System and method to support networking functions for mobile hosts that access multiple networks

• US 7,441,043 B1
• Filed: 12/31/2002
• Issued: 10/21/2008
• Est. Priority Date: 12/31/2002
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Jiang, Zhimei, Kim, Byoung-Jo J, Leung, Kin K, Luo, Hui, Shankaranarayanan, Nemmara K, Henry, Paul Shala
• Primary Examiner(s): Follansbee, John
• Assistant Examiner(s): Cloud, Joiya M
• Application Number:
  US10/334,628
• Time in Patent Office: 2,121 Days
• Field of Search: 709/238, 455/435.1
• US Class Current: 709/238
• CPC Class Codes: H04L 61/25 of the same type
• CPC Class Codes: H04L 61/2564 for a higher-layer protocol, e.g. for session initiation protocol [SIP]
• CPC Class Codes: H04L 61/2592 using tunnelling or encapsulation
• CPC Class Codes: H04L 63/0272 Virtual private networks
• CPC Class Codes: H04L 63/0815 providing single-sign-on or federations
• CPC Class Codes: H04L 63/164 at the network layer
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
• CPC Class Codes: H04W 12/062 Pre-authentication
• CPC Class Codes: H04W 12/069 using certificates or pre-shared keys
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

An IP-based corporate network architecture and method for providing seamless secure mobile networking across office WLAN, home WLAN, public WLAN, and 2.5G/3G cellular networks for corporate wireless data users. The system includes Internet roaming clients (IRCs), a secure mobility gateway (SMG), optional secure IP access (SIA) gateways, and a virtual single account (VSA) server. The IRC is a special client tool installed on a mobile computer (laptop or PDA) equipped with a WLAN adaptor and a cellular modem. It is responsible for establishing and maintaining a mobile IPsec tunnel between the mobile computer and a corporate intranet. The SMG is a mobile IPsec gateway installed between the corporate intranet and the Internet. It works in conjunction with the IRC to maintain the mobile IPsec tunnel when the mobile computer is connected on the Internet via a home WLAN, a public WLAN, or a cellular network. The SIA gateway is a special IPsec gateway installed in the middle of the wired corporate intranet and an office WLAN. It works with the IRC to ensure data security and efficient use of corporate IP addresses when the mobile computer is connected to the office WLAN. The VSA server manages authentication credentials for every corporate user based on a virtual single account concept. The Internet Roaming system can provide secure, always-on office network connectivity for corporate users no matter where they are located using best available wireless networks.

Claims

1. A method of routing packets between a first network access device connected to the Internet through a first access network, and a second network access device, the method being performed at a secure mobility gateway having at least one Internet interface and at least one intranet interface, comprising the steps of:

receiving an encapsulated IP-in-UDP racket sent from the first network access device to the second network access device through the Internet interface, the IP packet being encrypted;

locating a mobile status record for the first network access device, wherein the mobile status record is located using a Security Association Index number in the encrypted IP-in-UDP packet;

verifying the IP-in-UDP packet based on a parameter contained in the IP-in-UDP packet and, if the parameter is valid, then

updating the mobile status record by replacing a current care-of IP address in the mobile status record with an outer source IP address of the IP-in-UDP packet, replacing a current interface in the mobile status record with the Internet interface if the current interface is the intranet interface for the first network access device, and replacing a packet sequence number for the first network access device in the mobile status record with the packet sequence number of the IP-in-UDP packet for the first network access device, if the packet sequence number of the IP-in-UDP packet is greater than a current packet sequence number stored in the mobile status record;

decapsulating the IP-in-UDP packet;

decrypting the IP packet;

sending the unencrypted IP packet to the second network access device through an Intranet interface, as if the first network access device is deployed on a subnet of an Intranet that is represented by the Intranet interface;

receiving an IP packet sent from the second network access device to the first network access device at the Intranet interface;

locating a mobile status record using the destination IP address as an index;

encrypting the IP packet using the Security Association in the mobile status record;

encapsulating the IP packet into an IP-in-UDP packet; and

sending the encrypted IP-in-UDP packet to the first network access device through the Internet interface.

