KR20070061377A - Apparatus for network address translation for exchanging sip transactions between private network and public network and method thereof - Google Patents

Abstract

A network address translation apparatus and method for exchanging an SIP(Session Initiation Protocol) transaction between a private network and a public network are provided to solve a problem of the related art that an SIP transaction can hardly pass through a network address translation apparatus, so it is not possible for a basic SIP protocol to pass through the network address translation apparatus to normally transmit/receive the SIP transaction. An SIP port(100) receives an SIP message transmitted between an SIP user agent of a private network and a public network and a response message to the SIP message. An address translation unit(110) changes an address for receiving the SIP message included in the SIP message received from the private network to an address of the public network corresponding to the stored address, or a destination address of an SIP message transmitted from the public network to the private network to a corresponding address of the private network.

Description

Apparatus for network address translation for exchanging SIP transactions between private network and public network and method

1 is a diagram showing an operation model according to the present invention.

2 is a diagram illustrating a procedure of transmitting a message to a public network through a SIP addressing agent located in a private network.

3 is a diagram illustrating a procedure for receiving a message from a public network by a SIP user agent located in a private network.

Network Address Translation (NAT) is a technology that maps the IP address area of an IP layer to another IP address area. It is used to provide communication between hosts located in different IP address areas.

Many IP applications cannot communicate through network address translators because network address translation technology only maps address ranges by considering IP header addresses. For example, IP applications that use IP addresses directly as Content or that have different Control Sessions and Data Sessions, such as FTP, are virtually impossible to traverse a network address translation device.

Session Initiation Protocol (SIP) is a transaction-oriented protocol. Interaction between SIP components occurs through a series of independent transaction exchanges. SIP transaction is divided into INVITE transaction and NON-INVITE transaction according to the method of request message that creates transaction.

Each transaction consists of one request message, zero or more provisional response messages, and one final response message for the request message. Exceptionally, for an INVITE transaction, if the final response is not 2xx, an ACK message is included in the INVITE transaction.

When sending a request message and receiving a response message, it is called a client transaction. When receiving a request message and sending a response message, it is called a server transaction. Client transactions are sent in the request message to the Route header address or Request-URI address, and server transactions are sent to the first Via header address in the response message.

The SIP protocol is a protocol for establishing a session. Establishes a session through INVITE transaction exchange. When the session is established, logical information called Dialog is created. The dialog includes information called a remote target, which is used as a Request-URI of a SIP request message after a session is established.

Since fully qualified domain names (FQDNs) or Numeric IP addresses are used for the Route header address, Request-URI address, and Via header address, it is very difficult for SIP transactions to pass through the network address translator and eventually the default SIP protocol is the network address. There is a problem that it is impossible to send and receive SIP transactions normally through the conversion apparatus.

The technical problem to be achieved by the present invention is a network for SIP transaction exchange between a private network and a public network, which enables normal SIP transaction transmission and reception by smoothly passing a SIP transaction through a network address translation apparatus as described above. An address translation apparatus and an address translation method thereof are provided.

In accordance with an aspect of the present invention, a network address translation apparatus for exchanging SIP transactions between a private network and a public network is provided. The SIP address transmitted between a SIP user agent and a public network in the private network and the SIP message are transmitted to the SIP network. A SIP port for receiving a response message; And changing an address for receiving a SIP message included in a SIP message received from the private network to an address in the public network corresponding to the stored address, or replacing a destination address of a SIP message transmitted from the public network to the private network. And an address translation unit for changing the address of the corresponding private network.

At this time, the temporary storage unit for temporarily storing the received SIP message; An address storage unit for storing an address included in each SIP message and an address in the public network corresponding thereto; And a SIP message transmitter for transmitting the changed SIP message to a corresponding address in a public network or to a private network.

In accordance with another aspect of the present invention, there is provided a network address translation method for exchanging SIP transactions between a private network and a public network, the method including: (a) receiving a SIP request message from a SIP user agent in a private network; (b) changing an address for receiving a SIP message included in the received SIP request message into an address in the public network corresponding to the address; And (c) transmitting the changed SIP request message into the public network corresponding to the changed address.

