Questions tagged [gre]

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

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Centos GRE Tunnel

I have two servers. Centos 7 installed on both. Main Server: 45.x.x.yy/32 Slave Server: 185.x.x.yy/32 I want to use the ip address of the Slave Server on the master server by establishing a GRE Tunnel ...
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Pfsense GRE to Proxmox Openvirtualswitch gateway not going up

So, I run pfsense on Hetzner Cloud and proxmox on Hetzner Cloud. Both are VMs. The Hetzner network is very restricted. I found a solution: GRE tunnels. The following setup works: pve machine = 10.0.0....
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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 ...
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GRE Tunnel subnet /29

I watched this tutorial: https://www.lowendtalk.com/discussion/156850/howto-tunnel-ddos-protected-ovh-ip-to-vms-in-other-datacenter And I have problems with the GRE tunnel, I created a VPS on server 2 ...
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How to route traffic from nat interface through GRE Tunnel? - Debian

I have these two dedicated servers, let's call them A and B; I've created a GRE tunnel between the two and it works as supposed to. On server A, I also have a NAT interface configured and it works but ...
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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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49 views

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 ...
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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?
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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 ...
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Tunnel keep-alive issue between Cisco and Mik 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 ...
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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 ...
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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 ...
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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 ...
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Docker container with GRE network incorrect checksum

I have a server with docker, whose containers connect to the internet via a GRE tunnel. My configuration looks like this (bridge network): { "Subnet": "10.0.0.128/25", &...
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213 views

Docker network bridge GRE tunnel

I am currently trying to setup a network docker bridge with a GRE tunnel. I have setup the GRE tunnel fine and the GRE tunnel is working, however, whenever I tried to use docker with it, it wouldn't ...
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Cannot Locate IPIP Tunnel With Specific Remote IP

I have a dedicated machine running on Ubuntu 20.04 with kernel 5.4.0-52-generic. I use something called Docker Gen (running this configuration) to setup IPIP tunnels when a Docker container starts and ...
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GRE Tunnel - Trasfer /30 subnet to remote KVM host

Tutorial used: click here Commands used both servers: Server 1 ip tunnel add gre1 mode gre remote 9.176.110.209 local 212.188.100.58 ttl 255 ip link set gre1 up ip route add 212.188.103.64/30 dev gre1 ...
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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 ...
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191 views

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 ...
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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 ...
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167 views

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 ...
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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....
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298 views

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-----...
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271 views

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 ...
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174 views

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....
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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 ...
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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 ...
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42 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 ...
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353 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....
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587 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 ...
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546 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 ...
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2k views

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 --- ...
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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 ...
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458 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 ...
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489 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 ...
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236 views

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 ...
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372 views

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 ...
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1k 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 ...
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2answers
3k views

Packet loss in IpSec/GRE tunnel

This is my setup: +--------------------+ +-------------------+ +--------------------+ | Router B a +-----+ Router+Firewall C | | b Router D | | 10.10.10.1 -----------...
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2k 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 ...
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1answer
1k views

Get IP over DHCP for GRE-tunnel

I need to create a GRE tunnel from a client to a server. This is my setup. Setup: ________________________________ _________________________________ ______________________________ |Server ...
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1answer
1k views

Bonding over OpenVPN, for fault tolerance

I have two OpenVPN server, and two machines connecting to them. Server 1 openvpn address: 10.158.1.1 Server 2 openvpn address: 10.158.2.1 Machine 1 has address 10.158.1.11 on server 1, 10.158.2.11 ...
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1answer
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iptables SNAT not working for GRE packets

I am trying to apply SNAT to a PPTP client. The TCP/1723 packets are being SNATed properly but not the GRE ones. Can anyone spot what's wrong? I have the following iptables configuration: $ sudo ...
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1answer
278 views

Public to Public IP GRE

I've managed to setup a GRE tunnel between two servers using BuyVM's very great guide (also used a guide via ServerFault) It simply works. I can ping internally So. To get into perspective: A = 1.1....
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546 views

Nat over GRE using IPsec VPN tunnel

I’m working on implementing VPN tunnel IPSec GRE from Natted Linux box with Ubuntu. I have found a very useful article, related to IPSec-GRE tunnel behind NAT, made with Cisco routers. I have ...
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811 views

L2TPv3 tunnel private IPs not working

I'm trying to setup L2TPv3 tunnel between 2 servers - CentOS 7 and Ubuntu 16 On CentOS 7 end I have the following: ip l2tp add tunnel tunnel_id 6000 peer_tunnel_id 5000 encap udp local LOCAL_IP ...
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3k views

IPSEC over GRE tunnel on PFSENSE

I have two PFsense routers xxx.xxx.xxx.28 and xxx.xxx.xxx.27 and local networks behind them 192.168.110.0/24 and 192.168.111.0/24. The point is to set up GRE tunnel with IPSEC between these networks. ...
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361 views

GRE With scaleway

i'm having some problem here to create a GRE tunneling, it' theoretically simple, i have 2 clouds, one, with DDoS Protection, and another, without that. In my first cloud, it have DDoS, hosted in OVH, ...
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PPTP Passthrough Centos 7/Firewalld router to Windows Server

I have a Centos 7 server running firewalld to allow public services to access internal services on a separate VLAN (dual NICs). I imported a Windows VM but I do not know what rules I need to put in ...