CA2781178C - Method, storage medium and hosting device for supporting a statically configured guest device - Google Patents

Abstract

A method, system, and device for allowing a guest device to communicate with a network, where the hosting gateway IP address is different than the guest gateway IP address. The method comprises several steps, as follows; listening for ARP requests and detecting a first ARP request from the guest device, requesting the guest gateway hardware address corresponding to the guest gateway IP address, and upon detection of the first ARP request, broadcasting a gratuitous ARP packet requesting for the guest device hardware address corresponding to the guest device IP address. The gratuitous ARP packet triggers in the guest device an update of its ARP table, thereby allowing the guest device to communicate on the network via the hosting system.

Description

Method, Storage Medium and Hosting Device for supporting a statically configured Guest Device FIELD OF THE INVENTION

The present invention relates generally to network communications and more specifically, to a method, a system, and a device for supporting statically configured devices on a foreign network.

BACKGROUND OF THE INVENTION

In the past few years, a plethora of devices equipped with wireless communication means have emerged, and particularly means for wired and wireless internet access. Many such devices are mobile devices including, but not limited to, cell phones, smart phones, tablet computers, portable computers, game consoles, and the like. Many such devices use communication protocols which enable the user to easily connect to a foreign network.

Indeed, although these devices may be configured to access a "home" network, in the sense of a base network (which could be a home but could also be an office, a store, etc.), often these devices are mobile and as such they are susceptible to be used in a new location where wired or wireless Internet services are offered by the property. This is hereinafter a "foreign network". Examples of foreign networks are wired and wireless networks present in hotels, convention centers, restaurants and condos.

Nowadays, mobile devices are generally provided with means to automatically configure a communication path between the foreign network and the mobile device, for example using DHCP (Dynamic Host Configuration Protocol).

However, there exist many devices which are, for example, configured with a static IP address, have a locked IP configuration, such as corporately-owned and controlled devices, or are otherwise lacking in capability to easily connect to a foreign network. Such devices may require deep knowledge to configure the mobile device for communication,

2 which is outside the reach of most users. In other cases, the user cannot reconfigure the device due to company policies.

Therefore, various solutions for enabling communication have been tried. One such solution is the one proposed by Nomadix, Inc., as described in US patent no.
7,554,995.
This patent describes a system for connecting a user device to a network where the user device settings, the network settings, or both are unknown. Request packets transmitted by the user device are intercepted and a response packet is forged in response to the request from the user device. While this solution allows the user device to communicate with the foreign network, it requires the hosting system to send a response to a request that was not addressed to it.

It is believed that there is still a need for a method, system, and device which allows a device that is statically configured to communicate on a foreign network. It would also be desirable for the method, system, and device to receive confirmation from the guest device that the communication has been established.

SUMMARY OF THE INVENTION

The present method provides a method performed by a hosting system, to allow a guest device to communicate with a network via the hosting system. The guest device has a static IP address and a guest hardware address. The guest device is configured to communicate through a guest gateway having a guest gateway IP address and a guest gateway hardware address. The hosting system includes a hosting gateway having at least one interface provided with a hosting gateway IP address and a hosting gateway hardware address. The hosting gateway IP address is different than said guest gateway IP address. The method comprises the following steps:

a) listening for ARP requests;

b) detecting from the ARP requests a first ARP request from the guest device, requesting the guest gateway hardware address corresponding to the guest gateway IP address, said the ARP request including:

- the guest device IP address;

3 - the guest gateway IP address; and - the guest device hardware address;

c) upon detection of the first ARP request of step a), broadcasting an ARP
packet including at least:

- the guest gateway IP address; and - the hosting gateway hardware address, wherein destination and source IP addresses correspond to the guest gateway IP address;

the ARP packet triggering in the guest device an update of an ARP table of the guest device, said update consisting of associating the hosting gateway hardware address to the guest gateway IP address; and d) building a route allowing the hosting system to send network packets to the guest device.

The method thereby allowing the guest device to communicate with said network via the hosting system.

In one embodiment, the ARP packet broadcas in step c) is an announcement packet.

In one embodiment, the method further includes a step of broadcasting a gratuitous ARP
packet, requesting for the guest device hardware address corresponding to the guest device IP
address, said gratuitous ARP packet including:

- the guest device IP address;

- the guest gateway IP address; and - the hosting gateway hardware address;
said step being performed after step c).

In one embodiment, the ARP packet broadcast in step c) is a gratuitous ARP
packet, requesting for the guest device hardware address corresponding to the guest device IP
address, said gratuitous ARP packet further including:

4 - the guest device IP address.

In one embodiment, the method includes a step of receiving at the hosting gateway an ARP
response from the guest device, the ARP response including - the guest device IP address;

s - the guest device hardware address;
- the hosting gateway IP address; and - the hosting gateway hardware address, the ARP response allowing the hosting gateway to confirm proper update of the ARP table, this step being performed after step c).

1o In one embodiment, the step of building a route includes generating a first routing table and adding a first route linking the guest device IP address with the hosting gateway IP address of said first interface on which the first ARP request from the guest device was received.

