Relayed network address translator (NAT) traversal

• US 20040139227A1
• Filed: 01/15/2003
• Published: 07/15/2004
• Est. Priority Date: 01/15/2003
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Takeda, Yutaka
• Granted Patent: US 7,899,932 B2
• Time in Patent Office: Days
• US Class Current: 709/245
• CPC Class Codes: H04L 61/2567 for reachability, e.g. inquiring the address of a correspondent behind a NAT server
• CPC Class Codes: H04L 61/2575 using address mapping retrieval, e.g. simple traversal of user datagram protocol through session traversal utilities for NAT [STUN]
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 61/5076 Update or notification mechanisms, e.g. DynDNS
• CPC Class Codes: H04L 63/029 Firewall traversal, e.g. tunnelling or, creating pinholes
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]

Abstract

Network Address Translator (NAT) traversal is performed for a host located behind the NAT running a server, e.g., an HTTP server, using a relay server and a redirect server. The host (of the HTTP server) located behind the NAT uses a NAT-discovery process to determine the presence of the interposed NAT. Seamless IP communication over the IP network is provided using a Dynamic DNS (DDNS) system that is updated using a user registration database, which contains information about the presence or absence of a NAT relative to the HTTP server.

Claims

1. A system for communicating over a Network Address Translator (NAT) connected to an Internet Protocol (IP) network there being a first host connected via the NAT to the IP network and a second host connected to the IP network that seeks to communicate with the first host, the system comprising:

at least one relay server connected to the IP network, the relay server being operable as a representative of the first host on the IP network; and

at least one redirect server connected to the IP network;

the redirect server and the relay server being operative, respectively, to cooperatively respond to an access request, which is originated by the second host and targets the first host, by cooperatively facilitating establishment of an IP communication channel between the second host and the first host.

2. The system of claim 1, wherein:

the redirect server is operable to

receive the access message from the second host, and

redirect the access message to a listener operated by the relay server; and

the relay server is operable to relay the access message to the first host.

3. The system of claim 2, wherein the redirect server is operable to redirect the access message to the relay server using at least one of a splash page with a manual redirect, a splash page with an automatic redirect, a protocol based automatic redirect mechanism, and a splash page with a script-based automatic redirect.

4. The system of claim 1, wherein the relay server is operable, prior to receipt of the access request from the second host, to

receive a packet relay request from the first host, and then

provide a listener on behalf of the first host

5. The system of claim 4, wherein the relay server is further operable to provide the first host with an IP address and a port number of the listener.

6. The system for claim 4, wherein

the relay server is a packet relay server, and

the listener is a Transmission Control Protocol (TCP) listener.

7. The system of claim 1, wherein the redirect server is operable to receive an update as to an IP address and a port number of a listener on the relay server corresponding to the first host.

8. The system of claim 7, wherein the update received by the redirect server comes from the first host.

9. The system of claim 1, wherein the relay server is operable to represent an HTTP server being hosted by the first host and the IP communication channel is a Hypertext Transfer Protocol (HTTP) type of connection.

10. The system of claim 1, wherein the IP network is the Internet.

11. An apparatus for seamlessly communicating over an Internet Protocol (IP) network, the apparatus comprising:

at least one Dynamic DNS (DDNS) server; and

a DNS lookup table including a direct transport address for a second host that is directly connected to the IP network and a transport address which a redirect server associates with a first host that is connected via a Network Address Translator (NAT) to the IP network, the DNS lookup table being associated with the DDNS server, the DDNS server resolving a DNS query using the DNS lookup table.

12. The apparatus of claim 11, further comprising:

a user registration database, the DDNS server updating the DNS lookup table after sensing an update to the user registration database.

13. The apparatus of claim 12, further comprising:

a user registrar connected to the user registration database, the user registrar performing online registration of a user to update the registration database; and

an IP registrar connected to the user registration database, the IP registrar updating a transport address of an authenticated user corresponding to one of the first host and the second host.

14. A method for facilitating communication between a client connected to the IP network and a host connected via a Network Address Translator (NAT) to the IP network, the method comprising:

receiving at a relay server connected to the IP network, if a NAT is present in a communication path connecting the host to the IP network, a packet relay request originated by a source server being hosted on the first host;

providing a relay response from the relay server to the source server; and

receiving, at a redirect server, update information originated by the source server based upon the relay response, the update information being usable by the redirect server to facilitate establishment of an IP communication channel between the client and the source server.

15. The method of claim 14, wherein the source server is a Hypertext Transfer Protocol (HTTP) server, the IP network is the Internet, and the IP communication channel is an HTTP type of connection.

16. A method for facilitating communication between a client connected to the IP network and a host connected via a Network Address Translator (NAT) to the IP network, the method comprising:

receiving, at a redirect server, an access request from a second host;

forwarding the access request to a relay server; and

transferring the access request from the relay server to a first host;

the receiving, forwarding and transferring collectively facilitating the establishment of an IP communication channel between the first host and the second host.

17. The method of claim 16, wherein the access request is an HTTP request the IP communication channel is an HTTP connection, an HTTP server is being hosted on the first host and the second host is an HTTP client of the HTTP server.

18. The method of claim 17, wherein the establishment of the IP communication channel includes:

receiving an HTTP response from the HTTP server on the first host at the relay server; and

transmitting the HTTP response from the relay server to the second host.

19. A method for seamlessly communicating over an Internet Protocol (IP) network, the method comprising:

receiving a DNS query from an HTTP client to a DDNS server;

resolving the DNS query using at least one DDNS server having a DNS lookup table, wherein the DNS lookup table includes a direct transport address for a second host that is directly connected to the IP network and a transport address which a redirect server associates with a first host that is connected via a Network Address Translator (NAT) to the IP network; and

generating a DNS response, wherein the DNS response using at least one of the direct transport address and the redirect server'"'"'s address based upon the DNS query being directed to at least one of the first host and the second host, respectively.

20. The method of claim 19, further comprising:

updating the DNS lookup table with information from a user registration database, the user registration database including transport addresses and NAT indicators for indicating presence of NATs for hosts similar to the second host.

21. The method of claim 20, further comprising:

registering a user connected to the user registration database through a user registrar; and

authenticating an IP update from the user using an IP registrar; and

updating the user registration database with a transport address of an authenticated user, the transport address corresponding to at least one of the first host and the second host.

22. A method for facilitating communication from a client connected to the IP network to a host connected via a Network Address Translator (NAT) to the IP network, the method comprising:

receiving a packet relay request at a packet relay server connected to the IP network, the request coming from the host connected via the NAT to the IP network; and

providing a response from the relay server via the NAT to the host that indicates establishment of listener on the relay server that will listen on behalf of the host for communication from the client to the host.

23. The method of claim 22, wherein the host is operable for hosting an HTTP server.

24. The method of claim 22, wherein the listener is a Transmission Control Protocol (TCP) listener.

25. The method of claim 22, wherein the IP network is the Internet.

26. A packet relay server, connected to an Internet Protocol (IP) network, for facilitating communication from a client connected to the IP network to a host connected via a Network Address Translator (NAT) to the IP network, the apparatus comprising:

an input unit to receive a packet relay request coming from the host connected via the NAT to the IP network; and

a processor unit operable to

generate a listener that will listen on behalf of the host for communication from the client to the host, and

provide a response via the NAT to the host that indicates in IP address and port number of listener.

27. The packet relay server of claim 26, wherein an application hosted by the host, for which the listener is generated, is an HTTP server.

28. The packet relay server of claim 26, wherein the listener is a Transmission Control Protocol (TCP) listener.

29. The packet relay server of claim 26, wherein the IP network is the Internet.