# Network devices

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## Network

A computer network is a digital telecommunications network which allows nodes to share resources. Eg: 2 PCs connected through a cable.

## Nodes

* Router
* Switch
* Firewall (hardware)
* Server - device that provides functions or services for clients
* Client - device that accesses a service made available by a server. (together with server - end hosts/points)

### Switches

* used to forward traffic within a LAN (provide connectivity to hosts within same LAN)
* have many network interfaces/ports for endhosts to connect to (usually 24+)
* do not provide connectivity between LANs or over the internet
* Cisco - Catalyst

### Routers

* are used to provide connectivity between LANs
* used to send data over the internet
* have fewer network interfaces than switches
* Cisco - ISR

### Firewalls

* monitor and control network traffic based on configured rules
* can be placed 'inside the network' or 'outside the network'
* 'Next generation firewalls' when they include modern and advanced filtering capabilities (IPS - Intrusion Prevention System)
* Cisco - ASA, Firepower
* Network firewalls - hardware devices that filter traffic between networks
* Host-based firewalls - software applications that filter traffic entering and exiting a host machine, like PC

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