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I am new member of Network Engineering site!

These days I am interested in GRE tunneling.

I know that GRE is developed by CISCO and many routers produced by CISCO and Juniper support GRE tunneling.

But I want to know other routers or firewalls support GRE tunneling.

How can I know whether some routers support GRE if there's no mention in product specification without testing by myself?

I also wonder that GRE is standard or used generally in network industry or not.

Thanks.

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  • As GRE is a Cisco proprietary protocol, you're not likely to find equipment from another vendor which supports it. Can you please provide more information on what it is you're trying to achieve?
    – OzNetNerd
    Nov 27 '15 at 0:38
  • Thanks for comment, I want to construct GRE tunneling between my company's firewall to AWS cloud server. Nov 27 '15 at 1:17
  • And also want know whether many non-cisco routers(include mine) support GRE or not. Nov 27 '15 at 1:25
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    As mentioned above, GRE is Cisco proprietary so I doubt you will find GRE available in any vendor's equipment apart from Cisco's. Is there a reason why you want to use GRE specifically? After all, GRE tunnels are not encrypted so if you're wanting to connect your company to AWS, GRE is definitely not a good idea. What model firewall do you have? Chances are if it supports IPSEC you'll be able to create a secure (encrypted) tunnel to AWS. See this link for more information - docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_VPN.html
    – OzNetNerd
    Nov 27 '15 at 2:29
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    I can't definitively say that no vendors' equipment can use GRE or have a similar feature, but I could imagine one of the reasons why Cisco made GRE proprietary as opposed to an open standard is so that it is a selling point for them. Similar to the way EIGRP is (mostly) proprietary - packetpushers.net/why-is-cisco-bothering-with-open-eigrp - I would not call GRE a VPN because there is no encryption involved. It is a clear text tunnel. As mentioned in my previous reply, you should look at using an IPSec tunnel as IPSec is not proprietary and it is encrypted.
    – OzNetNerd
    Nov 27 '15 at 5:55
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Although GRE is developed by Cisco, it doesn't mean that other vendors don't support it. It's became kinda standard in the industry and I have not seen any single vendor who doesn't support it, whether Juniper, Check Point, Fortinet, etc.... And it's also pretty simple to implement on any Linux distribution.

I'd rather getting in contact with the Sales/Technical team of the vendor and ask whether it is supported.

As mentioned, it's generally used in Network industry.

Regards, Mohammad Moghaddas

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  • Thanks for your answer, It really helped me. I didn't know that GRE is generally used in Network Industry. I am trying to contact to my firewall's vendor to get technical support. Thanks again!! Nov 30 '15 at 0:21
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This is a rather old thread, but I noticed it when googling "Why doesn't Palo Alto support termination of GRE?"

Add Barracuda NGFW and Cisco's latest FirePower 39xx series NGFW to that list of firewalls that support GRE termination (some older iOS versions only supported IPSEC despite GRE being a Cisco protocol). GRE is often used to forward traffic to another network or cloud platform for infrastructure (IaaS such as Azure and AWS) and Security (SECaaS such as Zscaler).

In the case of Zscaler it does actually serve as a VPN, and in addition to securing the endpoint, can use multi-factor authentication to authenticate the client, and provide access to secure applications (not networks), via an on-demand encrypted tunnel.

If used correctly GRE is a great security tool with a bunch of flexibility and performance benefits over IPSEC.

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