To enable VPN tunnels between individual host computers or entire networks that have a firewall between them, you must open the following ports: PPTP. To allow PPTP tunnel maintenance traffic, open TCP 1723. To allow PPTP tunneled data to pass through router, open Protocol ID 47. L2TP over IPSec. To allow Internet Key Exchange (IKE), open UDP 500.

The VPN tunnel will allow remote computers to think that they are on the same LAN or switch as the server. So you have full freedom about deciding how remote machines/users authenticate after they've negotiated and established the VPN tunnel. – DutchUncle Feb 23 '11 at 17:41 How to Enable VPN Passthrough - IPsec Firewall Port - Tom May 20, 2003 VPN and Port Forwarding on Windows 10 Pro - Microsoft

The VPN tunnel will allow remote computers to think that they are on the same LAN or switch as the server. So you have full freedom about deciding how remote machines/users authenticate after they've negotiated and established the VPN tunnel. – DutchUncle Feb 23 '11 at 17:41

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Oct 18, 2019

Port forwarding is a technique used to enable incoming internet connections to reach your device when using a VPN. It is necessary because most VPNs use an NAT firewall to stop users falling victim to malicious incoming connections. This is a useful security feature, but it is unfortunately unable to distinguish between incoming connections you don’t want and those that you do. OpenVPN - Wikipedia OpenVPN is open-source commercial software that implements virtual private network (VPN) techniques to create secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. It uses a custom security protocol that utilizes SSL/TLS for key exchange. It is capable of traversing network address translators (NATs) and firewalls. Solved: tcp port 443 for anyconnect - Cisco Community Mahesh, to establish a remote access SSL VPN to your ASA, yes TCP 443 will suffice throught the router. When you enable the certificate and webvpn on the outside interface as part of the VPN setup that tells the ASA to listen for the incoming SSL - so you don't technically "open" 443 on the ASA. OpenVPN Server with port forwarding | | What The Server