Patent Publication Number: US-9900328-B2

Title: Web redirection for content scanning

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims the benefit of U.S. patent application Ser. No. 14/810,319, filed Jul. 27, 2015, which is a continuation of U.S. patent application Ser. No. 14/497,246, filed Sep. 25, 2014, which claims the benefit of priority to U.S. Provisional Patent Application No. 62/031,080, filed Jul. 30, 2014, which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     This specification generally relates to using redirect messages to implement content scanning. 
     The Internet is a global network of computers that provide information, such as web pages, to clients in response to requests. In some cases, this provided information may be cached in a location that can be accessed more quickly by clients than the computer that provided the information, such as a cache server. Subsequent requests for the same information may be fulfilled by the cache server rather than the remote computer, which may lead to the information being returned to the client faster. 
     SUMMARY 
     In general, one aspect of the subject matter described in this specification may be embodied in systems, and methods performed by data processing apparatuses that include the actions of receiving from a client a first request for a network resource, the first request including an original location of the network resource; determining that a response to the first request is to be analyzed; in response to determining that the response to the first request is to be analyzed, sending a redirect response to the client including a modified location for the network resource different than the original location; receiving a second request for the network resource from the client, the second request including the modified location; in response to receiving the second request for the network resource from the client: retrieving the network resource from the original location; determining that the retrieved network resource is suitable to send to the client; and in response to determining that the retrieved network resource is suitable, sending the retrieved network resource to the client. 
     Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and potential advantages of the subject matter will become apparent from the description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an example environment. 
         FIG. 2  is a message flow diagram of an example interaction between the components of the example environment to implement content scanning using redirect messages. 
         FIG. 3  is a message flow diagram of an example interaction between the components of the example environment to implement content scanning using redirect messages showing a case where a response to the particular request has been previously stored. 
         FIG. 4  is a message flow diagram of an example interaction between the components of the example environment showing a case where content scanning is not enabled for a particular request. 
         FIG. 5  is a flow chart of an example process of using redirect messages to implement content scanning. 
         FIG. 6  is a diagram of computing devices that may be used to implement the systems and methods described in this document. 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     The present disclosure generally relates to techniques for using redirection of client requests to perform content scanning. Many network protocols, such as Hypertext Transfer Protocol (HTTP), include redirection mechanisms allowing a server to instruct a client to fetch requested content from an alternate location, such as a different server identified by a different Uniform Resource Locator (URL). The present techniques selectively utilize these redirection mechanisms to direct client requests to a separate system that retrieves the requested content on behalf of the client. This configuration allows the requested content to be analyzed to determine whether the content is safe or otherwise suitable to return to the requesting client. 
     One example technique according to the present disclosure includes receiving from a client a first request for a network resource including an original location of the network resource. A determination may then be made that a response to the first request is to be analyzed, such as, for example, to determine if the response is suitable to return to the client. The determination may be based on the type of network resource requested, the original location of the resource, on the particular client making the request, or on other factors. 
     In response to determining that the response to the first request is to be analyzed, a redirect response is sent to the client including a modified location for the network resource different than the original location. In some cases, the modified location may be associated with a content scanning system operable to scan the requested content. A second request for the network resource is then received from the client including the modified location. In response to this second request, the network resource may be retrieved from the original location, and scanned or analyzed to determine whether it is suitable to return to the client. Suitability may be determined based on the results of a virus scan of the retrieved resource, on an analysis of the content of the retrieved resource, or on other factors. For example, if a virus scan of the retrieved resource reveals that the retrieved resource contains a harmful virus, then the retrieved resource would be deemed unsuitable, whereas if no virus if found the retrieved resource would be deemed suitable. Other examples of suitability analysis include inspecting the resource for objectionable content (e.g., pornography), prohibited subjects (e.g., terrorism), or other prohibited content and determining that the retrieved resource is not suitable if any such content is found. In general, essentially any appropriate, objective criteria can be used to perform the suitability analysis. In response to determining that the retrieved network resource is suitable, the retrieved network resource may be sent to the client. 
     The techniques described herein may provide several advantages. By using widely supported and well-known redirection mechanisms of standard protocols rather than custom protocols, the techniques described herein may be more widely applicable than previous techniques. The techniques also may allow for more flexible and configurable implementations of content scanning by allowing the decision to redirect to be made by a network management system rather than based on local rules stored at the client, or based on configuration specific to a particular application. 
