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Questions tagged [gre]

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

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UDP traffic DNAT doesn't return as expected

I'm looking for a solution with the following situation. There is server1 with public interface eth0 and IP 33.33.33.33 and GRE interface 10.10.10.1, GRE tunnel point to second server2 with public ...
Albert's user avatar
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GRE and QEMU and TAP

HOST SERVER ENO2 has Internal IP 192.168.55.128 and External IP 200.100.100.100 TAP0 has Internal IP 192.168.10.1 GRE1 has Internal IP 10.10.4.243 and External IP 165.100.100.100 VM SERVER eth1 has ...
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iptables - route traffic back to origin GRE interface

I'm struggling with iptables and packet marking.I have set up a system with 3 interfaces eno1: 192.168.0.100 gre1: 10.0.0.2 gre2: 10.0.0.6 and there is a local daemon running on eno1 port 1111 (nc -l -...
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Is it safe to use a Linux GRE tunnel with remote IP 0.0.0.0?

I have plenty of remote servers that have GRE tunnels to a single central server. Tunnel traffic is only from the remote servers to the central server. So for 50 remote servers, I usually have 50 GRE ...
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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 ...
Haswell's user avatar
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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 ...
BanHammer's user avatar
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Want to set GRE as the default network

I have configured 2 servers, SERVER A and SERVER B. (I have followed this tutorial: https://community.hetzner.com/tutorials/linux-setup-gre-tunnel) I have used SERVER A for GRE tunnel to SERVER B (...
Ishan k's user avatar
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send all traffic from Wiregurad to GRE Tunnel

I'm new in the Linux world so I don't know how to do the IPtable configs. my scenario is like this: I have a MikroTik and an UBUNTU Linux server. I created a GRE Tunnel between them and it works well. ...
Fredy's user avatar
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Connection Refused (GRE Tunnel - FiveM)

I am running a game server using Vultr. What I am trying to do is run the game server (backend server) through a GRE Tunnel. For this, I am using x4b.net for my GRE Tunnel. A few things to note: The ...
Andromeda's user avatar
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GRETAP over IPSEC ESP using ip-xfrm

I need to set up an IPSEC tunnel between two systems using ip xfrm commands, suitable for running ISIS over. Thanks to examples on the web, I am able to create either an XFRM or VTI link that works ...
Jeff Learman's user avatar
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Force UDP traffic to exit through the GRE Tunnel

I have an application that suffers from ddos. So we put it behind a filter that works on the basis of GRE. The filter works fine, but the application has a subapplication that answers to other ports ...
Joabe Meirelles's user avatar
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GRE tunnel. Port Forwarding with IPTables from VPS to Local Server not working

Dear ServerFault community, I have an OVH VPS with 3 public IPs (1.1.1.1, 2.2.2.2, 3.3.3.3) and I am trying to forward them individually, with one tunnel for each IP, to a server in my office (IP 5.5....
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Using OVH VPS as a shield to dedicated machine

I am having a few dedicated machines in a few hosting companies which either do not offer DDOS protection or their protection is awful. I've been contacting a few hosting companies and friends and got ...
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How can I setup and verify GRE tunnel pn ubuntu server?

In the scenario below, I'm going to configure SQUID and WCCP for web caching mechanism. Currently, WCCP is configured on router and squid is configured on UbuntuServer, but really I do not know ...
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Cisco GRE routing semantics to ip_gre

I am reading this article about setting up a GRE IP Tunnel: https://packetpushers.net/anatomy-of-gre-tunnels/ There's a section about creating a GRE tunnel interface on router A R1: interface ...
ohroblot's user avatar
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Connecting to server via VPN

There is a server with connection via VPN to it (using GRE protocol). I have got a problem to connect to this VPN from home network, because GRE is not allowed by provider. But I have got another work ...
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setting up gre tunnel on debian with tunnel source and tunnel destination

I am trying to setup a gre tunnel on debian to receive broadcast packets. I have the information for an interface ip address [10.16.2.4 255.255.255.192] tunnel source [10.16.0.2] tunnel destination [...
chllres's user avatar
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IP Binding Issue in using GRE Tunnel

I have a issue with tunneling and am having a hard time finding a solution. I have two servers, A: Host-Server being a sever with a single IP, and B: Main-Server being the server handling all our ...
NinjaDestroyer's user avatar
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Routing one machine's traffic through GRE tunnel to a remote NAT

