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

learn more… | top users | synonyms

4
votes
1answer
10k views

PPTP connection fails with errors 800/806

I've got a client (Server 2008 R2) that won't connect to our production environment PPTP VPN server (Server 2003, running RRAS). The server is behind a firewall that has TCP1723 open as well as GRE. ...
2
votes
1answer
591 views

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 ...
2
votes
1answer
3k views

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 ...
1
vote
1answer
675 views

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 ...
1
vote
1answer
848 views

How to enable debug logging for GRE?

How to enable debug logging for module ip_gre on linux 2.6?
0
votes
1answer
10 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 ...
0
votes
1answer
50 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 ...
0
votes
1answer
111 views

Load balancing between two (or more) GRE tunnels

I have a hosted service (think zScalerā„¢) 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 ...
0
votes
1answer
90 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 ...
0
votes
1answer
130 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 ...
0
votes
1answer
441 views

TLS-intolerant sites suddenly not working

About 2 weeks ago users started reporting that they were unable to access two https-only sites. When I inspected these sites I found they were completely intolerant to TLS. In order to connect, SSL3 ...
0
votes
1answer
516 views

GRE Tunnel in CentOS

How to create a GRE Tunnel in CentOS pointing all connections to server A for the server B? I have a public server with DDoS protection and need to use this as a firewall to filter acess to the other ...
0
votes
1answer
683 views

How to troubleshoot GRE tunnel issues?

I commonly run into issues where a GRE tunnel (CentOS server to server, not router based) works and pings fine from both ends but the IP / Range being tunneled does not function. This almost always ...
0
votes
1answer
2k views

Gre Tunnel Cisco Linux traffic forwarding

I setup a gre tunnel a cisco router and a Linux machine, the tunnel interface in the Linux box named pic. Well i have to forward traffic coming from cisco through the Linux box. the rules i've set in ...
1
vote
0answers
33 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 ...
1
vote
0answers
93 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 ...
1
vote
0answers
32 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. ...
1
vote
0answers
43 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 ...
1
vote
0answers
41 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 ...
1
vote
0answers
365 views

Using my IPs on OVH server via GRE

I can't route my IPs into a OVH server, can you help me to find the problem? Mikrotik GRE IP: 192.168.55.10 OVH Server GRE IP: 192.168.55.20 GRE iface name: ali1_fr1-ovz1 IP to route from Mikrotik to ...
1
vote
0answers
1k views

OpenNHRP configuration without IPsec

I'm attempting to use OpenNHRP on a linux box to connect with a Cisco Router. I want to allow GRE tunnels from the linux box to the Cisco router dynamically, but I'm not implementing DMVPN on the ...
1
vote
0answers
445 views

GRE debug: “adding 0 encap bytes”?

What this debug message actually means? Shouldn't encapsulation add 24 extra bytes or not? For what reason encapsulation is not adding bytes to original packet in this debug message? Dec 28 ...
0
votes
0answers
25 views

multi gre tunnels to one IP

I have an issue with GRE tunnels after connecting multi-GRE tunnels with different IP's to the server, using this tutorial: http://wiki.buyvm.net/doku.php/gre_tunnel every GRE tunnel has interface ...
0
votes
0answers
21 views

DNS using GRE work 50%

l'm in a big issue here to make it work I'm already at least about 60% done, but it is difficult and I would like to count on the help guys here who may have already done this type of configuration. ...
0
votes
0answers
111 views

TCP Out-of-order packets over GRE causing disconnect

I'm experiencing an issue with a small percentage of TCP connections over a GRE tunnel between two servers. The topology is basically Internet <-> GRE Tunnel <-> Backend The GRE tunnel and the ...
0
votes
0answers
317 views

Strongswan IPsec: routing arbitrary subnets over /32 IPsec endpoints

I have a basic setup between two sites A (FreeBSD, 10.0.0.1/24 nat'd to 1.1.1.1), B (Linux, 2.2.2.2), with only A behind NAT. I've only been able to get it working in tunnel mode. Here's my ...
0
votes
0answers
71 views

Openbsd set connect on PPTP server behind packet filter

I have firewall on OpenBSD use Packet Filter and behind him MS Windows server with PPTP server. I need allow connect this PPTP server from internet. I set in OpenBSD: net.inet.gre.allow=1 ...
0
votes
0answers
218 views

AWS VPC: Windows server 2012 R2 GRE tunneling to Linux based Peer VyOS

I am asking this question after having spent some time googling and trying to work out some issues which I have with a Windows GRE tunnel in our 2nd environment (amazon AWS VPC) to a router in our ...
0
votes
0answers
46 views

Add FQDN name in gre tunnel in Linux

Since aruba, cisco, etc all support add FQDN as gre tunnel's endpoint, can I do the same thing in linux via iproute2 or something else? Now, when I type a FQDN at ip tunnel, it just says that it's ...
0
votes
0answers
73 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. ...
0
votes
0answers
125 views

Listening “through” GRE Tunnel

Currently I'm looking to learn about using GRE Tunnels and I have the following scheme: Server1 (200.1.2.3) ----> Server2 (190.1.2.3) Both servers have public IPs Then I've setup a GRE Tunnel with ...
0
votes
0answers
325 views

Using public interfaces on a server connected through a GRE tunnel

I'm pretty new to networking so please forgive any terminology mistakes. I have 2 servers connected with a GRE tunnel. Server1 (10.0.0.1) ----> Server2 (10.0.0.2) I want to be able to bind to the ...