2. A method of routing packets between a first network access device connected to the Internet through a first access network, and a second network access device, the method being performed at a secure mobility gateway having at least one Internet interface and at least one intranet interface, comprising the steps of:

receiving an encapsulated IP-in-UDP packet sent from the first network access device to the second network access device through the Internet interface, the IP packet being encrypted;

locating a mobile status record for the first network access device;

verifying the IP-in-UDP packet based on a parameter contained in the IP-in-UDP packet and, if the parameter is valid, then

updating the mobile status record by replacing a current care-of IP address in the mobile status record with an outer source IP address of the IP-in-UDP packet, replacing a current interface in the mobile status record with the Internet interface if the current interface is the intranet interface for the first network access device, and replacing a packet sequence number for the first network access device in the mobile status record with a packet sequence number of the IP-in-UDP packet for the first network access device, if the packet sequence number of the IP-in-UDP packet is greater than the packet sequence number stored in the mobile status record;

decapsulating the IP-in-UDP packet;

decrypting the IP packet; and

sending the unencrypted IP packet to the second network access device through an Intranet interface, as if the first network access device is deployed on a subnet of an Intranet that is represented by the Intranet interface, wherein the packet sent from the first network access device to the second network access device has respective source and destination IP addresses IP_MH and IP_DST, and the encapsulated IP-in-UDP packet has respective source and destination IP addresses IP_local and IP_SMG and respective source and destination UDP port numbers UDP_local and 434 respectively, and further wherein the encapsulated IP-in-UDP packet is received from a NAT box that changed the source IP address IP_local to IP_NAPT, and the source UDP port number from UDP_local to a port number UDP_NAPT.

3. The method recited in claim 2, further comprising the steps of:

receiving from the second network access device at the Intranet interface, an IP packet having respective source and destination IP addresses IP_DST and IP_MH;

encrypting and encapsulating the IP packet received from the second network access device into a IP-in-UDP packet having respective source and destination addresses IP_SMG and IP_NAPT and respective source and destination UDP port numbers 434 and UDP_NAPT; and

sending the encapsulated IP-in-UDP packet to the NAT box.

4. A method of routing packets between a first network access device connected to an Intranet through a private access network, and a second network access device, the method being performed at a secure IP access gateway and comprising the steps of:

receiving an encapsulated IP-in-UDP packet sent from the first network access device to the second network access device at a secure IP access gateway disposed between the private access network and the Intranet, the IP packet being encrypted using a session key negotiated between the first network access device and the secure IP access gateway, and the entire IP-in-UDP packet having a message integrity code generated using another session key specified by a Security Association in a mobile status record in a secure mobility gateway;

decrypting the IP packet at the secure IP access gateway, wherein the message integrity code of the IP-in-UDP packet remains unchanged;

sending the encapsulated IP-in-UDP packet to the secure mobility gateway having an Internet interface facing the Internet, and an Intranet interface facing the Intranet;

the IP-in-UDP packet being sent to the Intranet interface;

locating a mobile status record using a Security Association Index number in the IP-in-UDP packet;

verifying the message integrity code of the IP-in-UDP packet based on the Security Association; and

if it is valid, then

updating the mobile status record by replacing a current care-of IP address in the mobile status record with an outer source IP address of the IP-in-UDP packet, replacing a current interface in the mobile status record with the Internet interface if the current interface is the intranet interface for the first network access device, and replacing a packet sequence number for the first network access device in the mobile status record with a packet sequence number of the IP-in-UDP Packet for the first network access device, if the packet sequence number of the IP-in-UDP packet is greater than the packet sequence number stored in the mobile status record;

decapsulating the IP-in-UDP packet at the secure mobility gateway;

sending the unencrypted IP packet to the second network access device through the Intranet interface, as if the first network access device is deployed on a subnet of the Intranet that is represented by the Intranet interface;

receiving an IP packet sent from the second network access device to the first network access device at the Intranet interface of the secure mobility gateway;

locating a mobile status record using the destination IP address as an index;

encapsulating the IP packet into an IP-in-UDP packet with the Security Association Index and a message integrity code at the secure mobility gateway;

sending the IP-in-UDP packet to the first network access device through the Intranet interface; and

encrypting an inner IP packet of the IP-in-UDP packet using a session key negotiated between the first network access device and the secure IP access gateway when it passes the secure IP access gateway;

the encrypted IP-in-UDP packet being sent to the first network access device over the private access network.