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Glossary
description: >- “When I use a word,” Humpty Dumpty said in rather a scornful tone, “it means just what I choose it to mean – neither more nor less.”
| Term | Definition |
|---|---|
| Bridge | A network mode (or network device) which copies packets between two physical interfaces, without changing the content of the packets. Similar to a switch, a bridge copies packets from one physical network to another physical network, without modification. |
| Hub | A hub distributes packets from all connected devices to all other connected devices. A hub operates at the physical layer (layer 1) and has no insight into the contents of the data, and offers no protection against multiple devices transmitting at once. |
| Layer N | A reference to a layer in the OSI network model; typically used to describe the area of networking, such as layer 2 (raw packets), layer 4 (TCP and above), and so on. |
| MAC Address | A MAC address (Media Access Control), is the unique 6-byte addressed of a network card at the lowest layer. MAC addresses must be unique within a network. The first 3 bytes of the MAC address are known as the OUI (Organizational Unique Identifier); each manufacturer has a unique UI, which allows identifying (to some extent) what company has produced a network device. Since many network devices are re-branded or include network chipsets from other companies, this information is not always reliable. |
| NAT | Also known as Network Address Translation or Masquerading; a method where packets from multiple devices on a private network are rewritten to appear to be from a single device on the public network. |
| Packet | A packet represents a collection of data on the network transmitted as a single object.
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| Router | A network mode (or network device) which directs packets from one logical network to another (such as from a private network to an Internet connection, often utilizing NAT in the process). Routers are responsible for passing packets from one network to another, such as a private local network passing packets to a larger corporate network or the Internet. Routers modify packets to direct them to the new network. |
| Switch | A network device which connects multiple Ethernet devices, while keeping traffic separate. A switch operates purely at the data layer (layer 2), and typically has no insight into the types of packets or the protocols contained in the packet. |