A wire crimper is a tool that you use to attach media connectors to the ends of cables. For instance, you use one type of wire crimper to attach RJ-45 connectors on Unshielded Twisted Pair (UTP) cable, and you use a different type of wire crimper to attach Bayonet Neill Concelman (BNCs) to coaxial cabling.
A wire map tester is a device that is similar in principle to the tone generator and locator, except that it tests all the wire connections in a UTP cable at once. This device also consists of two parts, which you connect to the opposite ends of a cable. The unit at one end transmits signals over all the wires, which are detected by the unit at the other end. A wire map tester can detect transposed wires, opens, and shorts, just as a tone generator and locator can, but it does all the tests simultaneously and provides you with a simple readout telling you what's wrong
Multifunction cable testers are handheld devices, that perform a variety of tests on a cable connection and compare the results to standard values that have been programmed into the unit. The result is that these are devices that anyone can use. You simply connect the unit to the cable, press a button, and the device comes up with a list of pass or fail ratings for the individual tests. Multifunction cable testers can test any of the following:
One of the most basic ways to identify and test a cable connection is to use a tone generator and locator cable tester. The tone generator is a device that you connect to a cable at one end, and which transmits a signal over the cable. The tone locator is a separate device that has a probe capable of detecting the generator's signal, either by touching it to the conductor in the cable, or simply by touching it to the insulation on the outside of the cable. When the locator detects the generator's signal, it emits an audible tone. You can use this type of device to test an entire cable, or to test the individual wire connections inside a UTP cable.
Tone generators are most commonly used to identify the cable belonging to a particular connection.
If you're performing an internal cable installation, and you forget to label one of your cables, you can connect the tone generator at the wall plate end and touch the probe to each of the cables at the patch panel end until you find the one that produces a tone. You can also use a tone generator and locator to test the individual wire connections inside a UTP cable.
Using this method, you can test for any major wiring faults that affect internal UTP cable installations.
Tone generator and locator Pros:
Tone generator and locator Cons:
A firewall is a system or group of systems that enforces an access control policy between two networks. How this is accomplished varies widely, but in principle, the firewall can be thought of as a pair of mechanisms to either block or permit traffic. Some firewalls place a greater emphasis on blocking traffic, while others emphasize permitting traffic. Probably the most important thing to recognize about a firewall is that it implements an access control policy.
Network layer firewalls
Network layer firewalls operate at a low level of the TCP/IP protocol stack as IP-packet filters, not allowing packets to pass through the firewall unless they match the rules. The firewall administrator may define the rules; or default built-in rules may apply. Modern firewalls can filter traffic based on many packet attributes like:
They can also filter based on protocols, TTL values, netblock of originator, domain name of the source, and many other attributes.
Application-layer firewalls work on the application level of the TCP/IP stack (i.e., all browser traffic, or all telnet or ftp traffic), and may intercept all packets traveling to or from an application. They block other packets without acknowledgement to the sender. Application firewalls can prevent all unwanted outside traffic from reaching protected machines.Firewalls can’t protect against attacks that don’t pass through it.
Types of firewalls
The term firewall is rather broad, because the features and effectiveness of any particular firewall vary greatly. However, firewalls in general can be classified into three basic forms, as outlined here:
A proxy server provides numerous advantages for connecting a local area network to the Internet. Acting as an Application-Layer Gateway, the proxy provides a strong defense from the outside world. Performing the duties of a firewall, however, is just one benefit of a proxy server. The proxy can also provide caching services to increase performance, logging services to track Internet use, tools to maximize the use of precious bandwidth, and content filtering to help keep unwanted data off the local network. The proxy can also utilize multiple connection types to easily provide redundancy and automatic failover in the event of a primary line failure.
The primary security features of Proxy Server are:
Search more about
Search in Google for