In one embodiment, the method comprises a step of associating in a storage module the guest device hardware address with the hosting gateway hardware address of said first interface.

15 In one embodiment, the method comprises a step of monitoring packets received from the guest device, and when the packets are received on a different interface than said first interface, the method further comprises the steps of:

e) broadcasting a second ARP packet including:
- the guest gateway IP address; and 20 - the guest device hardware address;

f) updating the storage module by associating said different interface of the hosting gateway with the guest gateway.

In one embodiment, the method includes a step of deleting the first route from said routing table;
and adding a second route in said routing table linking the guest device IP
address with an IP
25 address of said different interface of the hosting system.

In one embodiment, the method includes a step of receiving from the guest device a network packet other than an ARP request, the network packet including the hosting gateway IP address and the hosting gateway hardware address.

In one embodiment, the method comprises a step of receiving network packets from other

5 devices external to the network, and exchanging these network packets with said guest device.
The steps of the method can be performed via a wired or wireless link(s).

According to another aspect of the invention, a processor-readable storage medium for a hosting system is provided, for allowing a guest device to communicate with a network. The guest device has a static IP address and a guest device hardware address, the guest device being configured to communicate through a guest gateway provided with a guest gateway IP
address and a guest gateway hardware address. The hosting system includes a hosting gateway having at least one interface provided with a hosting gateway IP
address and a hosting gateway hardware address. The hosting gateway IP address is different than said guest gateway IP address. The processor-readable storage medium comprises instructions for execution by the processor to:

- listen to ARP requests, - detect from the ARP requests, a first ARP request from the guest device, requesting the guest gateway hardware address corresponding to the guest gateway IP address, the first ARP request including:

- the guest device IP address;

- the guest gateway IP address; and - a guest device hardware address;

instruct of a detection of the first ARP packet; and generate and broadcast an ARP packet, including:
^ the guest gateway IP address; and ^ the hosting gateway hardware address;

said ARP packet triggering in the guest device an update of an ARP table of the guest device, said update consisting associating hosting gateway hardware address to the guest gateway IP address; and

6 - build a route allowing the hosting system to send network packets to the guest device.

According to yet another aspect of the invention, a hosting device is provided, for allowing a guest device to communicate with a network. The guest device has a static IP
address and a guest device hardware address. The guest device is configured for communicating through a guest gateway provided with a guest gateway IP address and a guest gateway hardware address. The hosting device has at least one interface provided with a hosting gateway IP
address and a hosting gateway hardware address. The hosting gateway IP address is different than said guest gateway IP address. The device includes - a memory;

- a listener module stored in the memory and including:

- listening means for listening to ARP requests, - detecting means for detecting a first ARP request from the guest device, requesting the guest gateway hardware address corresponding to the guest gateway IP address, said first ARP request including:

= the guest device IP address;

= the guest gateway IP address; and = the guest device hardware address;

- instructing means for instructing of a detection of the first ARP packet;
and - a broadcaster module stored in the memory and including means for generating and sending a gratuitous ARP packet, upon being instructed by the instructing means of the detection of the first ARP request, the gratuitous ARP packet asking for the guest device hardware address corresponding to the guest device IP address, said gratuitous ARP packet including:

- the guest device IP address;

- the guest gateway IP address; and - the hosting gateway hardware address;

7 - a route builder module, for building a route between said at least one interface and said guest device;

- a processor for executing the listener, the broadcaster and the route builder modules;

the hosting device thereby allowing the guest device to communicate on said network.

In one embodiment of the hosting device, it further includes a storage module including entries associating said guest gateway with one of said several interfaces, and preferably also includes a clean-up module, for querying the storage module and deleting entries which have not been updated after a predetermined amount of time.

In the present description, a gratuitous ARP packet is a broadcast ARP packet which does require a reply from the client. An ARP announcement is a broadcast ARP
request packet which does not include the IP address of the guest device in the target address, and thus requires no reply.

It will be appreciated that the present invention can be implemented either by software, is hardware, or a combination of both. The method can be performed by a software application stored in a memory and run by a processor, by custom made logical circuit chips, such as FPGAs, and the like.

A hosting system can include one or several devices, comprised in a single enclosure or distributed in several ones.

The invention will be better understood from a reading of the non-restrictive description that follows of a preferred embodiment thereof, and upon referring to the appended drawings.
To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of this application.

BRIEF DESCRIPTION OF THE DRAWINGS

8 Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

FIGURE 1 is a schematic view of a network device and a system within its environment, according to one embodiment of the invention.

FIGURE 2 is a block diagram illustrating components of the hosting system, according to one embodiment of the invention.

FIGURE 3A is schematic diagram, according to an embodiment of the invention.
FIGURE 3B is 1o schematic diagram illustrating according to one embodiment of the invention.

FIGURE 4A is block diagram illustrating steps of the method, according to an embodiment of the invention. FIGURE 4B is another block diagram illustrating steps of the method, according to another embodiment of the invention.

FIGURE 5 is a flowchart illustrating a prior art network device.

i5 FIGURE 6 is a table showing partial network traces generated following the method according to one embodiment of the invention.

