Mimic support address resolution

• US 20040098506A1
• Filed: 11/14/2002
• Published: 05/20/2004
• Est. Priority Date: 11/14/2002
• Status: Active Grant

• Current Assignee: Canon Development Americas, Inc. (Canon Inc.)
• Original Assignee: Canon Development Americas, Inc. (Canon Inc.)
• Inventors: Jean, Sebastien A.
• Granted Patent: US 7,756,956 B2
• Time in Patent Office: Days
• US Class Current: 709/245
• CPC Class Codes: H04L 2101/663 Transport layer addresses, e.g. aspects of transmission control protocol [TCP] or user datagram protocol [UDP] ports
• CPC Class Codes: H04L 61/25 of the same type
• CPC Class Codes: H04L 61/255 Maintenance or indexing of mapping tables
• CPC Class Codes: H04L 61/2557 Translation policies or rules
• CPC Class Codes: H04L 61/4541 Directories for service discovery
• CPC Class Codes: H04L 61/4557 Directories for hybrid networks, e.g. including telephone numbers
• CPC Class Codes: H04L 61/5014 using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
• CPC Class Codes: H04L 61/5092 by self-assignment, e.g. picking addresses at random and testing if they are already in use
• CPC Class Codes: H04L 67/563 Data redirection of data network streams
• CPC Class Codes: H04L 67/59 Providing operational support to end devices by off-loading in the network or by emulation, e.g. when they are unavailable
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

Mimicking network devices with a computing device having first and second network interface cards, the first network interface card connecting the computing device to an external network and the second network interface card connecting the computing device to a local network, including obtaining an IP address of a device on the local network, determining an IP address for the second network interface card based on the obtained IP address of the device on the local network, and assigning the determined IP address to the second network interface card.

Claims

1. A method for mimicking network devices, the method being performed in a computing device having first and second network interface cards, the first network interface card connecting the computing device to an external network and the second network interface card connecting the computing device to a local network, the method comprising the steps of:

obtaining an IP address of a device on the local network;

determining an IP address for the second network interface card based on the obtained IP address of the device on the local network; and

assigning the determined IP address to the second network interface card.

2. A method according to claim 1, wherein the IP address for the second network interface card is determined by subtracting one address from the obtained IP address of the device on the local network.

3. A method according to claim 1, further including the steps of:

tracking a legacy source port identifier in a message from a legacy network device on the local network, the message having a destination IP address equal to the assigned IP address of the second network interface card;

obtaining a new source port identifier;

creating a first mapping rule which corresponds to the legacy network device and which maps the legacy source port identifier to the new source port identifier; and

creating a second mapping rule which corresponds to the legacy network device and which maps the new source port identifier to the legacy source port identifier.

4. A method according to claim 3,

wherein the first mapping rule is subsequently applied to each message detected on the local network from the legacy network device which has a destination IP address equal to the assigned IP address of the second network interface card, and which contains the legacy source port identifier, so as to replace the legacy source port identifier in the message with the new source port identifier, and

wherein the second mapping rule is subsequently applied to each message detected on the external network that has a destination address equal to an address of the legacy network device and that contains the new source port identifier, so as to replace the new source port identifier in the message with the legacy source port identifier.

5. A method according to claim 1, further including the steps of:

tracking a legacy source port identifier in a message from a legacy network device on the local network, the message having a destination IP address equal to the assigned IP address of the second network interface card;

determining if the legacy source port identifier corresponds to an application executing on the computing device; and

creating, in the case that the legacy source port identifier does not correspond to an application executing on the computing device, a first mapping rule and a second mapping rule,

wherein the first mapping rule corresponds to the legacy network device and maps the legacy source port identifier to the new source port identifier, and

wherein the second mapping rule corresponds to the legacy network device and maps the new source port identifier to the legacy source port identifier.

6. A method according to claim 5,

wherein the first mapping rule is subsequently applied to each message detected on the local network from the legacy network device which has a destination IP address equal to the assigned IP address of the second network interface card, and which contains the legacy source port identifier, so as to replace the legacy source port identifier in the message with the new source port identifier, and

wherein the second mapping rule is subsequently applied to each message detected on the external network that has a destination address equal to an address of the legacy network device and that contains the new source port identifier, so as to replace the new source port identifier in the message with the legacy source port identifier.

7. A method according to claim 3,

wherein the new source port identifier is obtained from an operating system executing on the computing device.

