Port forward GRE and PPTP using IPtables

GRE is a protocol, not a port. (A lot of people say "My router isn't blocking any ports" but that's irrelevant.) Your router needs to understand how that protocol works. In particular, assuming that you're using NAT (Network Address Translation), the router will need to replace your private IP address with its public IP address in the outbound IP PROTOCOL 47 (GRE) Solutions | Experts Exchange The problem I'm having is understanding what this Protocol 47 (GRE) is, there does appear to be some conflicting views on this as I've found so far. As I understand it, Protocol 47 is a protocol and not port, so when setting up a new service on my firewall I don't have the option of GRE … how do I set up GRE Protocol 47 after I forward my VPN to port

PPTP clients cannot connect to a PPTP server that has

Solved: GRE Tunnel through firewall performing - Cisco Jun 15, 2020 What is Generic Routing Encapsulation (GRE)? - Definition Generic Routing Encapsulation: Developed by Cisco Systems, Generic Routing Encapsulation (GRE) is a tunneling protocol that makes it possible to encapsulate, over an Internet Protocol network, a large variety of network layer protocols inside virtual point-to-point links. GRE is defined by RFC 2784 and as a tunneling protocol, carries OSI

Oct 07, 2018

The GRE header indicates the payload protocol type via an EtherType in the protocol type field, and the source port field in the UDP header may be used to provide additional entropy. A GRE-in-UDP tunnel offers the possibility of better performance for load-balancing GRE traffic in transit networks using existing Equal- Cost Multipath (ECMP Clint Boessen's Blog: Testing GRE Protocol with PPTP VPN