       FIG. 1  is a diagram of an example environment  100 . As shown, the example environment includes one or more devices  130   a - c  connected to an internal network  110 . A network management system  120  and a scanning system  190  also connected to the internal network  110 . Network management system  110  is connected to a database  160 . The scanning system  190  and the network management system  120  connected to the Internet  150 . A website  180  is connected to the Internet  150 . In operation, one of the devices  130   a - c  may send a request to the website  180  via the internal network  110 . For example, a device may send an HTTP GET request including the URL of the resource hosted by the website  180 . Network management system  120  may intercept the request, and determine that the request is configured to be scanned. The network management system  120  may send a redirect message to the requesting device directing the device to the scanning system  190 . For example, the network management system  120  may send an HTTP response indicating that a redirect should occur including a new URL for the device to request. The new URL may identify the scanning system  190 , and may include an indication of the original URL that was requested. The requesting device may then send another request for the website  180  through the scanning system  190 . The scanning system  190  may determine that it has a stored copy of the response to the request, and may return the stored copy to the requesting device. The scanning system  190  may also determine that it does not have a stored copy of the response to the request, and may forward the request to the website  180  via the Internet  150 . The website  180  may respond to the request with a response, such as, for example, a webpage or other resource specified in the request. The scanning system  190  may receive this response from the website  180 , and scan the response to determine if it is suitable to return to the requesting device. The process is described in greater detail below. If the response is determined to be suitable, the scanning system  190  may then return the response to the requesting device over the internal network  110 . The scanning system  190  may also store the response so that it may respond to future requests with the stored copy. 
     As shown, the environment  100  includes an internal network  110 . In some implementations, the internal network  110  may be a wireless network provided by a corporation, educational institution, municipality, business, or other entity. Such a wireless network may utilize any standard wireless networking technology, including 802.11a, 802.11b, 802.11g, 802.11n, LTE, WiMax, CDMA or any other suitable wireless networking technology. In such implementations, the wireless network may be a public network in the sense that any device within range may connect to the network. Even though any device within range may connect to the internal network  110  in such configurations, the device still may be required to authenticate in order to access resources on the internal network  110  and/or on the Internet  150 . Such a configuration is often referred to as a Bring Your Own Device (BYOD) network in which users are free to use their own personal devices for connecting to the network. In some implementations, the entity that controls the internal network  110  may issue devices to users for use on the internal network  110 . The internal network  110  may also be a wired network, such as an Ethernet network. 
     Environment  100  also includes one or more devices  130   a - c . In some implementations, the one or more devices  130   a - c  include mobile devices, such as cellular telephones (e.g.,  130   a ), smartphones, tablets, laptops (e.g.,  130   b ) and other similar computing devices. The one or more devices  130   a - c  may also include wired devices such as desktop computer  130   c . The one or more devices  130   a - c  may also include servers. In some implementations, the one or more devices  130   a - c  include personal devices associated with one or more users. The one or more devices  130   a - c  may also include devices issued or owned by the entity that provides the internal network  110 , such as company-issued smartphones or laptops. In some implementations, the one or more devices  130   a - c  may include network access or web browsing software (e.g., a web browser) for accessing resources on the Internet  150 . 
     In some implementations, the devices  130   a - c  may include networking software configured to request websites from the Internet  150 . For example, the devices  130   a - c  may include web browser software allowing a user to browse websites on the Internet  150 . The web browser software may send requests for various resources from the websites, including, but not limited to, webpages, images, videos, software programs, files, and other types of resources. In some cases, the devices  130   a - c  may send requests and receive responses using the HTTP protocol. The devices  130   a - c  may also sin request and receive responses according to other network protocols, including, but not limited to, File Transfer Protocol (FTP), Simple Object Access Protocol (SOAP), Remote Procedure Call (RPC), or other protocols. 
     In some cases, the devices  130   a - c  may be configured to access the Internet  150  through the network management system  120 , such as, for example, by the network management system  120  be configured as the default gateway to access the Internet  150 . Clients  130   a - c  may also be configured to access the network management system  120  as a proxy server. In some implementations, the devices  130   a - c  may access the Internet  150  through a separate gateway (not shown), and the network management system  120  may passively monitor the requests and responses. 
     The environment  100  includes a network management system  120 . In some implementations, the network management system may be a server or set of servers connected to the internal network  110 . The network management system may be configured as a gateway between the internal network  110  and the Internet  150 , such that traffic directed to the Internet  150  passes through the network management system  120 . The network management system  120  may also be configured to passively monitor traffic on the internal network  110 , such as in a tap or span configuration. In some implementations, the network management system  120  may receive part of the traffic directed to the Internet  150 , such that certain traffic passes through the network management system  120 , and other traffic does not pass through the network management system  120 . In some implementations, the DNS functionality and the monitoring functionality of the network management system  120  may be implemented on separate servers in communication and coordination with one another. 
     The network management system  120  includes a redirect engine  122 . In operation, the redirect engine  122  identifies requests from the devices  130   a - c  for resources on the Internet  150 . The redirect engine  122  may determine that a particular request is configured to be scanned, such as by consulting content policies  162  stored in the database  160 . The redirect engine  122 , in response to determining that a request is configured to be scanned, may send a redirect response to the requesting device instructing the device to request the resource from the scanning system  190 . 
     For example, the device  130   a  may send an HTTP GET request over the internal network  110  directed to the website  180 . The HTTP GET request may include the URL “www.sample1.com/hello.gif,” indicating that the request is for an image named “hello.gif” from the website  180 . The network management system  120  may receive HTTP GET request from the internal network  110 . The redirect engine  122  may parse the HTTP GET request, and determine that the request should be redirected to the scanning system  190 . In some cases, the determination may be made based on the content policies  162 , which are described in greater detail below. In response to determining that the request should be redirected, the redirect engine  122  generates an HTTP redirect response including a URL associated with the scanning system  190  (e.g., “scanner.com”). In some cases, the URL may also include the URL from the original HTTP GET request (e.g., “http://scanner.com/r?url=www.sample1.com/hello.gif”). This may allow the scanning system  190  to determine what resource the device  130   a  is requesting. 
     In some implementations, the HTTP redirect response generated by the redirect engine  122  may be a “307 temporary redirect” response including the URL, which may be formatted as follows: 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                   
                 HTTP/1.1 307 temporary redirect 
               
