JP2006211601A - Address translation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an address conversion device in which external equipment can simultaneously establish sessions with a plurality of LAN side apparatuses using one external port. <P>SOLUTION: An SIP determination section 105 determines whether a received packet is an SIP request packet transmitted from a WAN side or any other SIP packet or is not an SIP packet, and an IP address conversion section 103 rewrites a destination IP address of an IP header according to a URI in a "To" header field included in a payload of the SIP request packet received from a WAN side communication section. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication device that performs communication with a LAN and communication with a WAN, and particularly relates to an address translation device for relaying communication between a LAN side and a WAN side.

  Conventional NAT (RFC2663) is a technique for performing conversion between one global address and at most one local IP address. On the other hand, NAPT (RFC2663) is a technology that enables a single global IP address to be associated with a plurality of local IP addresses by using a port number for identification at the time of address translation. That is, one local IP address and port number correspond to one port number on the WAN side.

  When conventional NAT is used in an application such as VoIP that can start a session from the WAN side to the LAN side, the number of LAN side devices that can simultaneously establish a session from the WAN side is only one. .

On the other hand, when NAPT is used, by registering the relationship between the WAN side port number and the local IP address and port number on the LAN side in advance, if multiple WAN side ports are used, a plurality of A session can be established with the LAN side device.
Japanese Patent Laying-Open No. 2004-70828 (FIG. 1)

  However, when starting a session to the LAN side device, the WAN side device needs to know in advance the WAN side port number for connection to the LAN side device. In addition, since it is necessary to open all WAN ports scheduled for communication, there is a problem in terms of security.

  SUMMARY OF THE INVENTION In order to solve the above-described problems, an object of the present invention is to provide an address translation device that allows an external device to simultaneously establish a session with a plurality of LAN-side devices using a single external port.

  In order to solve the above-described problems, the present invention provides a first communication unit that performs communication with a first network, a second communication unit that performs communication with a second network, and the received packet is the second communication unit. A SIP determination unit for determining whether the packet is a SIP request packet transmitted from the communication unit of the other, a SIP packet other than that, or a SIP packet, and a header for acquiring the designated SIP message-header from the packet The destination IP address of the IP header is determined according to the URI of the To header field included in the payload of the SIP request packet received from the second communication unit, the address conversion table having the field acquisition unit, the URI and the IP address as a pair. And an IP address conversion unit to be rewritten.

  In order to solve the above-described problem, the present invention provides an IP address acquisition unit that acquires a source IP address from the received packet, a method acquisition unit that extracts a method of the SIP packet, and the method is register A translation table registration unit for adding a pair of the source IP address of the SIP packet or the IP address of the Contact header field of the SIP packet and the URI of the To header field of the SIP packet as an IP address to the address translation table; Instead of the IP address conversion unit of the address conversion device, an IP address conversion unit that transfers a packet to the conversion table registration unit when an SIP packet is received from the first communication unit is provided.

  An external device can establish a session with a plurality of LAN side devices simultaneously using one external port.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a system configuration of an address translation apparatus 100 showing an embodiment of the present invention.

  The LAN side communication unit 101 shown in FIG. 1 is a connection port with the private network 102, receives a packet from a device on the private network 102, outputs the packet to the IP address conversion unit 103 of the address conversion device 100, and this address. An operation of transmitting a packet input from the IP address conversion unit 103 of the conversion apparatus 100 to a device on the private network 102 is executed.

  In the present embodiment, an IP address used on the private network 102 on the LAN side is referred to as a local IP address.

  The WAN-side communication unit 104 is a connection port with the Internet. The WAN side communication unit 104 receives a packet from the Internet, outputs the packet to the IP address conversion unit 103 of the address conversion device 100, and transmits the packet input from the IP address conversion unit 103 to the Internet. Perform the operation to send to the above device.

  In the embodiment, an IP address used on the Internet is referred to as a global IP address.

  The SIP determination unit 105 confirms the payload of the input packet and determines whether the packet is a SIP request packet from the WAN side or another SIP packet. If it is neither, it is determined that the packet is not a SIP packet.

  After the determination, the determination result is output to the IP address conversion unit 103. The SIP packet is determined based on whether or not “SIP” is included in the start-line included in the packet payload. Whether the packet is a SIP request packet is determined by whether the destination port number in the IP header of the SIP packet is 5060. The SIP request packet is determined by the 5060 port because the SIP well known port number is 5060, the destination port number of the normal SIP packet is 5060, and the result of transmission from the LAN side is obtained. This is because the destination port number is considered to be other than the 5060th port due to NAPT in the case of the SIP response packet.

