> ## Documentation Index > Fetch the complete documentation index at: https://devzone.nayax.com/llms.txt > Use this file to discover all available pages before exploring further. # Cortina Network Requirements > Connection methods, VPN setup, and IP addresses to whitelist so Cortina terminals can reach Nayax. For communication between Nayax and the Integrator, we support the following methods: * HTTPS TLS 1.2/1.3 * VPN S2S (Site-to-Site VPN) If the integrator wishes to establish a VPN tunnel to the Nayax server, the VPN tunnels for Test and Production will be established during the initial setup stage. The integrator will be asked to complete a VPN request form and join a technical call. During the call, the tunnels will be created and tested. Integration testing will be performed only after the VPN is set up and working. **Authentication with a VPN** In cases where a VPN is established, the integrator may skip the `Start Session` authentication stage. However, Nayax recommends implementing it in all integrations. ## Whitelist IPs To ensure smooth communication, the Integrator must whitelist the following Nayax public IP addresses. | Environment | Region | IP Addresses | | :---------- | :----------------- | :-------------------------------------------------------------------- | | Production | Germany (DE) | `137.221.37.126`, `185.159.234.2` | | Production | United States (US) | `72.28.118.100`, `72.28.111.132`, `185.159.233.2` | | Production | Israel (IL) | `185.159.232.2`, `84.110.125.194`, `82.102.172.206`, `212.179.76.198` | | QA | — | `31.154.55.2` | If required, the Integrator should also allow access from the Nayax QA environment so the Nayax QA team can conduct automation testing. ## See also * [Cortina Integration](/docs/cortina/cortina-integration) * [Start Session](/docs/cortina/start-session/cortina-auth)