               
                   
                 Refresh:0;url=http:// scanner.com/r?url=www.sample1.com/hello.gif 
               
               
                   
               
            
           
         
       
     
     The first line of the response includes a version indicator (“HTTP/1.1”) and a response code (“307 temporary redirect”). The second line of the response includes a refresh header indicating that the device should request the URL “http://scanner.com/r?url=www.sample1.com/hello.gif” after a delay of zero seconds. In some cases, HTTP redirect response generated by the redirect engine  122  may be a “200 OK” response including a refresh header. 
     In some cases, the redirect engine  122  may return a Hypertext Markup Language (HTML) document including an HTML meta-tag redirecting the browser to a new URL, as shown in the following example: 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                   
                 &lt;html&gt; 
               
               
                   
                 &lt;head&gt; 
               
               
                   
                 &lt;meta http-equiv=“Refresh” content=“0; url=http:// 
               
               
                   
                 scanner.com/r?url=www.sample1.com/hello.gif ” /&gt; 
               
               
                   
                 &lt;/head&gt; 
               
               
                   
                 &lt;body&gt; 
               
               
                   
                 &lt;p&gt;Please follow &lt;a href=“ http:// 
               
               
                   
                 scanner.com/r?url=www.sample1.com/hello.gif ”&gt;this link&lt;/a&gt;.&lt;/p&gt; 
               
               
                   
                 &lt;/body&gt; 
               
               
                   
                 &lt;/html&gt; 
               
               
                   
               
            
           
         
       
     