  The header field acquisition unit 106 receives the packet and the type of SIP message-header as input, acquires the specified message-header from the packet, and outputs the acquired message-header.

  Here, the above-described SIP packet refers to an IP packet including a SIP message. The SIP message consists of a start-line, a message-header, and a message-body. start-line consists of Status-line or Request-line. Request-line includes a method that represents the type of request.

  Method types include invite for setting up a session, register for registering contact information, and the like. The message-header type includes a To header field containing the logical destination of the SIP message, a From header field containing the logical identity that initiated the SIP request, and a Call- for identifying the SIP dialog. There are an ID, a Contact header field indicating a contact destination of a device that has transmitted the SIP message, and the like. The From header field, To header field, and Contact header field include a URI.

  The SIP request packet refers to a packet for making a request from a WAN side device to a LAN side device among IP packets including a SIP message.

  The address conversion table 107 is a table having a URI and an IP address as a set. FIG. 2 shows an example of this address conversion table. As is apparent from the figure, each URI corresponds to an IP address, and is a table storing a plurality of sets.

  In addition to the NAPT (RFC2663) function and the function of converting the IP address in the SIP message included in the packet payload implemented by the prior art (Japanese Patent Laid-Open No. 2003-174466), the IP address conversion unit 103 When converting a SIP request packet from a global IP address to a local IP address, the SIP request packet has a function of determining a local IP address after conversion by referring to a SIP message-header included in the payload of the SIP request packet.

  Next, a detailed configuration of the IP address conversion unit 103 will be described with reference to FIG. As shown in FIG. 3, the IP address conversion unit 103 includes a NAPT 108, a NAPT conversion table 109, a message rewriting unit 110, an address conversion control unit 111, and an IP header rewriting unit 112 as components.

  The NAPT 108 has a function of converting an address and a port number. Details of the function of NAPT are specifically shown in documents such as RFC2663. If the input packet is a packet from the LAN side, the NAPT 108 converts the source address included in the IP header of the packet from the local IP address to the global IP address, and converts the source port number to an unused port number. To do.

  After the conversion, the converted information is registered in the NAPT conversion table 109. The NAPT conversion table 109 stores information on a pair of a port number after conversion and a local IP address and port number before conversion. After registering information in the NAPT conversion table 109, the converted packet is output to the address conversion control unit 111.

  On the other hand, if the input packet is a packet from the WAN side, the NAPT conversion table is searched with the destination port number included in the IP header of the packet, and the IP header of the IP header is obtained from the IP address and port number obtained as a result of the search. Convert destination address and destination port number. The converted packet is output to the address translation control unit 111. If there is no conversion information in the NAPT conversion table 109, an error is output to the address conversion control unit 111.

  The message rewriting unit 110 has a function of rewriting the message-header and message-body of the SIP packet as disclosed in Japanese Unexamined Patent Application Publication No. 2003-174466. The message rewriting unit 110 accepts the SIP packet and IP address as input, and rewrites the IP address in the message-header and message-body of the input SIP packet with the input IP address. Then, the rewritten SIP packet is output to the address translation control unit 111.

  The IP header rewriting unit 112 receives the IP address and the SIP request packet as inputs, and converts the destination address included in the IP header of the SIP request packet into the input IP address. The converted SIP request packet is output to the address translation control unit 111.

  When a packet is input from the WAN side communication unit 104, the address translation control unit 111 outputs the input packet to the SIP determination unit 105. As a result of the output, if the packet is not a SIP request packet, the IP header is converted by outputting the packet to the NAPT 108. When an error is returned from the NAPT 108, the error is output to the WAN side communication unit 104.

  If the packet is not an SIP packet, the converted packet is output to the LAN side communication unit 101. If it is an SIP packet, the converted packet and the destination IP address converted by the NAPT 108 are output to the message rewriting unit 110, whereby the payload of the SIP packet is rewritten, and the rewritten packet is rewritten to the LAN side communication unit 101. Output to.

  If the result of the SIP determination unit is a SIP request packet, the To request field included in the SIP request packet is obtained by transmitting the SIP request packet and To to the header field acquisition unit 106. The address translation control unit 111 searches the address translation table using the acquired URI of the To header field as a key, and obtains a pair of IP addresses.

  After acquiring the IP address, the IP header rewriting unit 112 rewrites the destination address included in the IP header of the SIP request packet with the acquired IP address. After the rewriting, the rewritten SIP request packet is transmitted to the message rewriting unit 110, whereby the local IP address included in the payload of the SIP request packet is rewritten with the IP address acquired from the address conversion table 107. The rewritten SIP request packet is output to the LAN side communication unit 101.

