-      _request(nsc, post)
+      request(nsc, post, timeout)
     end
 
     # PATCH call to a Nexpose controller.
@@ -73,7 +74,7 @@ def patch(nsc, uri, payload = nil, content_type = CONTENT_TYPE::XML)
       patch = Net::HTTP::Patch.new(uri)
       patch.set_content_type(content_type)
       patch.body = payload.to_s if payload
-      _request(nsc, patch)
+      request(nsc, patch)
     end
 
     # POST call to a Nexpose controller that uses a form-post model.
@@ -90,7 +91,7 @@ def form_post(nsc, uri, parameters, content_type = CONTENT_TYPE::FORM)
       post = Net::HTTP::Post.new(uri)
       post.set_content_type(content_type)
       post.set_form_data(parameters)
-      _request(nsc, post)
+      request(nsc, post)
     end
 
     # DELETE call to a Nexpose controller.
@@ -101,9 +102,16 @@ def form_post(nsc, uri, parameters, content_type = CONTENT_TYPE::FORM)
     def delete(nsc, uri, content_type = CONTENT_TYPE::XML)
       delete = Net::HTTP::Delete.new(uri)
       delete.set_content_type(content_type)
-      _request(nsc, delete)
+      request(nsc, delete)
     end
 
+    ###
+    # === Internal helper methods below this line. ===
+    #
+    # These are internal utility methods, not subject to backward compatibility
+    # concerns.
+    ###
+
     # Append the query parameters to given URI.
     #
     # @param [String] uri Controller address relative to https://host:port
@@ -114,59 +122,93 @@ def delete(nsc, uri, content_type = CONTENT_TYPE::XML)
     def parameterize_uri(uri, parameters)
       params = Hash.try_convert(parameters)
       unless params.nil? || params.empty?
-        uri = uri.concat(('?').concat(parameters.map { |k, v| "#{k}=#{CGI.escape(v.to_s)}" }.join('&'))) 
+        uri = uri.concat(('?').concat(parameters.map { |k, v| "#{k}=#{CGI.escape(v.to_s)}" }.join('&')))
       end
       uri
     end
 
-    def preserving_preference(nsc, pref)
-      begin
-        orig = _get_rows(nsc, pref)
-        yield
-      ensure
-        _set_rows(nsc, pref, orig)
-      end
-    end
-
-    ###
-    # Internal helper methods
-
     # Use the Nexpose::Connection to establish a correct HTTPS object.
-    def _https(nsc)
+    def https(nsc, timeout = nil)
       http = Net::HTTP.new(nsc.host, nsc.port)
+      http.read_timeout = timeout if timeout
       http.use_ssl = true
       http.verify_mode = OpenSSL::SSL::VERIFY_NONE
       http
     end
 
     # Attach necessary header fields.
-    def _headers(nsc, request)
+    def headers(nsc, request)
       request.add_field('nexposeCCSessionID', nsc.session_id)
       request.add_field('Cookie', "nexposeCCSessionID=#{nsc.session_id}")
     end
 
-    def _request(nsc, request)
-      http = _https(nsc)
-      _headers(nsc, request)
+    def request(nsc, request, timeout = nil)
+      http = https(nsc, timeout)
+      headers(nsc, request)
 
       # Return response body if request is successful. Brittle.
       response = http.request(request)
       case response
-      when Net::HTTPOK
-        response.body
-      when Net::HTTPCreated
+      when Net::HTTPOK, Net::HTTPCreated
         response.body
       when Net::HTTPForbidden
         raise Nexpose::PermissionError.new(response)
-      when Net::HTTPUnauthorized
-        raise Nexpose::PermissionError.new(response) 
+      when Net::HTTPFound
+        if response.header['location'] =~ /login/
+          raise Nexpose::AuthenticationFailed.new(response)
+        else
+          req_type = request.class.name.split('::').last.upcase
+          raise Nexpose::APIError.new(response, "#{req_type} request to #{request.path} failed. #{request.body}", response.code)
+        end
       else
         req_type = request.class.name.split('::').last.upcase
         raise Nexpose::APIError.new(response, "#{req_type} request to #{request.path} failed. #{request.body}", response.code)
       end
     end
 
