Generic Routing Encapsulation (GRE) is a tunneling protocol, developed by Cisco.

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Cannot Delete GRE Tunnel

I am configuring a GRE tunnel in Linux 2.6.26 and I've been facing a very strange problem for which I could not find any solution. I have created a GRE tunnel called gre0, but no matter what I do, I ...
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Routing subnet over GRE tunnel

Im trying to configure a GRE over IPSec connection between two subnets. The IPSec tunnel is opened and now I want to add a GRE tunnel over it: ip tunnel add GRE01 mode gre remote 10.244.0.1 local ...
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Does a router have to explicitly support GRE in order to pass those connections?

I have replaced a mess of Cisco routers with a single Dell PowerConnect 6224. These routers serve (and served) public IPs to clients, and just acted as routers to the upstream provider. Prior to the ...
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How to enable debug logging for GRE?

How to enable debug logging for module ip_gre on linux 2.6?
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GRE over IPSec behind FW

I have a checkpoint S-Box which is a gateway for network 192.168.0.0/24. Internal IP is 192.168.0.1. On the S-Box configured static VPN tunnel with local IP 10.x.x.x and remote 10.y.y.y. I need to ...
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Multiple GRE NAT router

Does there exist a router that supports multiple GRE connections over NAT? Im currently running pfSense, and it only supports 1 at a time. I understand why, its just a drag as there are multiple ...
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How to setup an IPSec / GRE tunnel on Windows Server 2008

I have a Windows Server 2008 that has a single network interface configured with a public IP address. My business partner has a private network. From my server, I need to access all the devices on his ...