Outbound connection
An outbound connection is a connection that one of your own devices starts towards something on the internet, such as a laptop opening a website. In Cyber Essentials, any device that can make outbound connections to the internet is in scope. The firewall control focuses on inbound traffic and sets no specific rule for outbound filtering.
- Term
- Outbound connection
- Also known as
- Outgoing connection, Outbound traffic
- Category
- Networks and firewalls
- Requirement area
- D. Scope; 1. Firewalls
- Questions
- None directly
- Reviewed against
- Requirements v3.3
What does the term outbound connection mean in Cyber Essentials?
An outbound connection is a connection that one of your own devices starts towards something on the internet, such as a laptop opening a website.
can establish outbound connections to devices via the internet
How does outbound connection apply to Cyber Essentials?
In plain terms
Every time someone in your office checks email, joins a video call or loads a web page, their device reaches out to the internet. That is an outbound connection: your side makes the call. It is the everyday traffic that lets people do their jobs.
What Cyber Essentials asks
Outbound connections matter most for deciding scope. The requirements apply to all devices and software in scope that meet any of three conditions, and one of them is the wording quoted above. In practice this means almost every laptop, desktop, phone and server is in scope, because nearly all of them reach the internet.
The firewall rules themselves are about inbound traffic. The requirements ask you to block unauthenticated inbound connections, approve and document inbound rules, and remove rules you no longer need. A boundary firewall is described as able to "restrict the inbound and outbound network traffic", but the scheme does not require you to filter outbound traffic. Doing so can still be sensible for servers, and some firewalls let you block known malicious sites.
Common mistakes
- Arguing a device is out of scope because nothing connects to it. If it can reach the internet, it is in scope.
- Confusing outbound rules with inbound ones when answering A4.6 and A4.8. Those questions are about what can come in.
See what is in scope and the firewall requirements. Related: inbound connection, scope.
Related terms
- Boundary firewallA boundary firewall is a network device that restricts inbound and outbound traffic between an organisation's network and the internet using firewall rules.
- Inbound connectionAn inbound connection is a connection that someone on the internet starts towards a device or service inside your network, rather than one your own devices start.
- ScopeScope is the networks, hardware and software assets, and cloud services that are included in a Cyber Essentials assessment.
- Port (network port)A port is a numbered doorway on a device that a particular kind of network traffic uses, for example secure web pages usually arrive on port 443.
- Port forwardingPort forwarding is a router setting that sends a particular kind of traffic arriving from the internet on to one chosen device inside your network, such as a CCTV recorder.
- Remote Desktop Protocol (RDP)Remote Desktop Protocol (RDP) is Microsoft's way of letting someone see and control a Windows computer or server from another device over a network.
Frequently asked questions
An outbound connection is a connection that one of your own devices starts towards something on the internet, such as a laptop opening a website. The definition follows the NCSC's Cyber Essentials: Requirements for IT Infrastructure v3.3.
Outbound connection relates to D. Scope; 1. Firewalls in the NCSC's Cyber Essentials: Requirements for IT Infrastructure v3.3. Read that section for the control your answers must show.
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