     The tag “&lt;meta http-equiv=“Refresh”&gt;” instructs a browser rendering the HTML to immediately request the specified URL. In some implementations, the redirect engine  122  may use additional techniques to cause the device  130   a  to request a different URL, including, but not limited to, a “302 found” response, a “301 moved permanently” response, a “303 see other” response, other HTTP responses including a refresh header, or other techniques. 
     The environment  100  also includes a database  160 . In some implementations, the database  160  may be stored on the same server as the network monitoring system  120 . The database  160  may also be stored on a separate server and accessed by the network monitoring system  120  over a network. The database  160  may be any proprietary or commercially available database system or format, including, but not limited to, MySQL®, Microsoft® SQLServer, IBM® DB2, Oracle®, SQLite, or any other suitable database system or format. The database  160  may also be a distributed database running on a plurality of servers. In some implementations, the database  160  may be a configuration file or set of configuration files associated with the network monitoring system  120 . 
     The database  160  may include configuration information specifying to the network management system  120  which requests should be redirected to the scanning system  190 . The configuration information may include content policies  162 , or other configuration information related to content scanning. The configuration information may specify particular network addresses, domain names, request types, requested resource types (e.g., file types by extension), or other objective criteria indicating requests that should be redirected to the scanning system  190 . 
     Environment  100  includes the scanning system  190 . In operation, the scanning system  190  may receive requests from the devices  130   a - c  set in response to the redirect from a network management system  120 . For example the scanning system  190  may determine whether a resource specified in the request is stored in the cache data  194 . If the resource is not stored, the scanning system  190  may retrieve the resource from the Internet  150 , and perform analysis on it to determine whether it is suitable to provide to the requesting device based on objective criteria. For example, the scanning system  190  may perform a virus scan on the requested resource, and may determine that the resource is suitable to provide to the requesting device based on the results of the virus scan (e.g., the resource is suitable if no viruses are detected). The scanning system  190  may also analyze the content of the retrieved resource, and may determine that the resource is suitable to provide to the requesting device based on the results of the virus scan (e.g., the resource is suitable if no prohibited content, such as pornography, is detected). In some cases, the scanning system  190  may consult the content policies  162  to determine whether the retrieved resource is suitable, such as, for example, by consulting a definition of prohibited content in the content policies  162 . For example, the content policies  162  may include a set of prohibited words, prohibited images, prohibited content subjects, prohibited file types, prohibited actions (such as scripting actions embedded in a web page), or other definitions. The scanning system  190  may, in the case of a request for an executable software program, execute the software program and observe its behavior to determine whether it is suitable, such as, for example, by executing the software program in a virtual machine. 
     In some cases, the scanning system  190  may include one or more storage devices for storing the requested content (not shown). These storage devices may include, but are not limited to, databases, file systems, memory devices, hard drives, cloud storage systems, or other devices. 
       FIG. 2  is a message flow diagram of an example interaction  200  between the components of the example environment to implement caching using redirect messages. The  205 , the device  130   a  sends a request for resource with the URL “www.sample1.com.” In some cases, the request is an HTTP GET request. The request may also be formatted according to other network protocols, such as those described herein. 
     At  210 , the network management system  120  interacts with the database  160  to determine that a response to the request should be scanned. For example, the network management system  120  may query and examine the content policies  162  to determine whether the request should be scanned, as described previously relevant  FIG. 1 . 
     At  215 , the network management system  120  redirects the device  130   a  to an alternate URL associated with the scanning system  190 . In some cases, this alternate URL may reference a resource on the scanning system  190  configured to perform the scanning functionality. The alternate URL may also include the original URL requested by the device  130   a  at  205 . In some cases, the network management system  120  redirects the device  130   a  by sending an HTTP redirect response. The redirect response may also be formatted according to other network protocols, such as those described herein. 
     At  220 , the device  130   a  sends a second request for the alternate URL to the scanning system  190 . In some implementations, the device  130   a  may perform a DNS lookup on a domain name included in the alternate URL to determine the address of the scanning system  190 . At  225 , the scanning system  190  determines that a response to the request sent at  205  is not stored by the scanning system  190 . At  230 , the scanning system  190  retrieves the requested resource from the website  180  denoted by the domain name “www.sample1.com.” 
     At  235 , the retrieved resources analyzed or scanned, such as, for example, according to the techniques described relative to  FIG. 1 . At  240 , a determination is made whether the retrieved resource is suitable to return to the device  130   a . If the scanning system  190  determines that the resource is not suitable to return to the device  130   a , the scanning system  190  returns an error indication to the device  130   a  ( 245 ). In some cases, the error returned by the scanning system  190  may be an HTTP response including an error code (e.g.,  404 ). 
     If the resource is determined to be suitable, the scanning system  190  stores the response received from the website  180  ( 245 ). At  250 , the scanning system  190  returns the response received from the website  180  to device  130   a.    