  When a packet is input from the LAN side to the address conversion control unit 111, the address conversion control unit 11 converts the IP header by outputting the input packet to the NAPT 108. After the conversion, the packet is transmitted to the SIP determination unit 105. If it is a SIP packet, the message rewriting unit 110 converts the local IP address included in the payload of the SIP packet into a global IP address. The address translation control unit 111 outputs the translated packet to the LAN side communication unit 101.

  Next, a processing operation based on the configuration of the IP address conversion unit 103 described above will be described.

  When the packet is input from the WAN side communication unit 104, the IP address conversion unit 103 transmits the input packet to the SIP determination unit 105. When the packet is not a SIP packet as a result of the determination, the IP address conversion unit 103 uses the function of the NAPT 108 to Rewrite the destination address and destination port number. If rewriting fails, an error is transmitted to the WAN side communication unit 104. If successful, the rewritten SIP packet is transmitted to the LAN side communication unit 101.

  If it is determined that the packet is a SIP packet but not a SIP request packet, the destination address and destination port number of the IP header are rewritten by the function of the NAPT 108, and the IP address and message- included in the SIP message-header in the SIP packet Rewrite the IP address included in the body. The converted SIP packet is transmitted to the LAN side communication unit 101 after rewriting.

  As a result of the determination, if it is a SIP request packet, the To header field included in the input packet is acquired by transmitting the SIP request packet and the message-header type To to the header field acquisition unit 106. The SIP To header field includes a URI as a logical destination of the SIP message. The URI (Uniform Resource Identifier) here refers to all URIs used to represent a destination in SIP, such as SIP URI, SIPS URI, and tel URL.

  After acquiring the To header field, the IP address conversion unit 103 acquires an IP address from the address conversion table 107 using the URI included in the To header field as a key. Based on the acquired IP address, the destination address of the IP header of the SIP request packet is converted. The destination port number is not changed. After rewriting, according to the prior art, the IP address included in the SIP message-header and the IP address included in the message-body in the SIP request packet are rewritten with the IP address acquired from the address conversion table 107. The converted SIP request packet is transmitted to the LAN side communication unit 101 after rewriting.

  When a packet is input from the LAN side, the source address and source port number included in the IP header of the packet are rewritten according to the normal operation of the NAPT 108. The rewritten IP address converting unit 103 determines the packet by the SIP determining unit 105, and if the result of the determination is not a SIP packet, transmits the SIP packet to the WAN side communication unit 104. If it is a SIP packet, the SIP message-header and message-body in the SIP packet are transmitted to the rewritten WAN side communication unit 104.

  Next, the embodiment of the present invention based on the above-described configuration will be described more specifically with reference to FIG.

  FIG. 4 shows a state in which the address translation apparatus 100 of this embodiment is connected to the network via the LAN side communication unit and the WAN side communication unit, and SIP UA t1114 is a device connected to the private network. The SIP UA xyz 115 is a device connected to the Internet.

  First, it is assumed that the SIP UA xyz 115 transmits a SIP invite message to the SIP UA t1114 ((1) in FIG. 4). The destination IP address of the SIP request packet to be transmitted is 200.100.0.1, and the port number is 5060, which is a well known port number of SIP. The SIP message-header To header field included in the payload of the SIP packet includes the URI of SIP UA t1 (SIP: t1@in.com).

  In the address translation device 100, the WAN side communication unit 104 receives a packet from the WAN side. When the SIP request packet is input to the WAN side communication unit 104, the WAN side communication unit 104 outputs the input SIP request packet to the IP address conversion unit 103.

  When the SIP determination unit 105 determines that the IP address conversion unit 103 is a SIP request packet, the IP address conversion unit 103 transmits the SIP request packet and the message-header type To to be acquired to the header field acquisition unit 106, and as a result, the SIP request packet The SIP To header field included in the payload is acquired. After acquisition, the address conversion table 107 is searched using the URI (SIP: t1@in.com) included in the acquired To header field as a key, and a paired IP address (192.168.0.1) is acquired.

  Here, it is assumed that a set of URI and IP address is written in the address conversion table 107 in advance. The addition to the address conversion table 107 may be performed by the user by having the user input unit of the device of the present invention. After acquisition, the destination address in the IP header of the SIP request packet is converted from the global IP address (200.100.0.1) to the acquired IP address (192.168.0.1).