(D) receiving a response message if there is a response message to the request message; And (e) changing the address of the received message to an address in the private network corresponding thereto and transmitting the address to the private network.

Another aspect of the network address translation method for exchanging SIP transactions between a private network and a public network, according to the present invention for solving the above other technical problem, includes: (a) receiving a SIP request message directed to a private network from a resource in the public network; ; (b) changing an address for receiving a SIP message included in the received SIP request message into an address in the private network corresponding to the address; And (c) transmitting the changed SIP request message to the private network corresponding to the changed address.

(D) receiving a response message if there is a response message to the request message; And (e) changing the address of the received response message to an address in the authorized network corresponding thereto and transmitting the address to the authorized network.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates an example of a configuration of a network address translation apparatus for exchanging SIP transactions between a private network and a public network according to the present invention.

The device includes a SIP port 100 for receiving a SIP message transmitted between a SIP user agent and a public network in a private network and a response message for the SIP message, and an address for receiving a SIP message included in a SIP message received from a private network. To the address in the public network corresponding to the stored address, or the address conversion unit 110 for changing the destination address of the SIP message transmitted from the public network to the private network to the address of the private network corresponding thereto, the reception Temporary storage unit 120 for temporarily storing the SIP message, the address storage unit 130, the address stored in each SIP message and the address corresponding to the inside of the authorized network and the changed SIP message in the public network It includes a SIP message transmission unit 140 for transmitting to a corresponding address or a private network.

2 illustrates an example of a flow of a network address translation method for exchanging SIP transactions between a private network and a public network according to the present invention. This method is mainly for the process of transferring SIP message from private network to public network.

Receiving a SIP request message from a Session Initiation Protocol (SIP) user agent in a private network (step 200), and an address corresponding to the address for receiving a SIP message included in the received SIP request message Change to an address in the network (step 210), and transmit the changed SIP request message to the public network corresponding to the changed address (step 220), and if there is a response message to the request message, receive the response message In operation 230, the address of the received message is changed to an address in the private network corresponding thereto and transmitted to the private network, in operation 240.

3 shows an example of a network configuration in which a network address translation apparatus and method according to the present invention are used.

The various user agents 310 connected to the private network 300 transmit SIP messages with the public network 330 through the network address translation apparatus 320 according to the present invention.

The public network 330 is connected to a plurality of SIP domains 360, and each SIP domain is connected to and communicates with the outside through the SIP proxy 340, and may include a SIP registrar 350.

The SIP request message is delivered, for example, from the SIP user agent 310 through the SIP address of the corresponding SIP domain through the network address translation apparatus 320 according to the present invention. In other words, when delivered to the SIP proxy, the subsequent procedure is performed by the SIP proxy, and thus the description of the present invention proceeds as the SIP message delivery starts up to or from the SIP proxy.

4A illustrates a process in which a SIP request message from a SIP user agent 410 is delivered to a SIP proxy 430 in charge of Domain 1 of a public network through a network address translation device 420 according to the present invention. 4B illustrates an example in which a SIP request message delivered according to the process is converted according to the present invention, and FIG. 4C illustrates an example of connection information stored in the network address translation apparatus according to the present invention. It is shown.

4A shows that a SIP user agent 410 in a private network passes a network address translation device 420 to send a REQUEST message (F1, F2 REQUEST) to a SIP proxy server 430 in a public network, respectively, in response. A message delivery process for receiving F3 and F4 REQUEST messages is shown.

In FIG. 4A, the information described in 'SIP user agent information' at 410, 'network address translation device information' at 420, and 'proxies in charge of domain1' at 430 may include SIP user agent 410, network address translation device 420, and the like. Information regarding an IP, a SIP message reception port, and the like that each of the SIP proxy servers 430 has.

FIG. 4B is a diagram illustrating how a SIP message is converted in the message delivery process illustrated in FIG. 4A, and illustrates only a portion of the SIP message related to message routing.

F1 REQUEST is a message sent by the SIP user agent 410 located in the private network, and the private IP address is included in the SIP message. If this message is sent to the SIP proxy 430 located in the public network as it is, the SIP proxy cannot transmit the response message.

