Possible Alternatives to Web Filtering Proxy
My Wi-Fi network is public and I am not able to install trusted Root CA certificates onto network devices. Can I still prevent access to adult sites?
If you are not able to install trusted Root CA certificates on the devices in your network (for example in public Wi-Fi) it is still possible to prevent access to some questionable categories of web sites by using DNS filtering. We have another project called DNS Safety that can help you with that. See the project at https://dnssafety.io.
DNS Safety Filter is a DNS forwarding server (like dnsmasq) with extensive filtering capabilities. It allows administrator to filter access to domain names by categories, easily block access to user specified domains and provides different access policies for different groups of machines in your network.
DNS Safety Filter is supposed to be deployed as primary DNS server in your local network and can forward DNS requests to your ISP’s DNS server, Google Public DNS, OpenDNS and other third party DNS providers.
Please note the DNS filter is able to prevent access to sites based on their domain name only. It is not possible to scan individual pages on the site and thus dynamic textual categorization is not possible.