FIGURE 7 is a block diagram illustrating components of the hosting system, according to another embodiment of the invention.

FIGURE 8 is block diagram illustrating steps of the method, according to an embodiment of the 20 invention.

DETAILED DESCRIPTION OF THE INVENTION

In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction or to the arrangements of the components set forth in the following description 25 or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology

9 and terminology employed herein are for the purpose of the description and should not be regarded as limiting.

The invention generally relates to network communications and static IP
support which, in one embodiment, includes software running on a system such as a computer, a server, a router, or a specially designed network device provided with at least two network interfaces.
Such system is referred to as a hosting system or hosting device. When in use, the hosting system listens for ARP request packets destined for foreign networks and issues an ARP
request broadcast packet, causing the requesting device to insert an entry in its internal ARP
table which results in a communication path between the originator, or requesting device of 1o the foreign network, and itself.

One objective of the present invention is to provide a system and/or device which supports statically configured devices on foreign network(s). In other words, the present invention aims at supporting one or several guest devices in a foreign network where the guest devices do not support, or are not configured to use, standard network protocols which automatically configure devices to communicate on foreign networks.

Another objective is to provide a system, a method and/or a hosting device for supporting statically configured devices on foreign networks that need to connect to a TCP/IP
network but are either not compatible with the DHCP protocol or are not configured to operate with DHCP. In some cases, it may also be that devices configured for DHCP are nevertheless incompatible because of client DHCP restrictions, and fall back to IPV4 Link-Local Addressing (addresses set aside in the 169.254/16 range). The devices are typically referred to as "guest"
computers, laptop, tablets, smartphones, or other TCP/IP enabled devices which are not permanently installed within the foreign network.

It should be noted that not all of the particular components, configurations, and steps 2s described in the following detailed description of embodiments are essential to the invention and thus should not be taken in their restrictive sense, i.e. they should not be taken as to limit the present invention. It is to be understood, as also apparent to a person skilled in the art, that other suitable components and cooperations therein between, as well as other suitable configurations, organizations, and/or architectures may be used for the system, network device, 3o and method according to the present invention, as will be briefly explained herein and as can be easily inferred herefrom, by a person skilled in the art, without departing from the invention.
Moreover, the order of the steps provided herein should not be taken as to limit the scope of the invention, as the sequence of the steps may vary in a number of ways without affecting the scope or working of the invention, as can also be understood.

5 Furthermore, in the context of the present invention, the expressions "laptop", "mobile device", "game console", "tablet", "cellular phone", "mobile phone", "guest device" and any other equivalent expression and/or compound words thereof known in the art will be used interchangeably. Furthermore, the terms "host user" and "guest user" refer to the user of the host mobile or fixed device. The terms "hosting system" , "network device", and "hosting device"

10 refer to a system through which the guest/user devices must connect in order to communicate with the local network (of the hotel, condo tower, etc.) or with other foreign networks. A hosting system can include many devices distributed in different enclosures, while the hosting device is typically a network gateway.

With reference to Figure 1, a network 10 is shown. The network 10 includes different is types of devices: communication devices 12; a hosting device 14, for example a gateway appliance; guest devices 16, that are connected to the network, such as laptops, mobile phones, tablets, and that are either properly configured or use the DHCP
protocol; and other guest devices 18, which do not support DHCP, or are not configured to use DHCP. In other words, guest devices 18 are configured with static IP addresses.

The hosting device 14 includes a memory 20, a processor 22, and a first network interface 24 through which it can communicate with the communication device 12 and/or directly with the guest devices. Stored in the memory 20 is a software application which includes different modules or functions, some of which allow guest devices 18 to communicate with the network 10, even if they are configured to communicate with a base or home network that is different than the network 10. Network 10 can also be referred to as a "foreign network" when considered from the view point of the guest device.
The hosting device 14 can be, for example, a computer, a server, a router, or any specially designed network device which includes at least a network interface 24 and preferably another network interface 25.

11 It is worth noting that it can be considered to include, within the hosting device 14, the communication capabilities of device 12.

In brief, the hosting device 14 listens on its network interface 24 for ARP
request packets destined for foreign networks. The hosting device 14 will issue, on the network interface 24a, an ARP packet, which can be either one of an ARP announcement or a gratuitous ARP packet, to establish a communication path between the originator of the ARP request and itself, the originator being one of the guest devices 18. The devices 16, 18 are connected to the communication device 12, wired or wirelessly, and the communication device 12 is in turn linked to the hosting device 14, also referred to as a gateway appliance.
Of course, as mentioned previously, while in Figure 1 the communication device

12 and the hosting device 14 are shown as two distinct apparatuses, they can also be integrated in a single enclosure.

Now, the steps of the method which allow the guest device 18 to communicate with the network 10 of Figure 1 will be explained by referring to Figures 2 to 4.
The guest device 18, which can also be referred to as a foreign device when considered from the view point of the hosting device, is configured with a static IP address and is provided with a hardware address, such as a MAC address (Media Access Control address). In the case illustrated, the guest device 18 is configured with a static IP address set to 192.168.40.15, a subnet mask set to 255.255.255.0, a default gateway set to 192.168.40.1, and a MAC
address set to AA:BB:CC:DD:EE:FF. The default gateway, also referred to as the guest gateway, is the network device through which the guest device generally communicates when accessing other networks from its base or home location.