F2 REQUEST shows the SIP message after passing through the network address translation device 420. The matters related to routing are changed to the address at which the network address translation apparatus 420 receives the SIP message and transmitted to the SIP proxy 430.

F3 RESPONSE is a response message sent by the SIP proxy 430. Since the SIP response message is created based on the request message, the information such as the Via header is set as the address of the network address translator. If the message is delivered to the SIP user agent 430 in the private network as it is, the SIP user agent cannot recognize this as a response message to the F1 REQUEST. For this reason, the network address translation apparatus 420 changes the F3 RESPONSE to the same form as the F4 RESPONSE.

The following description proceeds according to the configuration and flow shown in FIGS.

When the SIP request message is transmitted from the SIP user agent 310 located in the private network 300 to the network address translation apparatus 320 according to the present invention, the request message is transmitted to the temporary storage unit 120 through the SIP port 100. Temporarily stored (step 200).

At this time, the transmitted SIP request message is F1 REQUEST of FIG. 4A, and the message includes SIP user agent information. The SIP user agent information includes information about IP, SIP listening port and SIP URL as shown in FIG. 4A.

An example of the contents of the SIP request message is described in F1 REQUEST of FIG. 4B.

The address conversion unit 110 changes the address included in the temporarily stored SIP message to an address to which the SIP message can be sent to a place located in the public network (step 210).

In this case, the address may be changed by referring to an address included in each SIP message stored in the address storage unit 130 and an address inside the corresponding authorized network.

In addition, the address can be changed based only on the information contained within the SIP message. To this end, when the address translation unit 110 receives the SIP request message in step 100, it is preferable to determine the Via header address of the SIP request message as a destination address of the SIP message for receiving the SIP message in step 110.

Alternatively, when the address conversion unit 110 receives the SIP request message in step 100, it is preferable to determine the contact header address of the SIP request message as a destination address of the SIP message for receiving the SIP message in step 110.

Since the SIP request message such as INVITE, SUBSCRIBE, REGISTER, etc. may include information to receive the SIP message in the contact header, the address is stored as a forwarding address when the forwarding SIP message has a contact header.

As described above, the SIP request message whose address to which the SIP message is to be delivered is changed is transmitted to the corresponding domain 1 through the SIP message transmitter 140 (step 220). At this time, the SIP request message is delivered to the proxy 430 that is in charge of domain 1 as described above.

This process is F2 REQUEST of FIG. 4A, and FIG. 4B describes an example of SIP request message content that is changed according to the present invention before the F2 REQUEST process and is delivered through F2 REQUEST.

In response to this request message, a response message is sent as a response message through the proxy 430 in domain 1. This response message is F3 RESPONSE in FIG. 4A, and an example of the content of the response message transmitted through the F3 RESPONSE process is illustrated in FIG. 4B.

The response message may be transmitted through the SIP port 100 and temporarily stored in the temporary storage unit 120 (step 210). The address translator 110 changes the address included in the response message to the address of the corresponding private network and transmits the address to the SIP user agent 410 of the corresponding private network through the SIP message transmitter 140 (step 240). In this case, a method similar to that described above may be used.

Figure 4c shows an example of the connection information stored in the network address translation apparatus according to the present invention the SIP message transmission and reception process as described above.

5 illustrates a flow according to the present invention for transmitting a SIP request message from the public network 330 to the private network 300 and receiving a response thereto.

When the SIP port 100 receives a SIP request message destined for a private network from a resource in the public network (step 500), the address conversion unit 110 receives an address for receiving a SIP message included in the received SIP request message. In step 510, the SIP request message with the changed address is transmitted to the private network corresponding to the changed address through the SIP message transmitter 140 (step 520).

If there is a response message to the request message, the SIP port 100 receives the response message (step 530), and the address translator 110 converts the address of the received response message to an address in the public network corresponding thereto. Change to and transmit (step 540).

FIG. 6A illustrates a procedure in which a SIP user agent located in a private network receives a request message from a SIP proxy server located in a public network and transmits a response message thereto. FIG. 6B illustrates a network address translation apparatus according to the present invention. It's about finding a SIP user agent.