       FIG. 3  is a message flow diagram of an example interaction  300  between the components of the example environment to implement content scanning using redirect messages showing a case where a response to the particular request has been previously stored. The  305 , the device  130   a  sends a request for resource with the URL “www.sample1.com.” In some cases, the request is an HTTP GET request. The request may also be formatted according to other network protocols, such as those described herein. 
     At  310 , the network management system  120  interacts with the database  160  to determine that a response to the request should be scanned. For example, the network management system  120  may query and examine the content policies  162  to determine whether the request should be scanned, as described previously relevant  FIG. 1 . 
     At  315 , the network management system  120  redirects the device  130   a  to an alternate URL associated with the scanning system  190 . In some cases, this alternate URL may reference a resource on the scanning system  190  configured to perform the scanning functionality. The alternate URL may also include the original URL requested by the device  130   a  at  305 . In some cases, the network management system  120  redirects the device  130   a  by sending an HTTP redirect response. The redirect response may also be formatted according to other network protocols, such as those described herein. 
     At  320 , the device  130   a  sends a second request for the alternate URL to the scanning system  190 . In some implementations, the device  130   a  may perform a DNS lookup on a domain name included in the alternate URL to determine the address of the scanning system  190 . At  325 , the scanning system  190  determines that a response to the request sent at  305  is stored by the scanning system  190 . At  330 , the scanning system  190  returns the stored response to the client. 
     In some implementations, the scanning system  190  may not store responses from the website  180 , and may perform the suitability analysis on responses as they are received from the website  180 . In such a case, the scanning system  190  may for responses from the website  180  that are suitable to the device  130   a . In some cases, the scanning system  190  may store the retrieved resource for a configured period of time, after which the stored resource is deleted, causing it to be retrieved again and analyzed in response to the next request for the resource. 
       FIG. 4  is a message flow diagram of an example interaction  400  between the components of the example environment showing a case where content scanning is not enabled for a particular request. At  405 , the device  130   a  the device  130   a  sends a request for resource with the URL “www.sample1.com.” At  410 , the network management system  120  consults the database  160  to determine that the response to the request should not be scanned. At  415 , the network management system  120  forwards the request received at  305  to the website  180  and receives a response from the website  180 . At  420 , the network management system  120  returns the response received from the website  180  to the device  130   a.    
       FIG. 5  is a flow chart of an example process  500  of using redirect messages to implement content scanning. At  505 , a first request for a network resource is received from a client, the first request including an original location of the network resource. In some cases, receiving the first request for the network resource includes receiving an Hypertext Transfer Protocol (HTTP) GET request, and the original location for the network resource includes a Uniform Resource Locator (URL) for the network resource. 
     At  510 , it is determined that a response to the first request is to be analyzed. In some cases, determining that the response to the first request is to be analyzed includes determining that a domain name associated with the network resource is included in a list of domain names to be analyzed. Determining that the response to the first request is to be analyzed may be based at least in part on a resource type associated with the network resource. In some cases, the resource type may be a video file, an archive file, an executable file, an image file, or other types of resources. In some implementations, the resource type associated with the network resource is determined based on a file extension included in the original location. Determining that the response to the first request is to be analyzed may be based at least in part on a category associated with the network resource. 
     At  515 , in response to determining that the response to the first request is to be analyzed, a redirect messages is sent to the client including a modified location for the network resource. In some implementations, sending the redirect response to the client includes sending an HTTP redirect message to the client, and the modified location includes a URL associated with an analysis server and the URL for the network resource. In some cases, determining that the response to the first request is to be analyzed is based at least in part on a domain name included in the original location for the network resource. 
     At  520 , a second request for the network resource is received from the client, the second request including the modified location. 
     Actions  525  through  535  are performed in response to receiving the second request for the network resource from the client. At  525 , the network resource is retrieved from the original location. 
     At  530 , it is determined that the retrieved network resource is suitable to send to the client. In some cases, determining that the retrieved network resource is suitable to send to the client includes scanning the retrieved network resource for malicious content, wherein the determination is based at least in part on a result of the scanning. In some implementations, scanning the retrieved network resource for malicious content includes scanning the retrieved network resource for viruses. In some cases, the retrieved network resource is an executable program, and determining that the retrieved network resource is suitable to send to the client includes executing the retrieved network resource in a virtual environment, and the determination is based at least in part on an observed behavior of the retrieved network resource during execution. 
