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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.

131 questions
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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 RAM, and I need more, I'd like to make a GRE tunnel…
Matthew
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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 stand up two inspection devices to divide and…
loadBalanced
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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 shouldn't be able to see. I've spent a few days on this…
john.mill
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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 should be active when main one dies. So they enable…
unhit
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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 output from racoonctl -ll show-sa isakmp (pardon…
2rs2ts
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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 and 10.1.0.10 instance 10.0.0.10 is using…
Justin Smith
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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 that's a separate problem. In order to try to get all…
A__A__0
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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 over GRE. RouterA is connected to internet via…
MABC
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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 local [local ip] remote [remote ip] ttl 255 Since the…
michael
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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 address 1.2.3.4 my local tunnel address Here the…
user158720
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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 ip add add 192.168.168.1/30 dev gre1 ip link set gre1…
wew
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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 for everything except, of course, running ISIS…
Jeff Learman
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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 On server A I setup the tunnel using: sudo…
user612795
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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 iptables -t nat -L POSTROUTING -v -n Chain…
sxc731
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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 remote REMOTE_IP udp_sport 5002 udp_dport 6002 ip l2tp…
Economist
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