Address range (CIDR): what it is and how it is attacked
A group of numbered addresses on a network, written as a single line such as 192.0.2.0/24 rather than listed one by one.
Also known as
- CIDR
- subnet
- IP range
Typing any of them into the editor finds this object.
Why it matters on a security diagram
Lets a diagram say which addresses belong to which part of the network without drawing every device.
How it gets attacked, and what reduces it
How it gets attacked
- Ranges wider than intended, quietly granting access to neighbours
What reduces it
- Write firewall rules against named groups rather than wide ranges
- Re-check rules when a range grows, because the rule silently grows with it
Where it sits
- Group
- Network · The paths traffic travels along.
- Whose side, by default
- Ours · Belongs to the organisation the diagram is about.
- Catalogue identifier
- ip-range
Reviewed . CC BY 4.0.
Others in network
- The internetWAN · public networkEverything outside your organisation's control.
- Routergateway · layer 3Sends information from one network to another, the way a junction sends cars down different roads.
- Switchlayer 2 · LAN switchConnects the devices inside one building or floor, passing each message only to the machine it is addressed to.
- Remote access gatewayVPN · VPN concentrator · remote accessThe door staff use to reach the internal network from outside.
- Internet network operatorASN · autonomous system · AS number · BGP network · peeringOne organisation's own network on the internet, identified by a number so every other network knows whose it is.
The network group lists all 6 of them side by side.
Address range on your own diagram
Open the editor, press N, and type CIDR. The object is placed and connected to whatever was selected, and Tab adds the next one already joined to it. Nothing is uploaded: the page is served with a Content Security Policy that forbids the browser from making any outbound request at all.
Open the diagram maker