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1.7. Used terms, glossary and shortcuts

1.7.1. Network related

Base 10

Well known decimal number system, represent any value with digit 0-9.

Base 16

Usually used in lower and higher programming languages, known also as hexadecimal number system, represent any value with digit 0-9 and char A-F (case insensitive).

Base 85

Representation of a value with 85 different digits/chars, this can lead to shorter strings but never seen in the wild.

Bit

Smallest storage unit, on/true (1) or off/false (0)

Byte

Mostly a collection of 8 (but not really a must - see older computer systems) bits

Device

Here, hardware of network connection, see also NIC

Dual homed host

A dual homed host is a node with two network (physical or virtual) interfaces on two different links, but does not forward any packets between the interfaces.

Host

Generally a single homed host on a link. Normally it has only one active network interface, e.g. Ethernet or (not and) PPP.

Interface

Mostly same as “device”, see also NIC

IP Header

Header of an IP packet (each network packet has a header, kind of is depending on network layer)

Link

A link is a layer 2 network packet transport medium, examples are Ethernet, Token Ring, PPP, SLIP, ATM, ISDN, Frame Relay,...

Node

A node is a host or a router.

Octet

A collection of 8 real bits, today also similar to “byte”.

Port

Information for the TCP/UDP dispatcher (layer 4) to transport information to upper layers

Protocol

Each network layer contains mostly a protocol field to make life easier on dispatching transported information to upper layer, seen in layer 2 (MAC) and 3 (IP)

Router

A router is a node with two or more network (physical or virtual) interfaces, capable of forwarding packets between the interfaces.

Socket

An IP socket is defined by source and destination IP addresses and Ports and (binding)

Stack

Network related a collection of layers

Subnetmask

IP networks uses bit masks to separate local networks from remote ones

Tunnel

A tunnel is typically a point-to-point connection over which packets are exchanged which carry the data of another protocol, e.g. an IPv6-in-IPv4 tunnel.

1.7.1.1. Shortcuts

ACL

Access Control List

API

Application Programming Interface

ASIC

Application Specified Integrated Circuit

BSD

Berkeley Software Distribution

CAN-Bus

Controller Area Network Bus (physical bus system)

ISP

Internet Service Provider

KAME

Project - a joint effort of six companies in Japan to provide a free IPv6 and IPsec (for both IPv4 and IPv6) stack for BSD variants to the world www.kame.net

LIR

Local Internet Registry

NIC

Network Interface Card

RFC

Request For Comments - set of technical and organizational notes about the Internet

USAGI

UniverSAl playGround for Ipv6 Project - works to deliver the production quality IPv6 protocol stack for the Linux system.

1.7.2. Document related

1.7.2.1. Long code line wrapping signal char

The special character “¬” is used for signaling that this code line is wrapped for better viewing in PDF and PS files.

1.7.2.2. Placeholders

In generic examples you will sometimes find the following:

<myipaddress>

For real use on your system command line or in scripts this has to be replaced with relevant content (removing the < and > of course), the result would be e.g.

1.2.3.4

1.7.2.3. Commands in the shell

Commands executable as non-root user begin with $, e.g.

$ whoami

Commands executable as root user begin with #, e.g.

# whoami