8. A method according to claim 1, wherein the IP address of the device on the local network is obtained by passively monitoring messages on the local network.

9. A method according to claim 1, wherein the IP address of the device on the external network is obtained in response to a discovery query message issued on the external network by the computing device.

10. A method according to claim 3, further comprising the steps of:

entering the first mapping rule in a local mapping rule table; and

entering the second mapping rule in an external mapping rule table.

11. A method according to claim 1, further including the steps of:

detecting a message from a host device on the external network which has a source IP address equal to the assigned IP address of the second network interface card;

obtaining an initial source port identifier contained in the detected message;

obtaining a new source port identifier;

creating a first mapping rule which corresponds to the host device and which maps the initial source port identifier to the new source port identifier; and

creating a second mapping rule which corresponds to the host device and which maps the new source port identifier to the initial source port identifier.

12. A method according to claim 11,

wherein the first mapping rule is subsequently applied to each message detected on the external network that has a source address equal to that of the host device and that contains the initial source port identifier, so as to replace the initial source port identifier in the message with the new source port identifier, and

wherein the second mapping rule is subsequently applied to each message detected on the local network from the legacy network device which has a destination IP address equal to the assigned IP address of the second network interface card, and which contains the new source port identifier, so as to replace the new source port identifier in the message with the initial source port identifier.

13. A method according to claim 11,

wherein the new source port identifier is obtained from an operating system executing on the computing device.

14. A method according to claim 11, further comprising the steps of:

entering the first mapping rule in an external mapping rule table; and

entering the second mapping rule in a local mapping rule table.

19. A computing device for mimicking network devices, the computing device having first and second network interface cards, the first network interface card connecting the computing device to an external network and the second network interface card connecting the computing device to a local network, said computing device comprising:

a program memory for storing process steps executable to perform a method according to any of claims 1 to 18; and

a processor for executing the process steps stored in said program memory.

20. Computer-executable process steps stored on a computer readable medium, said computer-executable process steps for mimicking network devices and for being performed in a computing device having first and second network interface cards, the first network interface card connecting the computing device to an external network and the second network interface card connecting the computing device to a local network, said computer-executable process steps comprising process steps executable to perform a method according to any of claims 1 to 18.

21. A computer-readable medium which stores computer-executable process steps, the computer-executable process steps to mimic network devices and to be performed in a computing device having first and second network interface cards, the first network interface card connecting the computing device to an external network and the second network interface card connecting the computing device to a local network, said computer-executable process steps comprising process steps executable to perform a method according to any of claims 1 to 18.

15. A method for mimicking network devices, the method being performed in a computing device having first and second network interface cards, the first network interface card connecting the computing device to an external network and the second network interface card connecting the computing device to a local network, the method comprising the steps of:

accessing a list of port identifiers corresponding to ports that are to be blocked;

creating a gate rule for each port identifier in the accessed list, each gate rule for blocking an incoming message from the external network or the local network which contains the corresponding port identifier from being redirected to one of a plurality of applications hosted in the computing device;

tracking a port identifier of a port opened by one of the plurality of applications;

determining if the port identifier of the opened port is equal to a port identifier in a gate rule; and

accessing, in the case that the port identifier of the opened port is equal to a port identifier of a gate rule, the gate rule and modifying the gate rule from a blocking rule to a redirect rule for redirecting an incoming message from the external network or the local network which contains the port identifier of the opened port to the application which opened the port.

16. A method according to claim 15, further comprising the step of:

monitoring for a closing of the port opened by the application; and

accessing, in the case that the port opened by the application is closed, the gate rule having a port identifier equal to the port identifier of the opened port, and modifying the gate rule back from a redirect rule to a blocking rule.

17. A method according to claim 15, further comprising the step of:

creating, in the case that the port identifier of the opened port is not equal to a port identifier of a gate rule, a redirect rule for redirecting an incoming message from the external network or the local network which contains the port identifier of the opened port to the application which opened the port.

18. A method for mimicking network devices, the method being performed in a computing device having first and second net-work interface cards, the first network interface card connecting the computing device to an external network and the second network interface card connecting the computing device to a local network, the method comprising the steps of:

entering a transition state;

enabling a block for incoming messages on the external network and on the local network so as to prevent said messages from being passed through the computing device or responded to by the computing device for a predetermined period of time;

entering an active operational state; and

removing the block for incoming messages on the external network and on the local network so as to allow said messages to be passed through the computing device or responded to by the computing device.