Configuring IPsec Virtual Private Networks
Which ports do you need to open on a firewall to allow L2TP over IPSec To allow Internet Key Exchange (IKE), open UDP 500. To allow IPSec Network Address Translation (NAT-T) open UDP 5500. To allow L2TP traffic, open UDP 1701. ipsec vpn ports? - Cisco Community Re: ipsec vpn ports? Most likely not possible on an ASDL modem and since he is doing NAT the solution would be as stated above to use NAT-T. Therefore pushing phase 2 up to udp/4500. What is IPSec VPN - SSL Vs IPSec VPN - June 2020
More often than not, IPSec VPN ports are usually open in the firewall. If it is not, you can make it work by opening UDP port 500. This allows ISAKEP traffic to get forwarded through your firewalls. It also permits IP protocol IDs 50 to allow ESP traffic and 51 to allow AH traffic.
I have tried to test these VPN connections from a Windows box located elsewhere, and have found out that with Windows' VPN client I can only set up the type of VPN (along with auth factors etc) but not server port when it comes to L2TP/IPsec connections.
SRX Series,vSRX. IPsec VPN Overview, IPsec VPN Topologies on SRX Series Devices, Comparison of Policy-Based VPNs and Route-Based VPNs, Understanding IKE and IPsec Packet Processing, Understanding Phase 1 of IKE Tunnel Negotiation, Understanding Phase 2 of IKE Tunnel Negotiation, Supported IPsec and IKE Standards, Understanding Distributed VPNs in SRX Series Services Gateways …
L2TP stands for Layer 2 Tunneling Protocol, and it doesn’t provide any encryption by itself. L2TP VPN usually uses an authentication protocol, IPSec (Internet Protocol Security), for strong encryption and authentication, which gives it an ultimate edge on some other most used protocols like PPTP. The L2TP protocol uses UDP ports 1701. [ScreenOS] What ports are used for a Virtual Private Ports need to be open on the firewall to allow IPSec or VPN through. Solution: Internet Protocol Security (IPSec) uses IP protocol 50 for Encapsulated Security Protocol (ESP), IP protocol 51 for Authentication Header (AH), and UDP port 500 for IKE Phase 1 negotiation and Phase 2 negotiations. SonicWall IKE VPN negotiations, UDP Ports and NAT