Router device, packet control method based on prefix management, and program

1. A router device for redistributing, to a node, a prefix distributed from a prefix distributing device to route a packet based on an IPv6 address, the router device comprising:

hardware including a processor;

a prefix management unit implemented at least by the hardware and which creates a filtering rule including an indication of passage or block of a packet from the node based on the prefix distributed from the prefix distributing device and a prefix in a source IP address received from the node;

a filter unit implemented at least by the hardware and which passes or blocks the packet from the node according to the filtering rule created by the prefix management unit;

a prefix storage unit which stores the prefix, from the prefix distributing device, together with discriminative data used to determine whether the prefix, in the source IP address, is usable; and

a Router Advertisement (RA) sending unit implemented at least by the hardware which:

periodically checks on contents, comprising a deletion flag indicating whether to delete the prefix, stored in the prefix storage unit;

creates option information on an RA packet capable of identifying whether the prefix, in the source IP address, is usable or unusable based on the prefix, from the prefix distributing device;

adds data to the RA packet and indicative of deletion of the prefix, and the discriminative data stored in the prefix storage unit; and

sends to another node an RA packet including the created option information;

wherein when a received packet meets the indication of blocking the packet in the filtering rule, the filter unit discards the packet and notifies the prefix management unit of the source IP address of the discarded packet,

wherein, based on the data, the prefix management unit determines that the prefix included in the notified source IP address is a prefix unusable and to be deleted,

wherein the indication of blocking the packet in the filtering rule is that the received packet includes, in the source IP address, the prefix which is not distributed to the node by the router device, and

wherein when the packet including the prefix in the source IP address is received from the node, the filter unit discards the packet.

2. The router device according to claim 1 , wherein when the filter unit discards the packet, the RA sending unit immediately sends to the another node an RA packet including option information capable of identifying that the prefix included in the source IP address of the packet is unusable.

3. The router device according to claim 1 , wherein when a prefix is distributed from the prefix distributing device, the prefix management unit sets discriminative data corresponding to the prefix to a value indicating that the prefix is usable, and when a new prefix is distributed from the prefix distributing device, the prefix management unit changes the discriminative data corresponding to the already distributed prefix to a value indicating that the prefix is unusable.

4. A packet control method based on prefix management performed by a router device for redistributing, to a node, a prefix distributed from a prefix distributing device to route a packet based on an IPv6 address, the packet control method based on prefix management comprising:

creating a filtering rule including an indication of passage or block of a packet from the node based on the prefix distributed from the prefix distributing device and a prefix in a source IP address received from the node;

passing or blocking the packet from the node according to the created filtering rule;

storing the prefix, from the prefix distributing device, together with discriminative data used to determine whether the prefix, in the source IP address, is usable; and

periodically checking on the stored prefix and the discriminative data comprising a deletion flag indicating whether to delete the prefix;

creating option information on an RA packet capable of identifying whether the prefix, in the source IP address, is usable or unusable based on the stored prefix;

adding data to the RA packet and indicative of deletion of the prefix, and the discriminative data; and

sending to another node an RA packet including the created option information;

wherein when a received packet meets the indication of blocking the packet in the filtering rule, the packet is discarded and, based on the data, the prefix included in the source IP address of the discarded packet is determined to be a prefix unusable and to be deleted,

wherein the indication of blocking the packet in the filtering rule is that the received packet includes, in the source IP address, the prefix which is not distributed to the node by the router device, and

wherein when the packet including the prefix in the source IP address is received from the node, the packet is discarded.

5. A non-transitory computer readable information recording medium storing a packet control program based on prefix management, which is installed in a router device for redistributing, to a node, a prefix distributed from a prefix distributing device to route a packet based on an IPv6 address, the packet control program based on prefix management, when executed by a processor, performs a method for:

creating a filtering rule including an indication of passage or block of a packet from the node based on the prefix distributed from the prefix distributing device and a prefix in a source IP address received from the node; and

passing or blocking the packet from the node according to the created filtering rule;

storing the prefix, from the prefix distributing device, together with discriminative data used to determine whether the prefix, in the source IP address, is usable; and

periodically checking on the stored prefix and the discriminative data comprising a deletion flag indicating whether to delete the prefix;

creating option information on an RA packet capable of identifying whether the prefix, in the source IP address, is usable or unusable based on the stored prefix;

adding data to the RA packet and indicative of deletion of the prefix, and the discriminative data; and

sending to another node an RA packet including the created option information;

wherein when a received packet meets the indication of blocking the packet in the filtering rule, the packet is discarded and, based on the data, the prefix included in the source IP address of the discarded packet is determined to be a prefix unusable and to be deleted,

wherein the indication of blocking the packet in the filtering rule is that the received packet includes, in the source IP address, the prefix which is not distributed to the node by the router device in the source IP address, and

wherein when the packet including the prefix in the source IP address is received from the node, the packet is discarded.

6. The router device according to claim 1 , wherein

the prefix distributing device is accessible to the Internet, the router device is communicable with the prefix distributing device through a Wide Area Network, and

the router is communicable with the node through a LAN to relay communication between the node and the prefix distributing device.

7. The router device according to claim 1 , wherein when the prefix is changed, a prefix storage unit stores the prefix before change and the prefix after change as a set.

8. The router device according to claim 1 , wherein the RA sending unit sends the RA packet with the data indicative of deletion of one prefix and data indicative of distribution of another prefix added thereto.

9. The router device according to claim 1 , wherein the RA sending unit sets “0” in a “Valid Lifetime” and “0” in a “Preferred Lifetime” of the RA packet.