  After the conversion, the IP address included in the payload of the SIP request packet is replaced with the IP address obtained from the table, and the replaced SIP request packet is output to the LAN side communication unit 101. The LAN side communication unit 101 transmits the received SIP request packet to the private network. The destination IP address of the SIP request packet to be transmitted is 192.168.0.1 ", and the destination port number is" 5060 "((2) in FIG. 4).

  When the SIP UA t1114 returns a SIP OK message to the SIP UA xyz 115 ((3) in FIG. 4), the LAN side communication unit 101 accepts the SIP packet. The LAN side communication unit 101 transmits the SIP packet to the IP address conversion unit 103. The IP address conversion unit 103 rewrites the source address and source port number of the IP header of the SIP packet by the function of the NAPT 108, and rewrites the payload of the SIP packet by a prior art method. After rewriting, the ISP packet is output to the WAN side communication unit 104. The WAN communication unit transmits the received SIP packet to the Internet ((4) in FIG. 4).

  Next, an example in which SIP UA xyz transmits a SIP invite message to SIP UA t1 and SIP UA t2 at the same time will be described with reference to FIG.

  As described with reference to FIG. 4, the SIP request packet transmitted by the SIP UA t1114 has a destination address of 200.100.0.1 and a destination port number of 5060, and the SIP To header field included in the payload is SIP: t1 @ in .com.

On the other hand, the destination IP address and the port number of the SIP request packet transmitted by the SIP UA t2116 are the same as those of the SIP UA t1114, and the SIP To header field included in the payload is SIP: t2@in.com.

  When receiving the SIP request packet, the address translation apparatus 100 according to the present embodiment refers to the address translation table 107 using the SIP To header field, and distributes the SIP request packet to the corresponding device. Therefore, the destination IP address of the SIP request packet to SIP UA t1114 transmitted from the address translation device 100 is 192.168.0.1, and the destination IP address of the SIP request packet to SIP UA t2 is 192.168.0.2.

  As described above, the address translation device 100 according to the above-described embodiment rewrites the destination IP address of the SIP request packet by using the URI of the To header field included in the payload of the SIP request packet.

  Then, by referring to the payload of the SIP request packet, even when a plurality of devices are connected to the address translation device of this embodiment, the received SIP packet is transferred to the corresponding device on the same WAN side port. Can do. The WAN side device can establish a session with a plurality of devices connected to the invention apparatus.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  In the second embodiment, the description of the same configuration as that of the first embodiment is omitted.

  As shown in FIG. 6, the device configuration shown in the second embodiment includes an IP address acquisition unit 117 in addition to the device configuration of the first embodiment shown in FIG. The IP address acquisition unit 117 acquires the source IP address from the IP header of the input packet, and outputs the acquired source IP address.

  Furthermore, the device configuration of the second embodiment has a method acquisition unit 118 in addition to the device configuration of the first embodiment. When the SIP packet is input, the method acquisition unit 118 acquires a method from the Request-line of the SIP packet and outputs the acquired method.

  Furthermore, the device configuration of the second embodiment has a conversion table registration unit 119 in addition to the device configuration of the first embodiment. The conversion table registration unit 119 acquires the method of the SIP packet from the method acquisition unit 117, and when the method is Register, compares the From header field acquired from the header field acquisition unit 106 and the URI of the To header field.

  If they are the same, it means that the SIP UA that has output the register packet registers itself, so that the IP address acquired from the IP address acquisition unit 117 and the URI of the To header field acquired from the header field acquisition unit 106 Is registered in the address conversion table 107.

  If the From header field and the To header field have different URIs, it means that the SIP UA that has output the register packet registers other SIP UAs. Therefore, the local IP of the Contact header field acquired from the header field acquisition unit 106 is used. A pair consisting of the address and the URI of the To header field acquired from the header field acquisition unit 106 is registered in the address conversion table 107.

  Furthermore, the IP address conversion unit 120 according to the second embodiment transmits a packet to the conversion table registration unit 119 if the received packet is SIP and is a packet from the LAN side. Other processes are the same as those of the IP address conversion unit 103 of the first embodiment.

  Next, a specific operation of the second exemplary embodiment of the present invention will be described with reference to FIG. Note that the same components as those in the subject embodiment will be described using the same reference numerals.

  The SIP UA t2116, which is a device on the private network, outputs a SIP register packet to the register server 121. In the message-header of the SIP packet to be output, the From header field is “t2 <SIP: T2@IN.COM>; tag = 1” and the To header field is “t1 <SIP: T1@IN.COM>”. Yes, the Contact header field is "t1@192.168.0.1". When the IP address conversion unit 119 of the address conversion device 100 receives the SIP UA t2116 packet output from the LAN side communication unit 101, the packet is SIP and received from the LAN side. It transmits to the registration part 119.