The network address translator collects information about the SIP user agent located in the private network in the process of relaying SIP messages transmitted by the SIP user agent located in the private network to the public network and stores the information as shown in the first table of FIG. 6B. do.

FIG. 6A shows a message flow in which a proxy in a state in a public network delivers a message to a SIP user agent in a private network, and the SIP user agent delivers a response message.

The first table of FIG. 6B is information on SIP user agents located in a private network stored internally by the network address translation apparatus. The underlined information is information generated after delivering the F7 RESPONSE information in FIG. 6A, and the underlined information is information obtained in advance about the SIP user agent.

In general, a SIP user agent registers its IP address with the registry when it is first started (using the REGISTER method). The registrar then knows where the Contact Address of a particular SIP URI (eg sip: jupiter@etri.re.kr) is located. The proxy server forwards the SIP message to its Contact Address.

If a Contact Address is not registered in a particular SIP URI, the proxy server does not know where to send the message, so the message is not delivered. In other words, the SIP user agent cannot receive messages through the proxy unless it registers its Contact Address with the registrar (though it is possible for the SIP user agent to send a message).

The information that is not underlined above is previously obtained information, which is information that can be obtained when a user agent transmits a SIP message, such as when registering a contact address with a registrar.

When the network address translator receives the F5 REQUEST, it retrieves the user information (user1, domain1) from the request URI or the To header of the message, and uses it to retrieve information about the SIP user agent in the private network stored by the network address translator. Find and deliver the message.

Figure 6c shows an example of the contents of the SIP message changed through each step according to the present invention, Figure 6d is stored in the network address translation apparatus according to the present invention after delivering the response message sent by the SIP user agent The change in connection information is shown.

FIG. 6C illustrates F5 REQUEST to F8 RESPONSE message information of FIG. 6A. The message information shows only important information related to routing.

F5 REQUEST is a message sent by the proxy in charge of domain1. This message is received by the network address translation device and forwarded to the SIP user agent without changing the message, as can be seen in F6 REQUEST.

F7 RESPONSE message is a response message sent by a SIP user agent located in a private network. The response message may include a contact header. When the network address translator transmits a SIP response message transmitted from the private network to the public network, if the CONTACT header is present in the response message, the network address translator converts the contact information into IP / port information for receiving the SIP message and transmits it. Also, if the transport information obtained from the Via header of the F7 RESPONSE, the username and domain obtained from the To header, and the information corresponding to the type of the converted header are included in the connection information stored in the network address translator, if not, Fig. 6D. Add new connection information as shown in the third record.

When the network address translation apparatus according to the present invention receives the SIP request message from the public network through the SIP port 100, the transport protocol information is extracted from the upper Via header included in the message, and username and domain information from the From header. Extract Based on the extracted information, it finds the type of contact information among the connection information stored in the network address translator and matches the username, domain, and transport protocol information, and delivers the message to the SIP user agent located inside the private network.

In this case, when receiving a SIP response message for the SIP request message in step 530, it is preferable to determine the contact header address of the SIP request message as a destination address of the SIP message for receiving the SIP message in step 540.

That is, in response message for INVITE, SUBSCRIBE, OPTIONS, etc., address that can receive SIP message can be described as Contact header, so if Contact header exists in response message, it is the address to forward the address to inside of message. To save.

Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. Examples included in the above description are introduced for the understanding of the present invention, and these examples do not limit the spirit and scope of the present invention. For example, in the above description, the Internet is mainly used as an example of a communication network, but it is also possible to use a public telephone communication network such as a PSTN, and in addition to the above examples, various embodiments according to the present invention are possible. It will be obvious to those of ordinary skill in this technical field. The scope of the present invention is shown not in the above description but in the claims, and all differences within the scope will be construed as being included in the present invention.

In addition, it can be easily understood by those skilled in the art that each of the above steps according to the present invention can be variously implemented in software or hardware using a general programming technique.

