The Department for Education (DfE) continually refines its web filtering guidelines to address new and emerging digital risks. In October 2024, the Filtering and Monitoring Standards for Schools and Colleges mentioned real-time filtering for the first time - highlighting the growing requirement for this advanced form of filtering.
This article explains what real-time, content-aware filtering is, how it works, and 4 DfE guidelines that it can help schools to meet and even exceed.
What is real-time, content-aware web filtering and how does it work?
There are many types of web filter available on the market, but real-time, content-aware filtering sits at the top of the pack. To understand why, it’s important to know how web filtering works.
Web filters manage access to internet content in order to protect students from harmful or inappropriate material. The most common web filters used in education are: DNS, URL, content-aware, and real-time, content-aware.
DNS and URL filters deny or approve access to content based on static lists of blocked websites or web pages. If a user attempts to visit a domain or URL that is on the blocklist, they will be denied entry.
Content-aware filters look beyond the address bar. They analyse the content, construction and context of web pages to detect potential risks. While this achieves higher accuracy than DNS and URL filters, assessments are often based on versions of pages that are days, weeks or even months old. In this rapidly changing environment, this approach can leave students and networks exposed.
Real-time, content-aware filters offer the most advanced form of filtering. The content, construction and context of every page is assessed in real-time, at the point of request. This means that no matter how recently content was created or updated, risks can be immediately identified and blocked.
What are the DfE filtering guidelines?
The main document from the Department for Education (DfE) pertaining to filtering is the Filtering and Monitoring Standards for Schools and Colleges, which outline the 4 standards your setting should already be meeting. Filtering and monitoring guidelines can also be found in the Keeping children safe in education (KCSIE) guidance.
Though not an official government publication, the UK Safer Internet Centre’s (UK SIC) Appropriate Filtering for Education Settings is another valuable filtering resource for schools and colleges. Indeed, it is referenced by both KCSIE and the Filtering and Monitoring Standards.
Informed by consultations with IT professionals and school leaders, the UK SIC’s recommendations can influence updates to official DfE guidelines. As a result, it provides educators with a useful indication of future filtering requirements.
How real-time web filtering meets & exceeds DfE guidelines
1. Overcome technical limitations
“You need to understand (...) technical limitations, for example, whether your solution can filter real time content.”
- Standard 2, Filtering and Monitoring Standards (DfE)
“Schools should consider (...) the extent to which (http and https) content is analysed as it is streamed in real time to the user and blocked.”
- Appropriate Filtering for Education Settings (UK SIC)
The DfE states that settings must review their filtering provision at least once every academic year. The review should address potential technical limitations, which includes whether it filters content in real time. In other words, if it does not, this is considered a disadvantage.
A reason for this is that non-real-time filters experience a delay between a user trying to visit a page and its content being accurately assessed, as the filter must request information on the version of the page it has available. During this time, access may be granted to content that is potentially inappropriate. In a world where harmful online content is proliferating at a rapid pace, the potential risk this delay presents increases.
The personalised nature of certain web pages also means that non-real-time filters may be unable to obtain an accurate depiction of content individual students will be shown. For example, a social media site will present a login page, or a feed of tailored content, depending on the visitor. The filter is therefore left with inadequate evidence on which to base a decision to confirm or deny access.
A real-time content filter removes the delay and analyses the specific version of the page a user is requesting to see, overcoming these technical limitations.
2. Defend against AI-enabled risks
“You need to understand (...) how your school or college uses technology, including (...) generative AI tools.”
- Standard 2, Filtering and Monitoring Standards (DfE)
In October 2024 the DfE updated its standards to include in the filter review process a consideration of how your setting uses AI tools. The implication being that if AI technology is present (keep in mind that many teachers and students use some form of AI), you need a filter that can mitigate the associated risks.
Generative AI tools, for example, can produce vast amounts of potentially inappropriate content (text, images and videos) in seconds. What a user requests from these tools does not necessarily appear in the URL, meaning URL and DNS-based filters are unable to identify the category of content being consumed.
Content-aware filters are met with a similar issue, as they base decisions to permit or restrict access on earlier variants of the page. Real-time, content-aware filters inspect the content that is being requested at that specific moment, so they can accurately assess the nature of material being presented and respond accordingly.
3. Block VPNs and proxy services
“Check with your provider to find out whether your filtering system (...) blocks technologies and techniques that allow users to get around the filtering, such as VPNs, proxy services and end-to-end encryption methods.”
- Standard 3, Filtering and Monitoring Standards (DfE)
“Consider (...) the extent and ability to identify and manage technologies and techniques used to circumvent the system, for example VPN, proxy services, DNS over HTTPS and ECH.”
- Appropriate Filtering for Education Settings (UK SIC)
For as long as there have been web filters in schools, there have been students attempting to circumvent them. As technology advances, their means of doing so become increasingly sophisticated. IT staff are regularly having to defend against circumvention methods, including end-to-end encryption, VPNs and proxy services. The DfE expects schools to effectively block such techniques, or at the very least identify their use as early as possible.
Real-time filtering provides the most robust defence against such circumventions. Proxy anonymisers, for example, enable students to disguise their internet activity behind harmless-looking URLs. Proxy services regularly move between different web pages to avoid detection, and updated lists of proxies are shared on platforms such as Discord.
Content filters can recognise and block pages utilising proxy software as it is revealed in the construction of pages. However, as proxies frequently move between domains, only real-time filtering can offer assurance that proxies will be blocked as soon as they go live. By analysing older versions of pages, non-real-time filters are more likely to let these risks through, meaning the issue can go unnoticed for hours, days or even weeks.
4. Protect students without hindering teaching and learning
“Filtering systems should block harmful and inappropriate content, without unreasonably impacting teaching and learning.”
- Standard 3, Filtering and Monitoring Standards (DfE)
“Be careful that ‘over blocking’ does not lead to unreasonable restrictions as to what children can be taught with regard to online teaching and safeguarding.”
- Keeping Children Safe in Education 2024 (DfE)
Web filters are designed to block harmful content, but their ultimate purpose is to allow students to access as much of the web as possible. Filters that block content unnecessarily (often to make up for an inability to decipher the type of content being accessed) hinder students’ learning and disrupt lessons.
In contrast, the targeted approach of real-time web filters facilitates a rich online learning experience for students. The filter blocks pages rather than sites, and only does so if risks are apparent in the specific content the user is attempting to view. Schools can benefit from educational pages on sites like Reddit and YouTube, for example, while protecting students from the inappropriate and harmful content that also exists on these platforms.
The DfE dedicates an entire standard to the need to ensure filtering is not “unreasonably impacting teaching and learning”. Real-time, content-aware filters are unmatched in their ability to deliver this kind of service.
Compliance with government legislation and guidelines is a necessity for schools, colleges and MATs. However, with so many solutions to choose from, we understand it can be difficult to know which is the right choice for your environment. Deploying the right technology can provide peace of mind that students are protected and your setting is fulfilling its digital safeguarding responsibilities.
If you have any questions about web filtering or related DfE guidelines, contact our digital safety experts at enquiries@smoothwall.com. We’re ready to help.
