London Grid for Learning

schools conference 28th april 2014

LGfL Schools Conference 2014Supporting the New Curriculum

Techspeak made SimpleBrian DurrantChief Executive LGfL

Purpose: to de-mystify some network related tech speak Audience: teachers – non-tech

• Digital• Network address• Internet Protocol• DHCP• DNS• Gateway• Subnet• Ports• DMZ• Domain• Firewall

A simple network

4 – way handshake

1. Are you there station 42? 2. Yes – I’m ready3. Here it is4. Ok – got it!

A Protocol – an agreed method of communication

Maths Lesson

0000 00010000 00100000 00110000 0100

128 64 32 16 8 4 2 1 1 0 0 0 0 0 0 0 = 1 0 0 0 0 0 0 1 = 1 1 1 1 1 1 1 1 = 0 0 0 0 0 0 0 0 = 0 1 0 0 0 0 0 1 = A

Internet IPv4

11111111.11111111.11111111.11111111 = 256 x 256 x 256 x 256 = 4,294,967,296

‘Station’ address (IP Address) : 82.2.159.118 (4 ‘octets’)

Network No 82.2.159 Station No 118 (for example)

Router – is this for this network? (‘subnet’) – or another ?

Internet IPv4

11111111.11111111.11111111.11111111 = 256 x 256 x 256 x 256 = 4,294,967,296

‘Station’ address (IP Address) : 82.2.159.118 (4 ‘octets’)

Network No 82.2.159 Station No 118 (for example)

Router – this network (‘subnet’) – or another ?

4.3bn - enough? Private addresses - 10.X.X.X 192.168.X.X (internal only)Public (‘real world’) addresses - 82.2.159.118

DHCP - Dynamic Host Configuration Protocol

Most computers don’t have an IP address they ‘own’An IP address is allocated ‘on loan’ – a dynamic addressSome devices need a fixed IP address (e.g. a printer)Some need a ‘public’ address (e.g. a web server)Start > cmd > ipconfig

Subnet mask (e.g. 255.255.255.0)

To guide the traffic…11111111.11111111.11111111.00000000[ ------ Network address ------ ] [host address][ ------- Subnet identity ---------] [device identity] = 254 devices“look at the first 24 bits to decide: – here, or elsewhere?”

11111111.11111111.11111000.00000000[ ------- Subnet identity ----][device identity] = 2046 devicesSubnet mask :

255.255.248.000

e.g. 10.163.2.0/21

Gateway ( e.g. 192.168.0.1 )

The link to the outside world – usually the router (i.e the link to the next network)

So – all computers/devices on a network have an address - some static, some dynamic - some private (local), some public (world-wide)

82.2.159.118

DNS Domain Name System

Where’s my DNS service ? (e.g. 194.168.4.100 - via DHCP service)

Hey DNS – where’s “LGFL.net” ?

DNS : “It’s at 82.2.159.118”

OK Router – “Connect me to 82.2.159.118”

OK Router – “Connect me to 82.2.159.118”

A secure filtered connection to the Internet…..

using Webscreen 2.0

What are ‘Port Numbers’ ?

82.2.159.118 : 80

DMZ – ‘Demilitarised Zone’

A subnet which exposes external-facing services to an untrusted network, usually the Internet.

Provides a layer of security to the main internal network.

A Domain Name

The part of a network address which identifies it as belonging to a particular domain.

Used for websites - www.conference.lgfl.net

And email addresses – brian@lgfl.net

Firewall

• TCP/IP – is fast, powerful and therefore dangerous • Connected to the Internet, your school’s network is connected

to every other computer connected to the Internet !• A firewall helps prevent hackers or malicious software from

gaining access to your network/computer. • Every LGfL connection comes with a dedicated managed firewall

A Tension - A Balance

Absolute _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ AbsoluteSecurity Freedom

Questions

London Grid for Learning

schools conference 28th april 2014