emPSN in conjunction with JISC is able to offer schools and connected members the use of a Secure Network Resolver service sDNS.
What is the Service
The service is a filtered DNS resolver that provides interception where the FQDN or Target IP is known to be compromised or a risk. The inclusive service can be used by all connected members.
Clean service request – When the client makes a DNS request to a service that is clean (no reported security issues) the service will return the IP details like any standard DNS request.
Dirty service request – When the client makes a DNS request to a service that has been compromised the service will return the IP details for the safe warning page / IP. Where this is a URL/Web Request the returned IP will be for a safe block page resource.
Example block page – http://bad-domain.soc.ja.net/
When a member sees the block page, this is due to a FQDN or IP being intercepted by the service and referring the customer to a safe ip – the block page.
This will happen where the resource is known to be or is known to have been compromised. Once the FQDN/IP is effectively clean the service will return to normal operation.
False Positives or Block Page Queries
In the event of a user seeing the RPZ block screen, it contains links to support@empsn.org.uk
In order for the user to generate a false positive report. Clicking the link on the page populates a standard email message, alternatively we ask that you send the following information:
- Client IP:
- Queried Domain
- Queried Port:
- URL:
- Time of Access(UTC):
- Commend
Upon receipt of the request emPSN will assess the request to determine if this is a false positive or a user education matter. We expect the actual number of false positives to be less than 0.5% of all blocks.
For information on other DNS services from emPSN:
- DNS Services – https://www.empsn.org.uk/knowledgebase/dns-services/
- Reverse DNS/PTR Records – https://www.empsn.org.uk/knowledgebase/reverse-dns-ptr-records/
- DNS Hosting Services – https://www.empsn.org.uk/knowledgebase/dns-hosting-services/
- DNS – Secure Network Resolver – https://www.empsn.org.uk/knowledge-base/dns-secure-network-resolver/
- DNS – Secure Network Resolved – Setup – https://www.empsn.org.uk/knowledge-base/dns-secure-network-resolver-setup/
Should you require any further assistance on this and any other empsn services please contact us on support@empsn.org.uk