The guest device 18 can be, for example, the laptop of a user which is set to communicate with a home or base router. This router would thus be configured with the default or "guest" gateway IP address, in this case 192.168.40.1. Just as for the guest device, the home/base router has a hardware address, which is typically a MAC
address.

As it is well known to people skilled in IP networking, the Address Resolution Protocol (or ARP) is used to connect the Network Layer (OSI Layer 3) to the Data-Link Layer (OSI Layer 2). In other words, the ARP is used to link IP addresses to Ethernet addresses (or MAC
3o Addresses). For a first device to communicate with a second device on a network, the first device must know the Ethernet MAC address of that second device. If the second device is not on the LAN (Local Area Network), the first device needs to go through its default gateway, which is typically a router. In this case, the router will be the destination MAC
address that the first device will communicate with.

As such, when the guest device 18 wants to communicate with other devices or networks, it will first verify in its ARP table to see whether the MAC address of the default gateway is known. An ARP table allows to link an IP address with a MAC
address. Since the content of the ARP table is only kept for a short period of time, and as long as it is used, the MAC address corresponding to the default gateway is unknown when arriving in the location of the new hosting network. In other words, the guest device 18 wants to speak to its default gateway but the MAC address of the default gateway is not listed in the ARP
table. The guest device 18 thus sends a broadcast ARP request that says "who has 192.168.40.1 and what is your MAC address?". The ARP request includes the guest device IP
address, the guest gateway IP address, and the guest device hardware or MAC address.

The hosting device, also referred to as hosting gateway 14, is configured with a hosting gateway IP address and is provided with a hosting gateway hardware address, such as a MAC address. In this case, the IP address of the hosting gateway is set to 10.10.1.1, the subnet mask is set to 255.255.255.0, the default gateway is set to 10.10.1.254 and the MAC address is set to Al:B1:C1:D1:E1:F1. The hosting gateway IP address is thus different than the guest gateway IP address, and the guest device would typically not be able to communicate through the hosting gateway without the invention, as best shown in Figure 5.
Turning now to Figure 2, according to the invention the network device is provided with a listener module 26 which listens to ARP requests. When the listener module 26 detects an ARP request from a foreign network, which can be referred to as the first ARP
request 32, it drops the initial request, and the listener module 26 instructs a broadcaster module 28 to generate a gratuitous ARP packet, referenced by numeral 34. The gratuitous ARP packet 34 says "who has 192.168.40.15 and what is your MAC address?". In other words, the hosting device 14 creates gratuitous ARP broadcast packet to teach the device 18 that the MAC address of the network device corresponds to the foreign network default gateway IP address.

13 As best shown in Figures 3A and 4A, the first ARP request 32 includes the guest device IP address, 192.168.40.15, the guest gateway IP address, 192.168.40.1, and the guest device hardware address, AA:BB:CC:DD:EE:FF. A tailored gratuitous ARP
packet 34 is sent from the hosting device 14 to the guest device 18. This gratuitous ARP
34 sent by s the hosting device 14 includes the guest device IP address, 192.168.40.15, the guest gateway address,192.168.40.1, and the hosting gateway hardware address, A1:B1:C1:D1:E1:F1.

Still referring to Figures 3A and 4A, after receiving the first ARP request 34, the hosting device 14 will update its ARP table with the IP address and the hardware address of 1o the guest device. Of course, this step can be performed either before, after, or while sending the gratuitous ARP packet 34.

When receiving the gratuitous ARP packet 34, the guest device 18 will automatically update its ARP table, thus associating the IP address 192.168.140.1 with the MAC address A1:B1:C1:D1:E1:F1. The guest device 18 will then be able to communicate with the hosting 15 device 14 and access other devices or networks via the network device, the network device communicating with the guest device as if it were the guest gateway.

According to the ARP protocol, the guest device 18 will reply to gratuitous ARP
packet 34 with the ARP response 36 which includes its IP and MAC address, and the hosting gateway IP and MAC address. The ARP response 36 essentially says 20 "192.168.40.15 is at AA:BB:CC:DD:EE:FF, and 192.168.40.1 is at A1:B1:C1:D1:E1:F1".

The present method advantageously respects the ARP protocol, in the sense that there is no "mangle" response sent to the first ARP request 32. It also allows the hosting device to receive a confirmation that the guest device 18 has indeed updated its ARP table.
Many anti-virus programs monitor ARP responses and may drop mangled ARP
responses.
25 Since it is the gratuitous ARP packet 34 that is sent from the network device/hosting gateway, the requests are not monitored in such way, and the probabilities that the gratuitous ARP packet will be dropped are smaller than that for a mangled ARP
response.

Indeed, Request for Comments ( RFC) 5227 proposes an Internet standards track protocol for the Internet community, noting that unsolicited ARP replies may be dropped, but not 3o ARP requests.

