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GRE tunnel behind NAT

dnwkdnwk Member
in Help

I'm trying to run a GRE tunnel from my home server to a VPS. I'm trying to figure out if that's possible. I could do port forwarding at home and my IP doesn't change. But I can't seem to find if GRE will work for port forwarding and which port to forward.

Comments

  • yoursunnyyoursunny Member, IPv6 Advocate
    edited March 2021

    GRE runs in top of IPv4.
    It uses neither TCP nor UDP.
    Therefore, you should forward IP proto 47.
    http://www.networksorcery.com/enp/protocol/gre.htm

    If you have OpenWrt, simply type "47" into the protocol selection box, and the system will recognize GRE.

  • dnwkdnwk Member

    @yoursunny said:
    GRE runs in top of IPv4.
    It uses neither TCP nor UDP.
    Therefore, you should forward IP proto 47.
    http://www.networksorcery.com/enp/protocol/gre.htm

    If you have OpenWrt, simply type "47" into the protocol selection box, and the system will recognize GRE.

    Thanks you. No wonder why I can't find GRE in OpenWRT's port forwarding. I guess you need to enter the number 47.

  • SplitIceSplitIce Member, Host Rep
    edited March 2021

    Yes @yoursunny is correct. GRE is ip proto 47.

    Most commercial retail routers don't have the option, but DMZ often forwards all protocols (depends how it's implemented).

  • CConnerCConner Member, Host Rep

    You could always try and using PFSense as your router. Has full support for GRE built in.

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