TCP FIN scan FIN scan

Alias:
FIN scan
Field:
Security > network > TCP FIN scan

TCP/IP

Reading: The tea sea tweet the eye tweet
Full spelling: Transmission Control Protocol/Internet Protocol
Field:
Network technology > TCP/IP > TCP/IP

The protocol which is used standard with Internet and Intranet. The Department of Defense, being destroyed partly with mushroom, it was born with the process which develops the computer network which does not have the times when the whole stops.

Because it is mounted on UNIX usually, it spreads quickly, presently most has spread in the world. It is the protocol to which with the OSI reference model IP hits, 3rd layer (network layer), TCP 4th layer (transport layer) becomes the basis of HTTP and FTP etc.

TCP SYN scan

Alias:
SYN scan
Field:
Security > network > TCP SYN scan

Without leaving the log to the server, port scan is done, one of technique of “stealth scan”.

Actually trying connection, you call that you inspect whether or not the port of the server opens by port scan, but when connection is tried normally, because the log remains on server side, it becomes clear to do port scan. In order to evade this, procedure is made to discontinue by sending the packet which means of connected procedure the cancellation lastly, the fact that record is not made to leave to the log is SYN scan.

With TCP, the client sends the “SYN packet” to the server first, the server in the client the “ACK packet” replies, connection establishes by the fact that the client sends the ACK packet to the server lastly, but connection is discontinued in the SYN scan by transmitting the “RST packet” (reset) from the client lastly. In order to oppose to original gist, you do not have to do the fact that RST is used in this kind of use.

TCP SYN flood attack

Alias:
SYN flooding attack
Field:
Security > network > TCP SYN flood attack

It is the attack which tries the TCP connection which at one of technique of the DoS attack which drives the server to functional stop, is not established in large quantities.

Connection is established with TCP, the client transmits the “SYN packet” to the server, the server the “ACK packet” replies to the client, the procedure that is stepped on the client returns the ACK packet lastly. Until the last ACK packet reaches, server side “response it waits” and while it is state comes to the point of waiting, becomes not be able to open the resource of the memory territory and the like which is prepared for the connection. The attack person who has malice transmits mass SYN request, without sending the ACK packet purposely, leaves, when, server side among those “response it waits” and the number of connections exceeds the limit, becomes a state where connection cannot be accepted anew. This is SYN flood attack.

TCP wrapper

Reading: The tea sea tweet the wrapper
Field:
Security > network > TCP wrapper

Managing the offer of the service which is permanently stationed in the computer which is worked with the UNIX affiliation OS as a portion of the system, leads network monistically, communication past record (the log) the software which is retained. The program which operates on UNIX the protocol, TCP/IP (protocol) using, offers various services, but TCP wrapper holds down the TCP port which these programs use in communication with outside entirely, does the access control and the retention of communication past record. If TCP wrapper is used, it can appoint finely which it permits the access to some port from outside. It accepts the communication from the mosquito net and which IP address which offer which service and so on, it is possible to set every service. Be sure to be assumed that in the program which becomes the basis of security measure, to the server who is released to Internet should be introduced.

TD-CDMA

Reading: Tea D sea D m a
Full spelling: Time Division Code Division Multiple Access
Field:
Portable telephone > 3G > TD-CDMA

At one of 3rd generation carrying (3G), it is standardized CDMA2000 and W-CDMA (DS-CDMA) etc and also, on the one hand as the formula of IMT-2000.

With TD-CDMA, rising changing the descent to CDMA system finely with time division including time division duplex operation (TDD) technology, it communicates. With other system the channel of the descent can be unified with the rising which utilizes another frequency zone, frequency can be used effectively. In addition, it changes transmission speed softly by modifying the ratio of allotment time of the top and bottom, it is possible to offer the data transmission service of asymmetric speed efficiently.

Originally, but one side of the same W-CDMA standard as DS-CDMA and the like which NTT [dokomo] and the like has adopted formula, each company pointing to the thing of DS-CDMA system, because it calls “W-CDMA”, distinguishing with W-CDMA, it is designed in such a way that it is called. Because other than the being different of duplex system it is common with majority DS-CDMA, the technology for W-CDMA and the considerable part of the product are called available that way.

TDD Time division duplex operation

Reading: Tea D D
Full spelling: Time Division Duplex
Field:
Network technology > connection > TDD

The technique which simultaneous transmission and reception with such as radio communication (duplex communication) at one of the systems which are actualized, divides channel finely with the time base, changes transmission and reception to high speed.

If simultaneously bidirectionally it can do the base station of the portable telephone and the communication etc of the terminal, but it is not possible to communicate simultaneously bidirectionally at identical frequency. Simultaneous transmission and reception is actualized falsely with TDD due to the fact that many degrees change transmission and reception to brief.

Vis-a-vis this, dividing frequency zone into transmission and reception, as for the system which does simultaneous transmission and reception FDD (Frequency Division Duplex: The frequency division duplex operation) with you say. The third generation (3G) with standard IMT-2000 of the portable telephone, as for W-CDMA and CDMA2000 FDD, as for TD-CDMA and TD-SCDMA TDD is used.

TDM Time division multiplex

Reading: Tea D m
Full spelling: Time Division Multiplexing
Field:
Network technology > connection > TDM