To increase the security of the connection to your servers, or between the servers themselves, it is possible to use VPN (Virtual private network) technology. It provides an encrypted connection between clients. It is possible to connect individual workstations or entire offices this way.
We use OpenVPN technology, for this purpose. It is supported by the most devices and operating systems. It supports connecting using a shared key, certificate, or username and password. Communication takes place port 1194 using common TCP or UDP protocols by default. The encrypted tunnel can be created on the 2nd or 3rd network layer, according to usage.
In addition to OpenVPN, we also support IPsec. But only via Cisco ASA, as its implementation on Linux is unstable and our experience has shown frequent operational problems.