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Questions tagged [gre]

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

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How to exclude gre tunnel from going through OpenVPN connection by default?

I'm bit at a loss here as I don't know how to do this. I have two servers connected via gre tunnel (A: 192.168.168.1, B: 192.168.168.2). Server B is running a TeamSpeak server which I connect to via ...
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56 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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45 views

GRE(IPv6) over IPSec(IPv4) - How to convince a Fortigate 60D to accept IPv6 addresses for the “system” interface?

Folks, for the life of me, I can't figure out how to convince a Fortigate 60D to accept IPv6 addresses as GRE Tunnel endpoints. This is on a Fortigate 60D running FortiOS 6.0.3. The network setup ...
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2answers
378 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 ...
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1answer
62 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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38 views

Openvswitch does not forward transit GRE traffic.

Seems to be that openvswitch on my KVM host doesn't forward transit GRE packets. I have switch acting as source of ERSPAN traffic, directly connected to the host. This traffic is just unidirectional ...
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1answer
219 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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42 views

How can i move all the network traffic on the backend over the gre tunnel?

i have a gre tunnel with a frontend and a backend. I need to move all the backend traffic over the gre tunnel in order to reach all applications of the backend via the frontend IP. Can you help me? ...
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96 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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166 views

Connecting IP GRE and EoGRE tunnel in the same linux host

Is there a way to forward the payload of a GRE traffic to a different EoGRE tunnel on the same Linux host ? Host A (GRE (IP/GRE/IP)) <—> (GRE (IP/GRE/IP)) Host B (EoGRE(IP/Ethernet/GRE/IP) <...
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1answer
250 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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481 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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1answer
988 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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1answer
675 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
701 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
814 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
857 views

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
172 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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372 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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1answer
559 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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1answer
2k 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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238 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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1answer
2k views

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 ...
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1answer
413 views

Virtualize using IPs under GRE Tunnel (or NAT?)

Well, this is the situation I am experiencing: I've got a dedicated server from OVH, and a dedicated server from another company, since the maximum RAM for the OVH server (GAME category) is 64Gb of ...
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462 views

Proxmox NAT with GRE tunnel as outside interface

End goal (ASCII Diagram) WAN->Router->Server->GRE Tunnel->VM network->VM #1, etc. I should explain some things first. I have a server running Proxmox (Debian 8.7 x64). It's ...
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1answer
1k views

GRE tunnel TTL number

Here is the setting on server A: iface serverA_gre0 inet tunnel address 172.24.0.85 mode gre endpoint x.x.x.x dstaddr 172.24.0.86 netmask 255.255.255.252 ...
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170 views

Is there a load balancer that will terminate a GRE tunnel?

I have a network in which several site routers send portions of their traffic to an inspection device via GRE tunnel. I am beginning to exceed the capacity of the inspection device. I could always ...
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1answer
232 views

Why am i receiving so many unsolicited GRE packets?

My (linux) server has some fairly simple iptables rules. iptables -A INPUT -p icmp -j ACCEPT iptables -A INPUT -m state --state ESTABLISHED -j ACCEPT iptables -A INPUT -m tcp -p tcp --dport ssh -j ...
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3answers
263 views

Gre tunnel routing Public IPs between two servers

I want to route public IPs from server A and use them on server B. I created the GRE tunnel and it works. I then setup a route on server A in the following way: (public IP not actual IP) 192.168.11....
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1answer
2k views

MikroTik GRE over IPSec

I'm trying to establish a GRE over IPSec tunnel between two MikroTik devices. Everything seems to work yet when I sniff the WAN interface I can clearly see the GRE packets which theoretically I ...
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1answer
290 views

pptp gre in csf firewall

i have a senior problem. when i want to connecting a pptp over a tap adaptor or a pptp connection have get disconnected and get this errors on messages logs: linux pptpd[20275]: GRE: read(fd=7,buffer=...
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428 views

GRE protocol type for Ethernet over GRE?

For a IP over GRE tunnel, as defined by the RFC 2784, the "protocol" field is filled with 0x0800 (defined as ETH_P_IP in the Linux kernel according to this source http://www.scs.stanford.edu/histar/...
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1k views

Reverse proxy for DoS / DDoS protection

after i search how to protect my website host server using GRE tunnels, some friends of this forum give me a tip to use Reverse Proxy that would be better. But i don't found any guide on how to ...
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1answer
679 views

Linux GRE keep alive

What are possibilities in Linux kernel (?) to work with Cisco endpoint encorporating GRE keep-alives? We have GRE IPsec tunnel set up with another company. We would like to have backup tunnel which ...
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0answers
156 views

What could cause racoonctl to show a Phase2 count higher than the number of ports racoon is listening on?

In my setup I have some EC2 instances in different regions linked by GRE tunnels, using ISAKMP via racoon. This setup is inherited, so bear with me if I fumble with terminology. Sometimes I get weird ...
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1answer
823 views

Load balancing between two (or more) GRE tunnels

I have a hosted service (think zScaler™) that is having me send my traffic to it via GRE tunnels. I am given two appliances and want to load balance my traffic between the two tunnels. I could ...
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779 views

Ethernet over GRE bridging - Proxmox

I'm trying to install two proxmox on Online.net server's, and I just realized that their RPN feature doesn't work at all like the OVH vRacks. Since I need the different VM's on both hypervisors to be ...
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123 views

Cisco 1941 EIGRP UP DOWN

We have two cisco routers 1841 and 1941. The 1841 keeps generating "holding time expired" and "interface goodbye recieved" about its neighbor the 1941. The VPN IPSec protocol seems to stay up. ...
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1answer
938 views

Amazon Linux - iptables NAT rules not matching GRE traffic

I'm trying to prototype something in AWS VPC/EC2, but I can't get my NAT rules to work. I have the following setup (all instances running the Amazon Linux AMI): GRE Tunnel between instances 10.0.0.10 ...
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138 views

internet access for system over multiple hops of ipsec using GRE and OSPF

I have the following setup: linux client @ 172.16.10.68 linux gateway @ 172.16.10.69, ipsec tunnel to aws box #1, gre tunnel 10.254.0.0/30 aws box #1, ipsec tunnel from linux gw, ipsec tunnel to ...
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1answer
279 views

GRE - overlay network

I am renting a set of dedicated servers, and they only have a single interface to internet. However, for a lot of use cases, I would like my servers to communicate through a private IP network. For ...
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0answers
127 views

IP Tables forwarding tun0 over gre1 (OpenVPN)

I haven't found a very descriptive thread (and sorry if there is one in existence - in my several hours of searching I've found nothing to my specific situation). My main issue here is getting my ...
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1answer
856 views

Iptables not routing GRE protocol

First things first, there might be a few English errors, considering it's not my native language. I'm having a problem with VPN(GRE protocol) passing through Iptables. I've done this at least a dozen ...
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1answer
304 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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1answer
1k 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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1answer
355 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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2answers
4k 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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183 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. I'...
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1answer
2k 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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1answer
146 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 104.000.65....