-    def _get_rows(nsc, pref)
+    # Execute a block of code while presenving the preferences for any
+    # underlying table being accessed. Use this method when accessing data
+    # tables which are present in the UI to prevent existing row preferences
+    # from being set to 500.
+    #
+    # This is an internal utility method, not subject to backward compatibility
+    # concerns.
+    #
+    # @param [Connection] nsc Live connection to a Nepose console.
+    # @param [String] pref Preference key value to preserve.
+    #
+    def preserving_preference(nsc, pref)
+      begin
+        orig = get_rows(nsc, pref)
+        yield
+      ensure
+        set_rows(nsc, pref, orig)
+      end
+    end
+
+    # Get a valid row preference value.
+    #
+    # This is an internal utility method, not subject to backward compatibility
+    # concerns.
+    #
+    # @param [Fixnum] val Value to get inclusive row preference for.
+    # @return [Fixnum] Valid row preference.
+    #
+    def row_pref_of(val)
+      if val.nil? || val > 100
+        500
+      elsif val > 50
+        100
+      elsif val > 25
+        50
+      elsif val > 10
+        25
+      else
+        10
+      end
+    end
+
+    def get_rows(nsc, pref)
       uri = '/ajax/user_pref_get.txml'
       resp = get(nsc, uri, CONTENT_TYPE::XML, 'name' => "#{pref}.rows")
       xml = REXML::Document.new(resp)
@@ -178,7 +220,7 @@ def _get_rows(nsc, pref)
       end
     end
 
-    def _set_rows(nsc, pref, value)
+    def set_rows(nsc, pref, value)
       uri = '/ajax/user_pref_set.txml'
       params = { 'name'  => "#{pref}.rows",
                  'value' => value }
@@ -188,19 +230,5 @@ def _set_rows(nsc, pref, value)
         attr.value == '1'
       end
     end
-
-    def _row_pref_of(val)
-      if val.nil? || val > 100
-        500
-      elsif val > 50
-        100
-      elsif val > 25
-        50
-      elsif val > 10
-        25
-      else
-        10
-      end
-    end
   end
 end
diff --git a/lib/nexpose/scan.rb b/lib/nexpose/scan.rb
index cda7522b..9ff287d9 100644
--- a/lib/nexpose/scan.rb
+++ b/lib/nexpose/scan.rb
@@ -238,7 +238,7 @@ def scan_statistics(scan_id)
     #
     def past_scans(limit = nil)
       uri = '/data/scan/global/scan-history'
-      rows = AJAX._row_pref_of(limit)
+      rows = AJAX.row_pref_of(limit)
       params = { 'sort' => 'endTime', 'dir' => 'DESC', 'startIndex' => 0 }
       AJAX.preserving_preference(self, 'global-completed-scans') do
         data = DataTable._get_json_table(self, uri, params, rows, limit)
@@ -255,7 +255,7 @@ def past_scans(limit = nil)
     #   zip_file, if provided. Otherwise, returns raw ZIP binary data.
     #
     def export_scan(scan_id, zip_file = nil)
-      http = AJAX._https(self)
+      http = AJAX.https(self)
       headers = { 'Cookie' => "nexposeCCSessionID=#{@session_id}",
                   'Accept-Encoding' => 'identity' }
       resp = http.get("/data/scan/#{scan_id}/export", headers)
@@ -305,8 +305,8 @@ def import_scan(site_id, zip_file)
       post.set_content_type('multipart/form-data', boundary: data.bound)
 
       # Avoiding AJAX#request, because the data can cause binary dump on error.
-      http = AJAX._https(self)
-      AJAX._headers(self, post)
+      http = AJAX.https(self)
+      AJAX.headers(self, post)
       response = http.request(post)
       case response
       when Net::HTTPOK