The UK Government Connect Secure Extranet (GCSX) is a secure wide area network (WAN) that allows officials at local public-sector organizations to interact and share data privately and securely with central government departments, such as the National Health Service, the Criminal Justice Extranet and the Police National Network. The GCSX is a managed network service, collocated at multiple data centers, that exists separately from the networks of the central government’s departments.

The central departments connect to the GCSX through the Public Sector Interconnect, a secure WAN bridge that links central department network domains to enable secure communication outside the public Internet. In order to be allowed access to the Government Connect Secure Extranet, local government authorities must be in compliance with the Code of Connection (CoCo), and Good Practice Guide 13, which mandates specific IT controls for protective monitoring in order to prevent sensitive data from leaking out of the Government Connect Secure Extranet.