Nippon Telegraph and Telephone Corporation

Kazuaki Chikira

Takehiro Moriya

Takeshi Mori

Hideo Mori

Akio Jin

Naoki Iwakami

An abnormal traffic detection apparatus for detecting an abnormal traffic toward a communication apparatus by using information on traffics passing through a switch, comprising destination IP address counting units (Cto C) configured to store amount information on amount of traffics as an amount information table corresponding to each communication apparatus, a traffic separating unit () for registering amount information on a new destination IP address in the amount information table corresponding to the destination IP address, each time a traffics having the new destination IP address passes through the switch, and storing the amount information in the amount information table corresponding to each communication apparatus, and abnormal traffic judging units (Jto J) for detecting an abnormality of the traffic amount flowing through the switch on the basis of the amount information stored in the amount information table.

Abnormal traffic detection apparatus, abnormal traffic detection method and abnormal traffic detection program

A traffic monitoring system () monitors traffics flowing through a network (); when an abnormal traffic is detected, identifies an attack source network, a source of an attack, on the basis of attack source information indicating a source device from which the abnormal traffic is transmitted, which is obtained by an analysis of the abnormal traffic, and also identifies an attack destination network, a destination of the attack, on the basis of attack destination information indicating a destination device to which the abnormal traffic is to be transmitted, which is obtained by the analysis of the abnormal traffic; notifies an administrator of the attack source network of the attack source information by acquiring administrator information corresponding to the identified attack source network; and notifies an administrator of the attack destination network of the attack destination information by acquiring administrator information corresponding to the identified attack destination network.

Network monitoring apparatus, network monitoring method, and network monitoring program

An input signal is time-frequency transformed, then the frequency-domain coefficients are divided into coefficient segments of about 100 Hz width to generate a sequence of coefficient segments, and the sequence of coefficient segments is split into subbands each consisting of plural coefficient segments. A threshold value is determined based on the intensity of each coefficient segment in each subband. The intensity of each coefficient segment is compared with the threshold value, and the coefficient segments are classified into low- and high-intensity groups. The coefficient segments are quantized for each group, or they are flattened respectively and then quantized through recombination.

Audio signal coding and decoding methods and apparatus and recording media with programs therefor

An object of the invention is to provide a method for compressing digital input signals at high compression efficiency and reproducing the input data perfectly. The method includes the steps of: converting a digital input signal in each frame to bitstreams according to a sign-magnitude format; deblocking the bitstreams into individual bits; joining each bit in a time sequence while retaining an identical chronological order of bits in all the frames; and reversibly encoding each bitstream obtained by joining the bits. And, the reversible decoding method includes the steps of: reversibly decoding a reversible code sequence in each frame; deblocking the bitstreams obtained by reversible decoding into individual bits; joining each bit in a time sequence while retaining an identical chronological order of bits in all the frames; and joining successive frames obtained by joining the bits.

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Tokyo, Japan

Kazuaki Chikira