14 Referring to Figures 3B and 4B, an alternate method consist of having the hosting device 14 to sending an ARP announcement packet once an ARP request from a foreign/guest device 18 has been detected. The ARP announcement packet includes the hosting hardware address, and the guest gateway IP address for both the source and destination addresses.
When the guest device 18 will receive this ARP announcement, it will automatically update its ARP table, associating the IP address of its default gateway to the MAC
address of the hosting device. In order to ensure that the guest device has updated its ARP table, the hosting device sends a gratuitous ARP packet including a request for the MAC address associated to the IP
address of the guest device. The guest device will reply to this ARP request with an ARP reply, which provides the hosting device with a confirmation that the guest device 18 has indeed updated its ARP table. After the ARP Announcement, the arp request of the guest device is optional, although preferable since the hosting system will receive a confirmation from the guest device.
Once the two devices are able to communicate with each other, the network device 14 will receive network packets other than ARP requests, which will include the hosting gateway hardware address. The hosting gateway 14 will also receive network packets destined to the guest device 18, via its second network interface 25, and will transmit these packets to the guest device 18. The hosting device will then act as a middleware, changing the guest gateway IP address with his own IP address and exchanging network packets with the local or external network(s) 15 and the guest device 18.

Optionally, the hosting device 14 can include a route builder 30, to build a route, preferably a TCP/IP route, dedicated to the guest device 18. This route allows communication from the hosting device 14, or server, back to the guest device 18. This route will allow the guest device 18 to access external networks other than network 10.

Of course, the first ARP request 32, the gratuitous ARP packet 34, the ARP
response 36 from the guest device 18, and the following network packets can be sent via wired or wireless links. While the hardware addresses are typically MAC addresses, the use of another hardware address format can be considered.

The following paragraphs describe in more detail the different modules of the hosting system, and refer to Figures 1 to 4B. As explained previously, these modules can also be considered as elements, functions, or instructions stored on a processor-readable medium.

5 A. The Listener The listener module or listener element monitors all packets on a network interface and identifies ARP requests for foreign networks. It comprises listening means 38, detecting means 40, and instructing means 42. The listening means 38 listens for ARP
requests, the detecting means 40 is able to detect ARP requests from foreign networks and instead of 10 dropping them, it uses the information they contain to update its ARP
table. The instructing means is linked to the detecting means. They inform the broadcaster module of the ARP
request.

Foreign network ARP packets are ARP request packets that are issued by a device that is not in the same broadcast domain as the network interface listened on.

15 The Route Builder The Route Builder module or element creates a TCP route on the hosting system.
The Route Builder element creates a TCP route on the hosting system that will be specifically used for the guest. The TCP route is used to return packets to the guest device.
Since the guest device considers the gateway created as being in its local network, no route is needed outward from the guest device. However, one is needed for the hosting system to deliver packets back to the guest device. However, if the route builder determines that the route already exists from a previous communication with the guest, and that the route is still valid, no new route is created. If a route exists that is not valid, for any reason, that route is deleted before creating a new route.

The Route Builder is only part of a preferred embodiment of the hosting system.
B. The Broadcaster

16 The Broadcaster module or element tailors a gratuitous ARP packet with specific information: it generates an ARP packet asking "who has the foreign IP address owned by the guest device, tell me".

The MAC address and IP address correspond to the IP address requested by the guest device, whether this be a gateway, a dns, or any other devices the guest device is looking for.

The tailored gratuitous ARP broadcast packet is then transmitted on the network 10.
The packet will be read by all devices on the network, including the guest device 18, causing it to reply to the gratuitous ARP packet and to provide its IP and MAC
information to 1o the hosting system. In doing so, the guest device will make an entry in its ARP table with the new information. Since this new information populates the ARP table of the guest device (ARP table) with an entry IP address entry matching the IP address requested by the guest device, it in turn learns how to speak with its default gateway and allows the guest network device and the hosting system to communicate as if both devices were on the same TCP/IP
subnet.

The broadcaster module includes means 44 for generating and sending the ARP
request.

The main TCP/IP configuration (IP address, subnet mask, default gateway, DNS
servers) of the guest device has not been modified in this process, meaning that there is no need to manually reconfigure the guest device to allow for it to communicate with the hosting system. Advantageously, the packets transmitted from the guest device to the hosting system are not modified either, and no data has been modified. Only if packets are sent to the internet may they be modified by standard Network Address Translation (NAT) methods.

The main TCP/IP configuration (IP address, subnet mask, default gateway, DNS
servers) of the hosting system also has not been modified in this process.

Connections of Main Elements and Sub-Elements of Invention The Listener provides instructions to the Route Builder and the Broadcaster modules.

17 Currently existing alternatives require the creation of ARP reply packets which are sent to a foreign device in reply to its ARP request.

Contrary to available solutions, the hosting system and/or network device of the present invention do not send modified ARP reply packets, but instead only send gratuitous ARP broadcast packets.

One advantage of the present invention over the existing solutions is that the gratuitous ARP packet triggers a change in the ARP table of the guest device by asking the guest device to respond to an ARP request rather than by providing a fake ARP
reply packet, which is subject to be considered as "mangled" packets by anti-virus systems, for example, which are able to prevent standard ARP poisoning techniques resembling existing alternatives.

