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Questions tagged [gre]

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

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

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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 log that is thrown after the second user tries to…
reikyoushin
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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 machines (of different roles). We use kvm for…
lImbus
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How to check for GRE Tunnels

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.
Tiffany Walker
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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 Tunnel1 R1(config-if)# ip address 172.16.1.1…
Masroor
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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 will use A as default route for internet…
Sirber
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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 PIX Public IP: 7.7.7.7 Provider Tunnel Address:…
Antonius Bloch
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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 RIP, has address 224.0.0.9. GRE takes that, wraps it…
Edgar Velasquez Lim
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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 and 172.17.0.1/24 machine 4 have ip address…
sanketmlad
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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 10.244.245.32 ttl 255 ip link set GRE01 up ip addr…
eMgz
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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 replacement, a customer had a VPN appliance that…
David Mackintosh
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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 create a GRE tunnel with local 10.z.z.z and remote…
Boris
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How does GRE interface route packet to remote endpoint

I have the following topology which I configured to run a GRE tunnel between my Desktop and the wireless router. On the PC: ip link add l2gre0 type gretap remote 192.168.0.103 local 192.168.0.10 On the Router: ip link add l2gre0 type gretap remote…
Haswell
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GRE tunnel issue

I have 2 linux servers. I want to use server 1 ip for server 2 as a ddos protection, I have followed a tutorial online which works quite good but there is a small issue. While trying to do curl server1ip inside server 2 it gives me error connection…
Mr Pro
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How can I route traffic back through the interface it came through for Docker

Currently I have a setup with 1 physical NIC with a public IP address, a standard docker environment and a GRE tunnel & bridge. If I run a container on a port, lets say 80, I'll be able to connect directly to the container via the public IP…
BanHammer
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Exceed routing limit of 255 on Debian (any Kernel version)

I want to setup more than 255 GRE tunnels between 1 server and about "6000 other servers/aka proxies", method used is: sudo ip tunnel add gre1 mode gre local 149.5.175.220 remote 5.182.37.41 ttl 255 sudo ip addr add 10.0.0.2/30 dev gre1 sudo echo…
AlbertBrenaman
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