I had to solve the following dilemma for a friend and thought I'd document how we did it here... Here's the situation: His home network 192.168.1.0/24 and it sits behind a Linux router that performs ...
Archie's user avatar
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GRE tunneling using Open vSwitch

I am trying to implement tunneling as described here with the following setup (without any success): ho1 is a host only interface. I want to connect Nested Guest 11 and Nested Guest 21. I have read ...
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Use working GRE tunnel as default on remote server

Purpose is to "protect" my backend dedicated server (B) using a front VPS (A) with a GRE tunnel and use the the new stablished interface (GRE1) as default on (B) in order not to leak the ...
safect's user avatar
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PPTP & GRE issue iptables/NAT

This is my first post and will try my best to add all the info. I am trying to accomplish something that i am not sure if it is supported, basically I have a firewall that is configure to allow ...
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How can I set up a point-to-point IPv6 GRE tunnel encrypted with ipsec between my Mikrotik CCR2004 router and a Linux host running Strongswan?

I need to encapsulate IPv4 in IPv6 for routing purposes. One end is a Linux box running quagga, and the other end is a Mikrotik CCR2004. How?
Falcon Momot's user avatar
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EdgeRouter Route Incoming Traffic to another Public Network/Server

I am curious if this is possible in theory? At my colo datacenter, I have a lot of public IP addresses (/21) on a 1GB circuit using an Edge Router 6P (not using BGP). I want to temporarily rent a ...
Marc Pope's user avatar
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Unable to setup a GRE tunnel between 2 servers

I currently have 2 servers: Server A: 2.2.2.2 Server B: 3.3.3.3 I want to create a GRE tunnel from server A to server B. I have ipforwarding enabled on server A: cat /proc/sys/net/ipv4/ip_forward 1 ...
user612795's user avatar
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A gre tunnel between Mikrotik and Cisco router

I really need your help I'm trying to connect a Mikrotik router with a Cisco router with GRE tunnel using Public IPS the problem is when I try to configure keep alive between both routers the tunnel ...
Ibrahim Salah's user avatar
3 votes
1 answer
2k views

Reading back Linux gre[tap] local/remote address

With iproute2 on Linux, gre/gretap interfaces are setup with ip link add, which for GRE needs remote and optionally local attributes specifying the endpoints. However, I can't find any way to read ...
R.. GitHub STOP HELPING ICE's user avatar
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Setting up a GRE tunnel on Windows Server 2019

I am trying to etablish an GRE tunnel to my Windows Server 2019, which seems easy enough. Although things get a bit complicated, as I want my applications to bind to the IP on the other side of the ...
mclc's user avatar
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preventing ipv6 packets from being generated when creating a gre tunnel

I have a veth device, each side of it is in a different network namespace on the same machine. I am creating a gretap tunnel over this veth. when setting the gretap device to up state I can see a lot ...
barisdad's user avatar
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Suppressing ICMP protocol 47 unreachable with userspace GRE implementation

For reasons that would require a lot of irrelevant context to explain, I'm handling GRE packets with a userspace process with a SOCK_RAW/IPPROTO_GRE socket. This is working fine, except that despite ...
R.. GitHub STOP HELPING ICE's user avatar
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Tunnel Linux traffic to Windows

I have two servers. Windows and Linux. Let's say Linux has the IP 1.2.3.4 and Windows 5.6.7.8. I want all traffic to be forwarded to windows as a tunnel. If I connect with 1.2.3.4:329 I want to ...
DGB Productions's user avatar
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Forwarding Home Game-Server through GRE Tunnel | Can't ping remote GRE IPs

I am having trouble routing my game-servers through GRE. I do not receive a ping from either side when pinging them. I can ping the local GRE interface; however, I cannot ping the remote GRE interface....
planetnation's user avatar
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Packets not getting forwarded on Centos7 between GRE tunnels

I'm have configured GRE tunnels between centos machines and corresponding routing tables on individual centos machines as shown in the image: I dont have enough reputation to post images Router1-----...
nguns's user avatar
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Interface bonding on GRE tunnel with nmcli

I have two Ubuntu server-based routers and I'd like to bond (in broadcast mode, since I only care about redundancy) a radio link (where the radio equipment is connected to an Ethernet port) and a LTE ...
RH6's user avatar
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gretap tunnel return traffic not being handled

I'm using iproute2 to add a GRE layer 2 tunnel with a vlan tag as shown below. ip link add name gre1 type gretap local 10.0.0.2 remote 8.8.8.8 ip link add name gre1.100 link gre1 type vlan proto 802....
Preston's user avatar
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How to route server_A's internet traffic through server_B using a GRE Tunnel?

