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

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Openbsd set connect on PPTP server behind packet filter

I have firewall on OpenBSD use Packet Filter and behind him MS Windows server with PPTP server. I need allow connect this PPTP server from internet. I set in OpenBSD: net.inet.gre.allow=1 ...
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17 views

GRE Tunnel to Add IPs

Okay, here's the situation: server1 - my "main server" server2 - think of it like a proxy IP1 - main IP of server1 IP2 - main IP of server2 IP3 - additional IP of server2 I have, for years and ...
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1answer
123 views

Poor IPsec over GRE performances

I have set up an IPsec over GRE connection with a remote host, both are NetBSD 6.1 based. The "client" is connected to the Internet through a 400Mbps fiber connection. The "server" is located on a ...
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80 views

AWS VPC: Windows server 2012 R2 GRE tunneling to Linux based Peer VyOS

I am asking this question after having spent some time googling and trying to work out some issues which I have with a Windows GRE tunnel in our 2nd environment (amazon AWS VPC) to a router in our ...
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21 views

Add FQDN name in gre tunnel in Linux

Since aruba, cisco, etc all support add FQDN as gre tunnel's endpoint, can I do the same thing in linux via iproute2 or something else? Now, when I type a FQDN at ip tunnel, it just says that it's ...
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56 views

https connection can't established behind a gre tunnel

I have a network topological graph like this: Local box GateWay box +---------------+ +--------------------------+ |192.168.1.200 | -> |192.168.1.2 10.2.10.2 | ...
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47 views

Set up a GRE tunnel over multiple communication channels

I am in a situation where I would like to be able to set up a GRE tunnel running seamlessly over GPRS or Wifi in linux 2.6, preferring of course Wifi whenever available. So on one host I have two ...
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69 views

Set up transparent GRE/VPN to redirect all traffic to an External datacenter

I need to setup an existing server with multiple IPs (from OVH) to send all the traffic (through VPN or GRE tunnel) to an external server that has only 1 Public IP. I want to make it like every local ...
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93 views

Multicast on mGRE tunnels in Debian not working

I'm trying to setup multipoint GRE tunnels within 4 debian-based servers geographically distributed. Network configured, and hosts can see ping or ssh to each other by local IP. But I cannot get ...
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2answers
473 views

How to route outbound traffic for a particular destination IP address to GRE Tunnel in CentOS?

Hello I am trying to configure a network like this network diagram :- Well I have to create a GRE Tunnel at my alpha server and route some particular traffic to GRE Tunnel.I want to do the configs ...
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57 views

GRE Tunnel Collapsing in One Direction

This is a related question to another thread I posted. I'm having an issue where my GRE tunnel is collapsing in one direction, but can be reopened by ping the other server using the GRE Interface. ...
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1answer
301 views

Multicraft: Port Forwarding through a GRE Tunnel

For the past week I've been attempting to protect a server from DOS attacks by utilizing a GRE tunnel from a VPS to a dedicated machine without much success. Visual: User --> VPS --> Dedicated ...
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65 views

Public IP not responding because routing table…?

Fixed with: /etc/iproute2/rt_tables 1 tble_eth0 /etc/sysconfig/network-scripts/route-eth0 104.000.64.0/18 dev eth0 src 104.000.65.38 table tble_eth0 default via 104.000.64.1 dev eth0 src ...
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1answer
126 views

Remote end of IPSec transport is 'permenantly glued' to loopback after some messing around with GRE

So, I have managed to get IPSec transport over ESP between two hosts using racoon: the 'local' host, 1.1.1.1, and the remote, 2.2.2.2. It only worked for ICMP (other traffic ignored the SA), but ...
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1answer
258 views

TLS-intolerant sites suddenly not working

About 2 weeks ago users started reporting that they were unable to access two https-only sites. When I inspected these sites I found they were completely intolerant to TLS. In order to connect, SSL3 ...
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1answer
276 views

GRE Tunnel in CentOS

How to create a GRE Tunnel in CentOS pointing all connections to server A for the server B? I have a public server with DDoS protection and need to use this as a firewall to filter acess to the other ...
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203 views

Debian forward through NAT EOIP GRE

eth0 = WAN eth1 = LAN to forward any port through nat I use e.g: iptables -t nat -A PREROUTING -p tcp -d 79.188.31.34 --dport 8291 -j DNAT --to-destination 192.168.0.36:8291 and it works, but ...
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209 views

Using my IPs on OVH server via GRE

I can't route my IPs into a OVH server, can you help me to find the problem? Mikrotik GRE IP: 192.168.55.10 OVH Server GRE IP: 192.168.55.20 GRE iface name: ali1_fr1-ovz1 IP to route from Mikrotik to ...
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38 views

GRE Routing Troubles

I will try to be concise and fully explain my situation here. I was handed a project after my client had a falling out with a previous developer. We had a defunct copy of his system, and I am trying ...
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104 views

Listening “through” GRE Tunnel

Currently I'm looking to learn about using GRE Tunnels and I have the following scheme: Server1 (200.1.2.3) ----> Server2 (190.1.2.3) Both servers have public IPs Then I've setup a GRE Tunnel with ...
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1answer
795 views