     At  535 , in response to determining that the retrieved network resource is suitable, the retrieved network resource is sent to the client. 
     In some cases, the network resource is a first network resource, and a first request for a second network resource different than the first network resource is received from the client, the request including an original location for the second network resource. A redirect response may be sent to the client including a modified location for the second network resource. A second request for the second network resource may then be received from the client, the second request including the modified location. In response to receiving the second request for the second network resource from the client, a determination may be made that that the retrieved network resource is not suitable to send to the client, and an indication may be sent to the client that the network resource is not suitable. 
     In some implementations, the client is a first client, and a third request for the network resource is received from a second client, the third request including the original location for the network resource. A redirect response is sent to the second client including the modified location for the network resource. A fourth request for the network resource is received from the second client, the fourth request including the modified location. In response to receiving the fourth request for the network resource from the second client, a determination is made that the network resource has been previously determined to be suitable, a stored version of the network resource is sent to the second client. 
       FIG. 6  is a block diagram of computing devices  600 ,  650  that may be used to implement the systems and methods described in this document, as either a client or as a server or plurality of servers. Computing device  600  is intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. Computing device  650  is intended to represent various forms of mobile devices, such as personal digital assistants, cellular telephones, smartphones, and other similar computing devices. Additionally computing device  600  or  650  can include Universal Serial Bus (USB) flash drives. The USB flash drives may store operating systems and other applications. The USB flash drives can include input/output components, such as a wireless transmitter or USB connector that may be inserted into a USB port of another computing device. The components shown here, their connections and relationships, and their functions, are meant to be exemplary only, and are not meant to limit implementations of the inventions described and/or claimed in this document. 
     Computing device  600  includes a processor  602 , memory  604 , a storage device  606 , a high-speed interface  608  connecting to memory  604  and high-speed expansion ports  610 , and a low speed interface  612  connecting to low speed bus  614  and storage device  606 . Each of the components  602 ,  604 ,  606 ,  608 ,  610 , and  612 , are interconnected using various busses, and may be mounted on a common motherboard or in other manners as appropriate. The processor  602  can process instructions for execution within the computing device  600 , including instructions stored in the memory  604  or on the storage device  606  to display graphical information for a GUI on an external input/output device, such as display  616  coupled to high speed interface  608 . In other implementations, multiple processors and/or multiple buses may be used, as appropriate, along with multiple memories and types of memory. Also, multiple computing devices  600  may be connected, with each device providing portions of the necessary operations (e.g., as a server bank, a group of blade servers, or a multi-processor system). 
     The memory  604  stores information within the computing device  600 . In one implementation, the memory  604  is a volatile memory unit or units. In another implementation, the memory  604  is a non-volatile memory unit or units. The memory  604  may also be another form of computer-readable medium, such as a magnetic or optical disk. 
     The storage device  606  is capable of providing mass storage for the computing device  600 . In one implementation, the storage device  606  may be or contain a computer-readable medium, such as a floppy disk device, a hard disk device, an optical disk device, or a tape device, a flash memory or other similar solid state memory device, or an array of devices, including devices in a storage area network or other configurations. A computer program product can be tangibly embodied in an information carrier. The computer program product may also contain instructions that, when executed, perform one or more methods, such as those described above. The information carrier is a computer- or machine-readable medium, such as the memory  604 , the storage device  606 , or memory on processor  602 . 
     The high speed controller  608  manages bandwidth-intensive operations for the computing device  600 , while the low speed controller  612  manages lower bandwidth-intensive operations. Such allocation of functions is exemplary only. In one implementation, the high-speed controller  608  is coupled to memory  604 , display  616  (e.g., through a graphics processor or accelerator), and to high-speed expansion ports  610 , which may accept various expansion cards (not shown). In the implementation, low-speed controller  612  is coupled to storage device  606  and low-speed expansion port  614 . The low-speed expansion port, which may include various communication ports (e.g., USB, Bluetooth, Ethernet, wireless Ethernet) may be coupled to one or more input/output devices, such as a keyboard, a pointing device, a scanner, or a networking device such as a switch or router, e.g., through a network adapter. 
     The computing device  600  may be implemented in a number of different forms, as shown in the figure. For example, it may be implemented as a standard server  620 , or multiple times in a group of such servers. It may also be implemented as part of a rack server system  624 . In addition, it may be implemented in a personal computer such as a laptop computer  622 . Alternatively, components from computing device  600  may be combined with other components in a mobile device (not shown), such as device  650 . Each of such devices may contain one or more of computing device  600 ,  650 , and an entire system may be made up of multiple computing devices  600 ,  650  communicating with each other. 
