Cisco provide both VPN-building ways by hardware and software. Which way to adopt for building your own VPN depends on several factors including: remote-access or site-to-site and the amount of users.
Cisco VPN Concentrator can provide from small business to large enterprise use for building VPN, it combines intranet,high quality of encryption.
All of Cisco routers can be used for building VPN as long as the features are met by software.
PIX Firewall: Private Internet eXchange is also a hardware machine for VPN building, it combines filtration, proxy server etc.
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Blockchain is also a open source software,it not only means its core is open, but the innovation can happen in acollaborative way.
Like Bitcoin, since it was created by Satoshi Nakamoto, it has been maintained by a core group, therefore, many innovation and services created around and on top of it have taken advantage ofit.
Being open-sourced is a powerful feature,the more open the blockchain is, the more ecosystem around it will become.