Another advantage of the present solution is that a validation, in the form of an ARP
response, is received from the guest device at the hosting system, confirming to the hosting system that the new gratuitous ARP packet created and sent by the hosting system has been properly received and learned. Yet another advantage may be that the hosting system's address is broadcast in the gratuitous ARP, and therefore other devices with the same requirement (for example several devices from the same guest, or several guests from the same company) will also be informed of the hosting gateway.

Referring now to Figure 6, an example of a network trace in a network including a guest/client device and a hosting device is shown. The guest device has MAC
address of 00:22:00:99:88; a static IP address of 192.168.10.10 and a subnet of 255.255.255Ø It is statically configured for a default gateway of 192.168.10.2.

The hosting device has LAN MAC address set to 00:10:18:cO:d4:be and is on the same physical network segment as the guest device. The hosting device has a static IP address of 172.168.40.1 and a subnet of 255.255.255.0, the hosting device being on a different subnet than the subnet of the guest device. There are no other devices connected to the same physical network segment, and one object of the hosting device is to provide Internet access to devices connected to its LAN port by providing NAT (Network-Address Translation) towards its WAN
port. Typically, a client configured for DHCP would simply receive an IP
configuration in the

18 172.168.40.xxx network scope, allowing it to use this device as its default gateway/router and access the Internet, much like any common router with DHCP will do.

In this case, since the static configuration on the guest/client device does not match the subnet of the gateway device, the client device would normally not be able to access the Internet. Figure 6 represents a trace of the specific network activity, allowing the hosting device to detect this network situation and modify the MAC device table of the guest device to allow the necessary network routing to take place, and ultimately provide Internet access to the client device.

Still referring to Figure 6, and more specifically to line 1 of the table, the guest device sends an ARP request asking for the MAC address of its statically configured default gateway:
Tell me who has 192.168.10.2. Then, as per the second line of the table, the hosting system does not respond to the initial request and instead responds only with a gratuitous ARP packet:
Tell 192.168.10.2 who has 192.168.10.10. Finally, as per line 3, the guest device responds that 192.168.10.10 [itself] is at 00:22:00:99:99:88. This is no longer a broadcast packet because in step 2, the client device saw that the source was 00:10:18:cO:d4:be. During the process of providing the answer, the client device automatically registers in its MAC
address table that 192.168.10.2 is at 00:10:18:cO:d4:be without having to be told that information with a specific separate ARP message.

It is worth noting that the table below is not a complete network trace but highlights the important packets necessary to demonstrate the main operation of the hosting system.

It is becoming more common for hosting systems of the kind described here to handle more than one network interface, in particular interfaces that are segmented via VLANs. An embodiment of the invention in this environment necessitates additional steps.
When multiple interfaces 24a, 24b etc. are present, they may be actual network interfaces, residing on microchips or on add-in cards, but they may also be virtual interfaces, dummy interfaces, or VLANs, or any similar incarnation of network interfaces.

With reference to Figure 7 and 8, in the case of multiple interfaces, the invention is extended by providing a complete set of modules 26, 28, 30 for each interface 24, so that if there are 4 (four) interfaces, there will be 4 listeners, four broadcasters, and 4 route builders, as if there were four separate hosting systems. The initial transactions with a guest device 18 that

19 has a fixed ip address are identical to the embodiments described above.
However, additional steps are required if the guest device 18 is moved from one local area network interface 24a to another 24b. In this case, the guest device's gateway address may no longer be valid.

An additional module is required, being a storage module 50 where each of the individual broadcasters and route builders record their hosting gateways and routes. In the case of multiple interfaces 24a, 24b, etc, therefore, each of the broadcasters and route builders take the additional step of recording their respective information in the storage module. The storage module 50 provides a single instance of common storage, wherein each instance of broadcaster and builder sees exactly the same information.

The storage module 50 can provide storage which is stored in a variety of mediums, for example, host memory, flash memory, disk storage, even remote storage, as long as this memory is easily and rapidly accessible. The storage provided by the storage module 50 need not be persistent, with respect to the hosting device. If the hosting device is restarted or re-initialized, the storage may also be re-initialized, although this is not necessary.

In addition to storing each guest device's hosting gateway and routing table entry, the storage module also stores a timestamp for each entry. This timestamp is updated each time an entry in the storage module is updated or confirmed.

The additional steps required to accommodate multiple interfaces are the following: In addition to any of the embodiments discussed earlier:

- Once a listener 26 has determined a request from a guest is a compatible ARP
request, - The storage module 50 is queried for the guest device's hardware address, to determine if any previous activity has resulted in a hosting gateway and a route table entry - If not, this embodiment proceeds through the normal steps, but as a last step, provides the storage module 50 with the hosting gateway and routing information generated - If yes, then ^ The broadcaster module 28 determines whether the new required hosting gateway is different from that retrieved from the storage module, = If not, the broadcaster 28 continues to broadcast the previous hosting gateway, and requests the storage module to update its 5 time stamp, to confirm the hosting gateway validity = If so, the broadcaster 28 must broadcast the new hosting gateway and replace the hosting gateway in the storage module for the guest device, which also updates the timestamp.