I have two Linux servers. I want to use a GRE tunnel to route all internet traffic from ClientBox through a tunnel to GatewayBox, so that, to the rest of the internet, my ClientBox appears to be ...
socksilly's user avatar
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299 views

ACK packet lost in GRE tunnel for IPv6 in IPv4

At home (79.1.1.156), my ISP doesn’t provide IPv6 so I’m connecting my server to an external server (95.1.1.126) that has IPv6 access via a GRE tunnel, with this simple setup: ip tunnel add gretun ...
Christian Teijon's user avatar
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249 views

Seperate GRE tunnels cannot ping eachother

I have two systems that both tunnel to a core routing server. These systems both have a client address from the same /64 IPv6 prefix. From each client, I can ping the server with no problems and vice ...
Electromaster's user avatar
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1 answer
1k views

GRE Tunnel Dies in 1 direction

I have built a GRE tunnel over tap0 interface between 2 Centos-7 hosts. I've done this via the following: Host-A: 10.0.10.5 Host-B: 10.0.20.5 On host A: ip tunnel add tap0 mode gre remote 10.0.20....
johca's user avatar
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2 answers
2k views

Route incoming traffic through GRE tunnel

So I have a VPS and Dedi server both running Debian 9.9. 139.99.x.x: VPS 139.89.x.x: DEDI The Dedi server runs a game server but can't be directly accessible, I want to route all traffic through my ...
Martijn Kools's user avatar
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3 answers
2k views

GRE traffic not forwarded to local subnet

I have two debian machines in difference locations and want to enable routing between the two internal subnets via GRE. My general routing is already working, meaning any internal machine directs ...
Dero's user avatar
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Using iptables NAT to forward GRE tunnel

I have two hosts which need to have a GRE tunnel between them. In between the two I have a relay host which needs to perform NAT and forward the GRE traffic in either direction. grehostA --- ...
Rapsey's user avatar
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3 votes
3 answers
11k views

Allow GRE (IP protocol 47) over Linux router NAT for a subnet

I have network setup as shown below: The VPN server running is windows 2012 server default VPN, which uses GRE protocol. I am able to have VPN connection to that remote vpn server, from my intranet ...
Shyamkkhadka's user avatar
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1 answer
972 views

ERSPAN to IP on Centos host with multi interfaces on the same subnet

I have an interesting configuration and would like some help getting it to work. On a hardware network monitoring probe, i have 2 physical interfaces. mgmt is the management interface and mon1 is a ...
r-diggz's user avatar
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1 answer
978 views

Linux GRE Tunnel: Remote Address parameter

The Linux GRE tunnel as two parameters, local address and remote address. Suppose I have two routers, the left one is outside of a NAT and right one is inside NAT, then I want to create a GRE tunnel ...
Woody Wu's user avatar
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1 answer
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GRE perfomance issue on Linux

I got a strange GRE perfomance issue. The setup is shown bellow. [host1] --- GRE over Eth 1G --- [linux router] --- Eth 10G --- [host2] Iperf transfer rate host1>host2 reaches 950Mbps. It encreases ...
Veniamin's user avatar
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tc qdisc with GRE in openwrt

I'm trying to implement traffic control to GRE interface in an openwrt board. For this i followed below steps, Create GRE interface named gre1 in both tunnel end devices. Tested reachability with ...
Shihab Pullissery's user avatar
3 votes
1 answer
2k views

How to setup a GRE 3 host mesh without loops and forwards with OpenVSwitch?

I'm setting up a quite simple 3 host Proxmox (Debian) HA cluster. All VMs should be in the same subnet and when one fails over to another host inside the VM no reconfiguration should be required and ...
Jey DWork's user avatar
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2 answers
4k views

Packet loss in IpSec/GRE tunnel

This is my setup: +--------------------+ +-------------------+ +--------------------+ | Router B a +-----+ Router+Firewall C | | b Router D | | 10.10.10.1 -----------...
Matthias Wuttke's user avatar
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3k views

GRE Tunneling not working

i've been looking everywhere for a solution to this but have found really nothing. I was wondering if it is possible to forward ports such as 80 through an OpenVPN connection? I am using an OVH VPS ...
Purgatory's user avatar