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

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Linux/Vyatta failover with GRE and OSPF/BGP

I have strange problem with routing failover in scenario: I'm trying do this failover via ospf or bgp, in both happens the same strange behavior with tunnels: For 192.7.0.0 TUN providing default route ...
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OpenNHRP configuration without IPsec

I'm attempting to use OpenNHRP on a linux box to connect with a Cisco Router. I want to allow GRE tunnels from the linux box to the Cisco router dynamically, but I'm not implementing DMVPN on the ...
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PPTP connection fails with errors 800/806

I've got a client (Server 2008 R2) that won't connect to our production environment PPTP VPN server (Server 2003, running RRAS). The server is behind a firewall that has TCP1723 open as well as GRE. ...
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Setting up a GRE tunnel on a Cisco ASA 5505 [duplicate]

Possible Duplicate: Set up a GRE tunnel with Cisco PIX-506 v6.3 I'm trying to establish one half of a GRE tunnel, the other being configured by my service provider. I have a Cisco ASA 5505 ...
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using a gre tunnel as default route

I have two private networks (A, B) that connects via another company's private network (C). Network A has internet access. I want to make a tunnel between B and A that goes through C. Then network B ...
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Set up a GRE tunnel with Cisco PIX-506 v6.3

I'm trying to establish one half of a GRE tunnel, the other being configured by my service provider. I have a Cisco PIX-506-E running Firewall version 6.3(5). Provider Router Public IP: 8.8.8.8 My ...
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Multiple GRE tunnels on the same host, only one routes incoming packets

I'm having a routing problem on CentOS 6.2 (kernel 2.6.32-220) Here's the setup: One host is on my local network. It's talking to two nearly identical hosts at a remote location. The two remote ...
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What's the difference between GRE and IPIP tunnel?

And which one is better for connecting two linux machines?
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how to forward all traffic over a GRE over IPsec VPN on cisco routers?

i have 2 cisco ISR 2821 and 2811 and they are connected over a site to site GRE over IPsec vpn. my question is that, how can i forward all traffic or web traffic to the other router? thanks
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How to forward all GRE traffic to a particular network interface?

I want to forward all GRE traffic (IP protocol 47) coming on eth2 to br0 on my machine. How can I do that?
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GRE debug: “adding 0 encap bytes”?

What this debug message actually means? Shouldn't encapsulation add 24 extra bytes or not? For what reason encapsulation is not adding bytes to original packet in this debug message? Dec 28 23:45:39....
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GRE Tunnel between Linux server and XP client

I want to set up a simple unencrypted tunnel between a linux-server (running SLES9) and a client (running XP SP3). The reason for this is that there are many network devices in between and the client ...
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Gre Tunnel Cisco Linux traffic forwarding

I setup a gre tunnel a cisco router and a Linux machine, the tunnel interface in the Linux box named pic. Well i have to forward traffic coming from cisco through the Linux box. the rules i've set in ...
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GRE Encapsulation and Multicast

How does GRE Encapsulation actually send multicast traffic? My CISCO textbook tells me that the multicast packet is carried inside a unicast packet. My understanding is: Multicast packet, say for ...
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cannot ping through gre tunnel

This question has been merged I have 4 machines machine 1 have ip address 172.13.0.40/24 machine 2 have two ip address 172.13.0.1/24 and 172.12.0.1/24 machine 3 have two ip address 172.12.0.50/24 ...
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Is it possible to find out the make/model of the router remotely?

First a little background. My company is renting some servers at the Terremark cloud. As we want to connect our servers to the infrastructure of a mobile carrier in order to restrict our end users to ...
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GRE Tunnel over IPsec with Loopback

I'm having a really hard time trying to estabilish a VPN connection using a GRE over IPsec tunnel. The problem is that it involves some sort of "loopback" connection which I don't understand -- let ...
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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 10....
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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 ...