System and method for establishing network connection with unknown network and/or user device

• US 7,088,727 B1
• Filed: 10/06/2000
• Issued: 08/08/2006
• Est. Priority Date: 03/12/1997
• Status: Expired due to Term

• Current Assignee: Nomadix, Inc. (Nippon Telegraph and Telephone Corporation)
• Original Assignee: Nomadix, Inc. (Nippon Telegraph and Telephone Corporation)
• Inventors: Kleinrock, Leonard, Short, Joel E.
• Primary Examiner(s): Patel, Ajit
• Application Number:
  US09/684,937
• Time in Patent Office: 2,132 Days
• Field of Search: 370/401, 370/338, 370/389, 370/466, 370/392, 370/229, 370/252, 370/390, 370/393, 370/395, 370/397, 370/400, 370/402, 370/404, 370/406, 370/409, 370/465, 370/467, 370/254, 370/255, 370/408, 709/238, 709/220, 709/228, 709/221, 709/242, 709/230, 709/245, 709/225, 709/222, 709/223, 709/219, 709/226, 709/229
• US Class Current: 370/401
• CPC Class Codes: H04L 41/0813 characterised by the conditions triggering a change of settings
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/10 of different types
• CPC Class Codes: H04L 61/25 of the same type
• CPC Class Codes: H04L 61/5014 using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
• CPC Class Codes: H04L 61/5084 Providing for device mobility network addressing or numbering for mobility support in wireless networks H04W8/26; mobile IP H04W80/04
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 88/182 Network node acting on behalf of an other network entity, e.g. proxy

Abstract

A system and method for connecting a user device to a network where the user device settings, the network settings, or both are unknown include intercepting packets transmitted by the user device and modifying the packets to be compatible with the network. The system and method are particularly suited for use by mobile computers, such as laptop computers, which are connected to various foreign networks. Depending upon the particular application, a device may be carried with the mobile computer, or attached as a node on the network. The device automatically determines the network settings of the user device and/or the network and modifies packets appropriately so that the user device can communicate over the network without having to reconfigure the user device with appropriate settings for each network it may encounter. Communication settings such as network address, gateway, proxy address, etc. are automatically determined using various techniques.

Claims

1. A method for providing connectivity between a foreign device on a second local area network and a user device configured for a first local area network, the user device having a permanent address, the method comprising:

intercepting packets transmitted by the user device intended for the foreign device on the second local area network to automatically determine network settings of the user device, the packets transmitted by the user device having the permanent address of the user device as a source address;

modifying packets transmitted by the user device to make these packets compatible with the second local area network based on the network settings of the user device and on network settings of the second local area network such that the second local area network appears as the first local area network to the user device;

wherein modifying packets transmitted by the user device includes substituting the permanent address of these packets with a router address as the source address, wherein the router address is an address recognized by the foreign device;

intercepting packets transmitted by the foreign device intended for the user device, the packets transmitted by the foreign device having the router address as a destination address;

modifying packets transmitted by the foreign device to make these packets compatible with the first local area network based on the network settings of the user device and on the network settings of the second local area network such that the first local area network appears as the second local area network to the foreign device;

wherein modifying packets transmitted by the foreign device includes substituting the router address of these packets with the permanent address as the destination address.

2. The method of claim 1 wherein the step of intercepting packets transmitted by the user device comprises receiving and processing packets transmitted by the user device which would otherwise be dropped by devices on the second local area network due to incompatible network settings.

3. The method of claim 1 further comprising:

automatically determining the network settings of the second local area network based on packets transmitted over the second local area network.

4. The method of claim 1 further comprising:

automatically determining the network settings of the second local area network by transmitting a Dynamic Host Control Protocol (DHCP) packet over the second local area network.

5. The method of claim 1 wherein the step of intercepting packets transmitted by the user device comprises:

intercepting an Address Resolution Protocol (ARP) message transmitted by the user device having a network address of a device on the first local area network; and

replying to the ARP message with a Media Access Control (MAC) address of a device on the second local area network.

6. The method of claim 1 wherein the step of intercepting packets transmitted by the user device comprises operating in a promiscuous mode to receive and process all packets transmitted by the user device.

7. The method of claim 1 wherein the router address is automatically determined based on the network settings of the second local area network.

8. The method of claim 7 wherein the step of substituting the permanent address of a packet transmitted by the user device comprises replacing a source address within a packet header.

9. The method of claim 7 wherein the step of substituting the permanent address of a packet transmitted by the user device comprises replacing a source address within contents of the packet.

10. The method of claim 1 wherein the step of intercepting packets transmitted by the user device comprises:

intercepting a Dynamic Host Control Protocol (DHCP) packet transmitted by the user device;

determining whether a DHCP server is available on the second local area network; and

replying to the DHCP packet to provide configuration settings based on network settings of the second local area network.

11. A method for providing access to a network utilizing private IP addresses for a user device having an incompatible private IP address, the method comprising:

intercepting data transmitted by the user device containing the incompatible private IP address;

modifying the data using a private IP address compatible with the network private IP addresses; and

transmitting the modified data on the network.

12. The method of claim 11 further comprising connecting a translator to the network to perform the steps of intercepting the data transmitted by the user device, modifying the data, and transmitting the data.

13. The method of claim 12 wherein the step of connecting comprises connecting the translator between the user device and the network.

14. The method of claim 12 wherein the user device and translator are directly connected to the network.

15. The method of claim 11 wherein the step of intercepting packets comprises receiving and processing packets which would otherwise be dropped by devices on the second local area network due to incompatible network settings.

16. The method of claim 11 wherein the step of intercepting packets comprises operating in a promiscuous mode to receive and process all packets transmitted by the user device.

17. The method of claim 11 wherein the step of intercepting packets comprises:

intercepting an Address Resolution Protocol (ARP) message transmitted by the user device; and

replying to the ARP message with a hardware address of a device on the network so future messages transmitted by the user device are directed to the device on the network.

18. A method for providing access to a network utilizing DHCP for a user device configured with a static IP address, the method comprising:

intercepting packets transmitted by the user device to determine the static IP address;

transmitting a DHCP request on the network to determine at least one available network IP address;

modifying the packets transmitted by the user device based on an available IP address; and

transmitting the modified packets on the network to provide network access to the user device.

19. A method for providing connectivity to a first network for a user device, the user device having a permanent address, the method comprising:

automatically determining network settings of the first network based on addresses contained in messages transmitted over the first network;

intercepting user device messages transmitted over the first network without regard to message destination addresses, the user device messages having the permanent address of the user device as a source address; and

modifying incorrectly configured messages transmitted by the user device based on the network settings of the foreign network, wherein modifying incorrectly configured messages transmitted by the user device includes substituting the permanent address of these messages with a router address as the source address, wherein the router address is an address recognized by the foreign network.

20. The method of claim 19 wherein the user device is configured to communicate over a home network having network settings incompatible with the foreign network, the method further comprising:

automatically determining network settings of the user device by intercepting an Address Resolution Protocol (ARP) message transmitted by the user device having a destination address of a device on the home network and replying to the ARP message by associating a Media Access Control (MAC) address of a device on the first network with the destination address of the device on the home network.