  Since the SIP packet method is register, the conversion table registration unit 119 acquires the SIP From header field, To header field, and Contact header field included in the packet payload from the header field acquisition unit 117. After the acquisition, the conversion table registration unit 119 compares the URI of the From header field acquired from the header field acquisition unit (SIP: t2@in.com) and the URI of the To header field (SIP: t1@in.com).

  In the second embodiment, since the URI of the From header field is different from the URI of the To header field, it can be seen that the UA that has output the packet registers another UA (SIP UA t1). Therefore, the conversion table registration unit 119 extracts the local IP address (192.168.0.1) from the Contact header field acquired from the header field acquisition unit 106, and sets the extracted address as a registered address in the address conversion table 107.

What is additionally registered in the address conversion table 107 of the second embodiment is that the To header field (SIP: t1@in.com) acquired from the header field acquisition unit 117 and the IP address (192.168. 0.1).

  Also, SIP UA information registered at the time of registration in the SIP Register server is automatically registered in the address conversion table 107. Thereby, the load of registering the address translation table of the user is reduced.

  As described above, according to the second embodiment, the destination IP address of the SIP request packet is rewritten using the URI of the To header field included in the payload of the SIP request packet. Further, by referring to the payload of the SIP request packet, even when a plurality of devices are connected to the address translation device 100, the received SIP packet to the same WAN side port can be transferred to the corresponding device. The WAN side device can establish a session with a plurality of devices connected to the invention apparatus.

  In addition, SIP UA information registered at the time of registration with the SIP Register server is automatically registered in the address conversion table. Thereby, the load of registering the address translation table of the user is reduced.

It is a system configuration figure showing a 1st embodiment of the present invention. It is a figure which shows an example of the address conversion table in the embodiment. It is the figure which showed the IP address conversion part in the same embodiment in detail. It is a figure for demonstrating the operation | movement in the embodiment. It is a figure for demonstrating the operation | movement in the embodiment. It is a system configuration figure showing a 2nd embodiment of the present invention. It is a figure for demonstrating the operation | movement in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Address conversion apparatus, 101 ... LAN side communication part, 103 ... IP address conversion part, 104 ... WAN side communication part, 105 ... SIP determination part, 106 ... Header field acquisition part, 107 ... Address conversion table.

Claims (4)

A first communication unit that communicates with the first network;
A second communication unit for communicating with the second network;
A SIP determination unit for determining whether the received packet is a SIP request packet transmitted from the second communication unit, a SIP packet other than that, or a SIP packet;
A header field acquisition unit for acquiring a specified SIP message-header from a packet;
An address translation table having a URI and an IP address as a set;
An IP address conversion unit for rewriting the destination IP address of the IP header according to the URI of the To header field included in the payload of the SIP request packet received from the second communication unit;
An address translation device comprising: An IP address acquisition unit for acquiring a source IP address from the received packet;
A method acquisition unit for extracting a method of the SIP packet;
When the method is register, the source IP address of the SIP packet as the IP address or the IP address of the Contact header field of the SIP packet;
A translation table registration unit for adding a pair with the URI of the To header field of the SIP packet to the address translation table;
An IP address conversion unit that transfers a packet to the conversion table registration unit when a SIP packet is received from the first communication unit;
The address translation apparatus according to claim 1, further comprising: A LAN side communication unit for performing communication with the LAN side;
A WAN side communication unit that performs communication with the WAN side;
A SIP determination unit for determining whether the received packet is a SIP request packet transmitted from the WAN side, a SIP packet other than that, or a SIP packet;
A header field acquisition unit for acquiring a specified SIP message-header from a packet;
An address translation table having a URI and an IP address as a set;
An IP address conversion unit for rewriting the destination IP address of the IP header according to the URI of the To header field included in the payload of the SIP request packet received from the WAN side communication unit;
An address translation device comprising: An IP address acquisition unit for acquiring a source IP address from the received packet;
A method acquisition unit for extracting a method of the SIP packet;
When the method is register, the source IP address of the SIP packet as the IP address or the IP address of the Contact header field of the SIP packet;
A translation table registration unit for adding a pair with the URI of the To header field of the SIP packet to the address translation table;
An IP address conversion unit that transfers a packet to a conversion table registration unit when a SIP packet is received from the LAN side;
4. The address translation apparatus according to claim 3, further comprising:

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