The advantages and disadvantages of PPTP, L2TP, OpenVPN, SSH

PPTP: connected, disconnected speed requirements firewall, router support, higher environmental requirements on the network.
L2TP: ability to penetrate, network anti-flash capability, suitable for PPTP can not use environment.
OpenVPN: the ability to penetrate the most suitable for the campus network, the company LAN restricted network environment, the first time you use to install virtual NIC.
SSH: local agent, suitable for browsing the web and watch videos, you need SSH connection with the use of the software and the browser.