And some steps of the invention may also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, CD-RW, magnetic tape, floppy disks, HDDs, optical disks, magneto-optical storage devices, and carrier wave (eg, Internet It also includes the implementation in the form of). The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

According to the present invention, a SIP message transmitted between a Session Initiation Protocol (SIP) user agent in a private network and a public network and a SIP port for receiving a response message for the SIP message and a SIP message received from a private network are included. An address conversion unit for changing an address for receiving a SIP message to an address in a public network corresponding to the stored address, or for changing a destination address of a SIP message transmitted from the public network to the private network to an address of the private network corresponding thereto; Since the network address translator (NAT) directly inserts an address for sending and receiving SIP messages into the SIP message and relays the SIP message directly, the SIP user agent located in the private network and the SIP user agent located in the public network SIP transactions can be exchanged, making it nearly impossible in the past Is capable of this throw SIP transaction exchange causes the user's convenience improves largely.

Claims (12)

A SIP port for receiving a SIP message transmitted between a Session Initiation Protocol (SIP) user agent in a private network and a public network and a response message for the SIP message; And Change an address for receiving a SIP message included in a SIP message received from the private network to an address in the public network corresponding to the stored address, or correspond to a destination address of a SIP message transmitted from the public network to the private network Address conversion unit for changing to the address of the private network; Network address translation apparatus for the SIP transaction exchange between the private network and the public network. The method of claim 1, A temporary storage unit for temporarily storing the received SIP message; An address storage unit for storing an address included in each SIP message and an address in the public network corresponding thereto; And And a SIP message transmitter for transmitting the changed SIP message to a corresponding address in a public network or to a private network. The method of claim 1, When the address translator receives the SIP request message transmitted by the SIP user agent in the private network to the public network, determining that the Via header address of the SIP request message is the destination address of the SIP message for receiving the SIP message. A network address translation device for SIP transaction exchange between a private network and a public network. The method of claim 1, When the address translation unit receives a SIP request message sent by a SIP user agent in the private network to the public network, determining that the contact header address of the SIP request message is the destination address of the SIP message for receiving the SIP message. A network address translation device for SIP transaction exchange between a private network and a public network. The method of claim 1, When the address translator receives a SIP response message for a SIP request message transmitted from the public network to a SIP user agent in the private network, the contact header address of the SIP request message is transmitted to the SIP message for receiving the SIP message. Network address translation apparatus for the SIP transaction exchange between the private network and the public network, characterized in that determined as the destination address. (a) receiving a SIP request message from a Session Initiation Protocol (SIP) user agent in a private network; (b) changing an address for receiving a SIP message included in the received SIP request message into an address in the public network corresponding to the address; And (c) transmitting the changed SIP request message into a public network corresponding to the changed address, wherein the network address translation method is for exchanging a SIP transaction between a private network and a public network. The method of claim 6, (d) receiving a response message if there is a response message to the request message; (e) changing the address of the received message to an address in the private network corresponding thereto and transmitting the address to the private network; further comprising a network address translation method for a SIP transaction exchange between a private network and a public network. The method according to claim 6 or 7, When the SIP request message is received in step (a), the private network and the public network are determined in step (b) as the destination address of the SIP message for receiving the SIP message. Network address translation method for SIP transaction exchange. The method according to claim 6 or 7, When receiving the SIP request message in the step (a), the private network and the public network, characterized in that in step (b) determines the contact header address of the SIP request message as the destination address of the SIP message for receiving the SIP message Network address translation method for SIP transaction exchange. (a) receiving a SIP request message directed to a private network from a resource in the public network; (b) changing an address for receiving a SIP message included in the received SIP request message into an address in the private network corresponding to the address; And and (c) transmitting the changed SIP request message to a private network corresponding to the changed address. The method of claim 10, (d) receiving a response message if there is a response message to the request message; (e) changing the address of the received response message to an address in the authorized network corresponding thereto and transmitting the address to the authorized network; a network address for SIP transaction exchange between the private network and the authorized network Transformation method. The method of claim 11, In step (d), if the SIP response message is received for the SIP request message, in step (e), the contact header address of the SIP request message is determined as a destination address of the SIP message for receiving the SIP message. Network address translation method for the exchange of SIP transactions between private networks and public networks.

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