# Introduction to Networks Cisco
## Network components
### Host roles
hosts = end devices = clients
hosts hebben een nummer die hun identificeerd, dit zijn IP adressen.

servers zijn computers met software die informatie geeft, zoals email, web pagina's aan andere end devices in het netwerk.

### Peer-to-peer
Meestal runnen clients en servers op verschillende computers, maar het kan ook mogelijk zijn dat 1 computer wordt gebruikt voor beide rollen. Dit heeft een peer-to-peer network.
**De voordelen:**
* makkelijk op te zetten
* minder complex
* goedkoper want er is geen network device of server nodig
* kan gebruikt worden voor simpele taken, zoals printen

**De nadelen:**
* geen gecentraliseerde administration
* niet zo veilig
* niet schaalbaar
* lagere performance

### End devices
Elk end device op een netwerk heeft een adres. Deze adressen zijn nodig om te weten naar waar hun communicatie moet.
Een end device is een source of een destiantion.

### Intermediary devices
Intermediary devices connecteren de end devices aan het netwerk. Ze gebruiken de destination end device adressen om het path te bepalen van een message.

### Network media
Communication gaat over een media.
Er zijn 3 soorten media
* **metal wires within cables** - data is encoded in elektrische pulsen.
* **glass of plastic fibers (fiber-optic cable)** - data is encode in licht pulsen.
* **wireless transmission** - data is encoded via electromagnetic waves.

Kriteria voor het kiezen van een media:
* max afstand
* de omgeving
* de hoeveelheid data
* de kostprijs

## Network representation
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Hoe is elke device en media geconnecteerd:
* **Network interface card (nic)** - fysieke connectie tussen end device en het netwerk.
* **fysieke poort** - conector op netwerk device die de media verbind met een end device of een netwerk device
* **interface** - speciale poort op netwerk device die connecteerd naar individueel netwerk.

### Topology diagrams
deze documenteren het netwerk. Er zijn 2 soorten physical en logical.

**Physical Topology Diagrams**
Deze illustreren de fysieke locatie van intermediary devices en hun kabels.

**Logical Topology Diagrams**
Deze illustreren devices, poorten, en addressing schema's en welk media gebruikt wordt.

### WAN and LAN
Je weet wel wat het verschil is tussen beide

## Internet connections
### Soho
DSL: digital subscriber liners, grote bandbreete, hoge availability en always-on connection. gaat over telefoon lijn.

### Business connection
DLL: dedicated leased line, circuits in service providers, connecteerd offices die niet bij elkaar liggen.
Metro ethernet: ethernet WAN. ethernet extend LAN access.

### Converging network
Traditional seperate networks

Converget netwoks

## Reliables network
### Fault tolerance
Device failure, quick recovery after failure
als 1 pad faald dan wordt de message direct doorverwezen via een andere weg.
Packet switching splits traffic into packets that are routed over a shared network.

### Scalabilty
Snel seport voor nieuwe users en app. zonder dat de performance naar benenden gaat

### Quality of service (QoS)
Network bandwidth is measured in the number of bits that can be transmitted in a single second, or bits per second (bps).
When the volume of traffic is greater than what can be transported across the network, devices will hold the packets in memory until resources become available to transmit them.

### Network security
* Confidentiality - Data confidentiality means that only the intended and authorized recipients can access and read data.
* Integrity - Data integrity assures users that the information has not been altered in transmission, from origin to destination.
* Availability - Data availability assures users of timely and reliable access to data services for authorized users.

## Network trends
### Bring your own device
Persoonlijk device in proffesioneel netwerk.

### Online collaboration
### Video communications
### Cloud computing
Cloud computing is one of the ways that we access and store data. Cloud computing is possible because of data centers.

## Network security
* Viruses, worms, and Trojan horses - These contain malicious software or code running on a user device.
* Spyware and adware - These are types of software which are installed on a user’s device. The software then secretly collects information about the user.
* Zero-day attacks - Also called zero-hour attacks, these occur on the first day that a vulnerability becomes known.
* Threat actor attacks - A malicious person attacks user devices or network resources.
* Denial of service attacks - These attacks slow or crash applications and processes on a network device.
* Data interception and theft - This attack captures private information from an organization’s network.
* Identity theft - This attack steals the login credentials of a user in order to access private data.

**Solutions**
* Antivirus and antispyware - These applications help to protect end devices from becoming infected with malicious software.
* Firewall filtering - Firewall filtering blocks unauthorized access into and out of the network. This may include a host-based firewall system that prevents unauthorized access to the end device, or a basic filtering service on the home router to prevent unauthorized access from the outside world into the network.

Larger networks and corporate networks use antivirus, antispyware, and firewall filtering, but they also have other security requirements:

* Dedicated firewall systems - These provide more advanced firewall capabilities that can filter large amounts of traffic with more granularity.
* Access control lists (ACL) - These further filter access and traffic forwarding based on IP addresses and applications.
* Intrusion prevention systems (IPS) - These identify fast-spreading threats, such as zero-day or zero-hour attacks.
* Virtual private networks (VPN) - These provide secure access into an organization for remote workers.

# Basic switch and end device configuration
## Cicso ios access

## Ios navigation
As a security feature, the Cisco IOS software separates management access into the following two command modes:

* User EXEC Mode - This mode has limited capabilities but is useful for basic operations. It allows only a limited number of basic monitoring commands but does not allow the execution of any commands that might change the configuration of the device. The user EXEC mode is identified by the CLI prompt that ends with the > symbol.
* Privileged EXEC Mode - To execute configuration commands, a network administrator must access privileged EXEC mode. Higher configuration modes, like global configuration mode, can only be reached from privileged EXEC mode. The privileged EXEC mode can be identified by the prompt ending with the # symbol.



## Command structure


### Confure password
( het wachtwoord in dit voorbeeld is cisco)

Als je erna terug alle rechten wil

Je kan ook paswoord encryptie gebruiken

### Configuration file
* startup-config - This is the saved configuration file that is stored in NVRAM. It contains all the commands that will be used by the device upon startup or reboot. Flash does not lose its contents when the device is powered off.
* running-config - This is stored in Random Access Memory (RAM). It reflects the current configuration. Modifying a running configuration affects the operation of a Cisco device immediately. RAM is volatile memory. It loses all of its content when the device is powered off or restarted.

### Ip addresses
Cisco IOS Layer 2 switches have physical ports for devices to connect. These ports do not support Layer 3 IP addresses.

### Clan op cisco

## Protocols
### Networks
* **Unicast** - Information is being transmitted to a single end device.
* **Multicast** - Information is being transmitted to a one or more end devices.
* **Broadcast** - Information is being transmitted to all end devices.

### Protocols interactions