Solution:

OpenVPN (Open Virtual Private Network) is a means of interconnection of several computers through an untrusted public network. It is easily possible to reach a situation where connected computers are able to communicate with each other as if they were connected in a single closed private network (this network is consequently trusted). Using client-server architecture, OpenVPN is capable of ensuring a direct connection between computers behind NAT without any need to configure NAT. It has a few ways to authenticate clients – using a pre-shared key, a certificate or a username and password. OpenVPN uses the officially assigned port 1194, which is applied as a default in newer versions. It offers two types of network interfaces (Universal TUN and TAP driver), which enable creation of an IP tunnel (TUN) on the third layer of the ISO/OSI or on the second layer (layer-2 Ethernet TAP), which is able to transmit any type of data. OpenVPN uses a common network protocols (TCP and UDP) and thus creates an alternative to IPsec protocol. Restrictions in Conel and Spectre routers Routers allow to create only two OpenVPN tunnels simultaneously Routers only support TUN adapter Routers can not be used as a multiclient server