^ The route builder module 30 determines whether the new required route 10 is different from that retrieved from the storage module, = If not, the route builder 30 rebuilds the route only if the route does not already exist, and requests the storage module update its time stamp, to confirm the guest device's route validity = If so, the route builder 30 must remove the old route before is building the new route, and subsequently update the storage module, replacing the old route with the new route, which also updates the time stamp.

Since multiple interfaces are involved, it may become necessary under certain

20 circumstances to expire certain routes. With the addition of a storage module, an additional module may be used to perform this task:
The cleanup module 52 periodically queries the storage module for stale entries, defined as entries that have not been updated in a pre-determined time. It may also query the hosting system to determine if a guest device considered stale has had any recent network activity, recent being within a time frame defined by the cleanup module.
If a guest device is determined to be stale, the cleanup module may remove any hosting gateway entries, as well as request that the route builder remove existing routes. Any entries in the storage module for the guest device are then removed.
If necessary, during a hosting device restart, for example, the cleanup module can request the storage module to flush all entries.

21 If the guest device then subsequently re-initiates network access, the process begins anew, as though this guest device had never been seen before.
Generally stated, each listener/broadcaster/route builder is tied to a single interface. Guest devices may move from one interface to another, invalidating currently active hosting gateway associations and routes. When this happens, the invalidated gateway associations and routes must be replaced with the proper entries for the new, current interface.
In one embodiment of the invention, the hosting system includes Storage module (single instance) Cleanup module (single instance) In addition to existing modules:
Listener (per interface) Broadcaster (per interface) Route builder (per interface) In this embodiment of the invention, the following additional steps are performed :
Listener - none Broadcaster: read guest device entry for gateway from storage module Write guest device entry for gateway in storage module Update timestamp for guest device entry for gateway in storage module Route builder: read guest device entry for route from storage module Write guest device entry for route in storage module Update timestamp for guest device entry route in storage module Remove invalid route Storage module: Store guest device gateway Store guest device route Store guest device gateway timestamp Store guest device route timestamp Update guest device gateway timestamp Update guest device route timestamp Remove guest device gateway entry Remove guest device route entry

22 Flush all entries Cleanup module: Identify stale guest devices Confirm (checking network use) stale guest devices Remove stale guest devices via storage module Remove stale routes via route builder What has been described and illustrated herein is a preferred embodiment of the invention along with some of its variations. The terms, descriptions, and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the invention in which all terms are meant in their broadest, reasonable sense unless otherwise indicated.

Claims (21)

1. A method performed by a hosting system, to allow a guest device to communicate with a network via the hosting system, the guest device having a static IP address and a guest hardware address, said guest device being configured to communicate through a guest gateway having a guest gateway IP address and a guest gateway hardware address, the hosting system including a hosting gateway having at least one interface provided with a hosting gateway IP address and a hosting gateway hardware address, said hosting gateway IP address being different than said guest gateway IP address, the method comprising the following steps:

a) listening for ARP requests;

b) detecting from said ARP requests a first ARP request from the guest device, requesting the guest gateway hardware address corresponding to the guest gateway IP address, said first ARP request including:

- the guest device IP address;

- the guest gateway IP address; and - the guest device hardware address;

c) upon detection of said first ARP request of step a), broadcasting an ARP
packet including at least:

- the guest gateway IP address; and - the hosting gateway hardware address, wherein destination and source IP addresses correspond to the guest gateway IP address;

said ARP packet triggering in the guest device an update of an ARP table of the guest device, said update consisting of associating the hosting gateway hardware address to the guest gateway IP address; and d) building a route allowing the hosting system to send network packets to the guest device, the method thereby allowing the guest device to communicate with said network via the hosting system.

2. The method according to claim 1, wherein the ARP packet broadcast in step c) is an announcement packet.

3. The method according to claim 2, further including a step of broadcasting a gratuitous ARP
packet, requesting for the guest device hardware address corresponding to the guest device IP address, said gratuitous ARP packet including:

- the guest device IP address;

- the guest gateway IP address; and - the hosting gateway hardware address;
said step being performed after step c).

4. The method according to claim 1, wherein the ARP packet broadcast in step c) is a gratuitous ARP packet, requesting for the guest device hardware address corresponding to the guest device IP address, said gratuitous ARP packet further including:

- the guest device IP address.

5. The method according to claims 3 or 4, comprising a step of receiving at the hosting gateway an ARP response from the guest device, said ARP response including - the guest device IP address;

- the guest device hardware address;
- the hosting gateway IP address; and - the hosting gateway hardware address, said ARP response allowing the hosting gateway to confirm proper update of the ARP
table, said step being performed after step c).

6. The method according to any one of claims 1 to 5, wherein the step of building a route includes generating a first routing table and adding a first route linking the guest device IP address with the hosting gateway IP address of said first interface on which the first ARP request from the guest device was received.

