NETGEAR DG834G, Справочное руководство

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Reference Manual for the Model Wireless ADSL Firewall Router DG834G
Network and Routing Basics B-11
202-10006-05, June 2005
Denial of Service Attack
A hacker may be able to prevent your network from operating or communicating by launching a
Denial of Service (DoS) attack. The method used for such an attack can be as simple as merely
flooding your site with more requests than it can handle. A more sophisticated attack may attempt
to exploit some weakness in the operating system used by your router or gateway. Some operating
systems can be disrupted by simply sending a packet with incorrect length information.
Ethernet Cabling
Although Ethernet networks originally used thick or thin coaxial cable, most installations currently
use unshielded twisted pair (UTP) cabling. The UTP cable contains eight conductors, arranged in
four twisted pairs, and terminated with an RJ45 type connector. A normal straight-through UTP
Ethernet cable follows the EIA568B standard wiring as described below in
Table B-1
.
Category 5 Cable Quality
Category 5 distributed cable that meets ANSI/EIA/TIA-568-A building wiring standards can be a
maximum of 328 feet (ft.) or 100 meters (m) in length, divided as follows:
20 ft. (6 m) between the hub and the patch panel (if used)
295 ft. (90 m) from the wiring closet to the wall outlet
Table B-1. UTP Ethernet cable wiring, straight-through
Pin Wire color Signal
1 Orange/White Transmit (Tx) +
2 Orange Transmit (Tx) -
3 Green/White Receive (Rx) +
4 Blue
5 Blue/White
6 Green Receive (Rx) -
7 Brown/White
8 Brown