     Computing device  650  includes a processor  652 , memory  664 , an input/output device such as a display  654 , a communication interface  666 , and a transceiver  668 , among other components. The device  650  may also be provided with a storage device, such as a microdrive or other device, to provide additional storage. Each of the components  650 ,  652 ,  664 ,  654 ,  666 , and  668 , are interconnected using various buses, and several of the components may be mounted on a common motherboard or in other manners as appropriate. 
     The processor  652  can execute instructions within the computing device  650 , including instructions stored in the memory  664 . The processor may be implemented as a chipset of chips that include separate and multiple analog and digital processors. Additionally, the processor may be implemented using any of a number of architectures. For example, the processor  610  may be a CISC (Complex Instruction Set Computers) processor, a RISC (Reduced Instruction Set Computer) processor, or a MISC (Minimal Instruction Set Computer) processor. The processor may provide, for example, for coordination of the other components of the device  650 , such as control of user interfaces, applications run by device  650 , and wireless communication by device  650 . 
     Processor  652  may communicate with a user through control interface  658  and display interface  656  coupled to a display  654 . The display  654  may be, for example, a TFT (Thin-Film-Transistor Liquid Crystal Display) display or an OLED (Organic Light Emitting Diode) display, or other appropriate display technology. The display interface  656  may comprise appropriate circuitry for driving the display  654  to present graphical and other information to a user. The control interface  658  may receive commands from a user and convert them for submission to the processor  652 . In addition, an external interface  662  may be provided in communication with processor  652 , so as to enable near area communication of device  650  with other devices. External interface  662  may provide, for example, for wired communication in some implementations, or for wireless communication in other implementations, and multiple interfaces may also be used. 
     The memory  664  stores information within the computing device  650 . The memory  664  can be implemented as one or more of a computer-readable medium or media, a volatile memory unit or units, or a non-volatile memory unit or units. Expansion memory  674  may also be provided and connected to device  650  through expansion interface  672 , which may include, for example, a SIMM (Single In Line Memory Module) card interface. Such expansion memory  674  may provide extra storage space for device  650 , or may also store applications or other information for device  650 . Specifically, expansion memory  674  may include instructions to carry out or supplement the processes described above, and may include secure information also. Thus, for example, expansion memory  674  may be provide as a security module for device  650 , and may be programmed with instructions that permit secure use of device  650 . In addition, secure applications may be provided via the SIMM cards, along with additional information, such as placing identifying information on the SIMM card in a non-hackable manner. 
     The memory may include, for example, flash memory and/or NVRAM memory, as discussed below. In one implementation, a computer program product is tangibly embodied in an information carrier. The computer program product contains instructions that, when executed, perform one or more methods, such as those described above. The information carrier is a computer- or machine-readable medium, such as the memory  664 , expansion memory  674 , or memory on processor  652  that may be received, for example, over transceiver  668  or external interface  662 . 
     Device  650  may communicate wirelessly through communication interface  666 , which may include digital signal processing circuitry where necessary. Communication interface  666  may provide for communications under various modes or protocols, such as GSM voice calls, SMS, EMS, or MMS messaging, CDMA, TDMA, PDC, WCDMA, CDMA2000, or GPRS, among others. Such communication may occur, for example, through radio-frequency transceiver  668 . In addition, short-range communication may occur, such as using a Bluetooth, WiFi, or other such transceiver (not shown). In addition, GPS (Global Positioning System) receiver module  670  may provide additional navigation- and location-related wireless data to device  650 , which may be used as appropriate by applications running on device  650 . 
     Device  650  may also communicate audibly using audio codec  660 , which may receive spoken information from a user and convert it to usable digital information. Audio codec  660  may likewise generate audible sound for a user, such as through a speaker, e.g., in a handset of device  650 . Such sound may include sound from voice telephone calls, may include recorded sound (e.g., voice messages, music files, etc.) and may also include sound generated by applications operating on device  650 . 
     The computing device  650  may be implemented in a number of different forms, as shown in the figure. For example, it may be implemented as a cellular telephone  680 . It may also be implemented as part of a smartphone  682 , personal digital assistant, or other similar mobile device. 
     Various implementations of the systems and techniques described here can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and/or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device. 
     These computer programs (also known as programs, software, software applications or code) include machine instructions for a programmable processor, and can be implemented in a high-level procedural and/or object-oriented programming language, and/or in assembly/machine language. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, apparatus and/or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term “machine-readable signal” refers to any signal used to provide machine instructions and/or data to a programmable processor. 
     To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input. 
     The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (“LAN”), a wide area network (“WAN”), peer-to-peer networks (having ad-hoc or static members), grid computing infrastructures, and the Internet. 
     The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. 
     Although a few implementations have been described in detail above, other modifications are possible. In addition, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.