WCCP and Squid, and Tunnels

I'm trying to configure WCCP + Squid with the following documentation: http://www.crypt.gen.nz/papers/cisco_squid_wccp.html I have a cisco switch, a test client, and a squid proxy server. I think ...
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1answer
155 views

How is my GRE-Tunneled packet being routed? [closed]

I'm trying to figure out exactly what is happening when I create a GRE tunnel. My network looks like this (-> means directly connected): Computer A (eth0: 10.0.1.1) -> (eth0: 10.0.1.2) Router B ...
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1answer
4k views

Transparent Ethernet over GRE not forwarding traffic

I am running on Linux 2.6.30.9 and have been trying to setup a transparent ethernet over GRE tunnel. The network topology used is as follows: I want to bridge PC1 and PC2 using Transparent Ethernet ...
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982 views

IP/GRE compiled in kernel but gre0 interface doesnt exist

Im trying to create IP over GRE tunnel but i get No such device: ip tunnel add gre0 mode gre remote 192.168.152.22 local 192.168.152.21 ttl 255 ioctl: No such device I have compiled GRE support in ...
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755 views

DMVPN and OSPF (two tunnels dynamic routing)

please help me to resolve the problem with routing between dmvpn GRE tunnels. I've got a DMVPN HUB and SPOKE topology. HUB has public ip address in internet. SPOKE has two ISPs for redundancy. I've ...
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267 views

Using public interfaces on a server connected through a GRE tunnel

I'm pretty new to networking so please forgive any terminology mistakes. I have 2 servers connected with a GRE tunnel. Server1 (10.0.0.1) ----> Server2 (10.0.0.2) I want to be able to bind to the ...
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1k views

GRE keepalive with Linux and RouterOS

I have a Linux host and couple of routerboadrs. I created a GRE tunnel, but Linux does not answer keepalive packages. Then router mark gre connection as unreachable, so I cant send to Linux host from ...
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61 views

GRE tunnel / Route traffic based on which domain the user is trying to access

Imagine this kind of setup. 5 servers. 1 server will be the "front-end", all the traffic has to go through it first before going to the 4 other servers. I don't want people to know the IPs of the ...
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1answer
2k views

GRE: read from PTY failed error when connecting multiple clients to PPTP

I have just installed a pptp server and now I can make it work. The problem is, it can only be connected to by one client. How do I set it up so that it will allow multiple users? Here is the error ...
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1answer
574 views

How GRE traffic finds way after arrive GRE remote end points (in open vswitch)?

I'm quite new to both network and open vswitch, I'm not sure whether this question is more relevant to open vswitch(ovs) or gre. belows are ovs settint commands. There are two hosts. Each host has ...
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284 views

GRE tunneling in vmware vsphere guest [closed]

Is it possible to make a GRE tunnel between a dedicated linux machine and a vmware vsphere guest VM (running debian wheezy)?
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348 views

Ubuntu GRE local ip address, wan ip of router, or ip of ubuntu server

I have an ubuntu server behind a router that I am configuring to have a GRE tunnel to another remote device across the interwebs. in the config, I add the line: pre-up iptunnel add tun1 mode gre ...
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1answer
858 views

openvswitch: connecting two virtual private networks on two different machines with gre/ipsec

Here is the setup: We have a hardware (server) that presents a service to the customer (or "outside world", if you so will). Internally, the services and functions are distributed over several virtual ...
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1answer
451 views

How to troubleshoot GRE tunnel issues?

I commonly run into issues where a GRE tunnel (CentOS server to server, not router based) works and pings fine from both ends but the IP / Range being tunneled does not function. This almost always ...
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222 views

How to check for GRE Tunnels [closed]

Is there a way to check for GRE Tunnels? I've heard spammers will use GRE tunnels to send mail from a central machine out of another and would like to check for possible GRE tunnels.
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Why two addresses in configuring a GRE tunnel?

As I can find in this support document, in order to configure a GRE tunnel between two routers R1 and R2, I issue the following sets of commands (mtu and mss omitted), R1 R1(config)# interface ...
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1answer
470 views

Redirect SSH traffic through GRE tunnel

I'm trying to redirect all local connections with destination matchs port 22 to specified tunnel using iptables MARK, but, something is going wrong. 1.1.1.1 my public address 2.2.2.2 tunnel public ...
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1answer
2k views

How to force certain traffic through GRE tunnel?

Here's what I do. Server (public internet is 222.x.x.x): echo 'net.ipv4.ip_forward=1' >> /etc/sysctl.conf sysctl -p iptunnel add gre1 mode gre local 222.x.x.x remote 115.x.x.x ttl 255 ...
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979 views

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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858 views

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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8k views

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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1answer
2k views

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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2answers
425 views

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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1answer
3k views

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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2k views

What's the difference between GRE and IPIP tunnel?

And which one is better for connecting two linux machines?
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492 views

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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320 views

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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356 views

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 ...
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2k views

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 ...