7. The method according to claim 6, comprising a step of associating in a storage module the guest device hardware address with the hosting gateway hardware address of said first interface.

8. The method according to claim 7, comprising a step of monitoring packets received from the guest device, and when said packets are received on a different interface than said first interface, the method further comprises the steps of:

e) broadcasting a second ARP packet including:
- the guest gateway IP address; and - the guest device hardware address;

f) updating the storage module by associating said different interface of the hosting gateway with the guest gateway.

9. The method according to claim 8, comprising the steps of :
g) deleting the first route from said routing table; and h) adding a second route in said routing table linking the guest device IP
address with an IP address of said different interface of the hosting system.

10. The method according to any one of claims 1 to 7, comprising a step of receiving from the guest device a network packet other than an ARP request, the network packet including the hosting gateway IP address and the hosting gateway hardware address.

11. The method according to any one of claims 1 to 8, comprising a step of receiving network packets from other devices external to the network, and exchanging these network packets with said guest device.

12. The method according to any of claims 1 to 9, wherein said steps are performed via a wired or wireless link.

13. A processor-readable storage medium for a hosting system, for allowing a guest device to communicate with a network, the guest device having a static IP address and a guest device hardware address, said guest device being configured to communicate through a guest gateway provided with a guest gateway IP address and a guest gateway hardware address, the hosting system including a hosting gateway having at least one interface provided with a hosting gateway IP address and a hosting gateway hardware address, said hosting gateway IP address being different than said guest gateway IP address, the processor-readable storage medium comprising instructions for execution by the processor to:

- listen to ARP requests, - detect from said ARP requests a first ARP request from the guest device, requesting the guest gateway hardware address corresponding to the guest gateway IP address, said first ARP request including:

- the guest device IP address;

- the guest gateway IP address; and - a guest device hardware address;

- instruct of a detection of the first ARP packet; and generate and broadcast an ARP packet, including:
~ the guest gateway IP address; and ~ the hosting gateway hardware address;

said ARP packet triggering in the guest device an update of an ARP table of the guest device, said update consisting associating hosting gateway hardware address to the guest gateway IP address; and - build a route allowing the hosting system to send network packets to the guest device.

14. The processor-readable storage medium according to claim 13, wherein the ARP packet is an ARP announcement.

15. The processor-readable storage medium according to claim 14, comprising instructions to broadcast a gratuitous ARP packet requesting for the guest device hardware address corresponding to the guest device IP address, said gratuitous ARP packet including:

- the guest device IP address;

- the guest gateway IP address; and - the hosting gateway hardware address.

16. The processor-readable storage medium according to claim 13, wherein the ARP packet is a gratuitous ARP packet, requesting for the guest device hardware address corresponding to the guest device IP address, said gratuitous ARP packet further including:

- the guest device IP address.

17. The processor-readable storage medium according to claim any one of claims 13 to 16, comprising instructions to detect an ARP response from the guest device, said ARP
response including :

- the guest device IP address;

- the guest device hardware address;
- the hosting gateway IP address; and - the hosting gateway hardware address, said ARP response allowing to confirm proper update of the ARP table.

18. The processor-readable storage medium according to claim any one of claims 13 to 17, comprising instructions to:
- monitor packets received from the guest device, and when said packets are received on a different interface than said first interface:
to broadcast a second ARP packet including :
-the guest gateway IP address; and - the guest device hardware address; and - to update a storage module by associating said different interface of the hosting gateway with the guest gateway.

19. A hosting device, for allowing a guest device to communicate with a network, the guest device having a static IP address and a guest device hardware address, the guest device being configured for communicating through a guest gateway provided with a guest gateway IP address and a guest gateway hardware address, the hosting device having a at least one interface provided with a hosting gateway IP address and a hosting gateway hardware address, said hosting gateway IP address being different than said guest gateway IP address, the device comprising:

- a memory;

- a listener module stored in said memory and including:

- listening means for listening to ARP requests, - detecting means for detecting a first ARP request from the guest device, requesting the guest gateway hardware address corresponding to the guest gateway IP address, said first ARP request including:

.cndot. the guest device IP address;

.cndot. the guest gateway IP address; and .cndot. the guest device hardware address;

- instructing means for instructing of a detection of the first ARP packet;
and - a broadcaster module stored in said memory and including means for generating and sending a gratuitous ARP packet, upon being instructed by the instructing means of the detection of the first ARP request, said gratuitous ARP packet asking for the guest device hardware address corresponding to the guest device IP
address, said gratuitous ARP packet including:

- the guest device IP address;

- the guest gateway IP address; and - the hosting gateway hardware address;

- a route builder module, for building a route between said at least one interface and said guest device;

- a processor for executing the listener, the broadcaster and the route builder modules;

the hosting device thereby allowing the guest device to communicate on said network.

20. The hosting device according to claim 19, wherein said at least one interface includes several interfaces each provided with a listener module, a broadcaster module and a route builder module, the hosting device further comprising a storage module including entries associating said guest gateway with one of said several interfaces.

21. The hosting device according to claim 20, further comprising a clean-up module, for querying the storage module and deleting entries which have not been updated after a predetermined amount of time.