Route OVH IP block to Hetzner to be used by virtual machines?

H

harmonyp

Member
Nov 26, 2020
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Public IPv4 server 1 (OVH bare metal) : 141.94.199.xxx
Public IPv4 server 2 (Hetzner bare metal) : 5.9.105.xxx
IP block I want to use on server 2: 164.132.xxx.xxx/28 (OVH IP Block)

Can someone please assist me on how I can do this via GRE tunnel? Both have Proxmox installed.

Also what would the downsides be to this? (other than extra latency) I know there can be some issues with running a VPN for example due to MTU not being 1500
 
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I have tried the following which gets 164.132.xxx.1 pinging on the OVH node but not publicly.

Code: 
Public IPv4 (OVH) server 1: 141.94.176.xxx
Public IPv4 server 2 (Hetzner) : 5.9.105.xxx
IP block I want to use on server 2 (OVH IP Block): 164.132.xxx.0/28
Bridge interface server2: vmbr0

Run this on server 1:

ip tunnel add gre1 mode gre remote 5.9.105.xxx local 141.94.176.xxx ttl 255
ip link set gre1 up

Run this on server 2:

ip tunnel add gre1 mode gre remote 141.94.176.xxx local 5.9.105.xxx ttl 255
ip link set gre1 up

Then we need to create a route on server 1 that will route the IP traffic over the GRE tunnel

Run this on server 1:

ip route add 164.132.xxx.0/28 dev gre1

The next step is to route data from the GRE tunnel to the bridge and back.

Run this on server 2:

ip rule add from 164.132.xxx.0/28 table 666
ip route add default dev gre1 table 666
ip route add 164.132.xxx.0/28 dev vmbr0 table 666

Last thing to do is to add the a IP the to bridge. This is gonna be the gateway for you VM's!
Use the second IP of the range!

Run this on server 2:

ip addr add 164.132.xxx.1/28 dev vmbr0

OVH Node:

Code: 
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 02:00:00:c5:bc:6f brd ff:ff:ff:ff:ff:ff
    inet 141.94.176.xxx/32 brd 141.94.176.xxx scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::ff:fec5:bc6f/64 scope link
       valid_lft forever preferred_lft forever
3: gre0@NONE: <NOARP> mtu 1476 qdisc noop state DOWN group default qlen 1000
    link/gre 0.0.0.0 brd 0.0.0.0
4: gretap0@NONE: <BROADCAST,MULTICAST> mtu 1462 qdisc noop state DOWN group default qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
5: gre1@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN group default qlen 1000
    link/gre 141.94.176.xxx peer 5.9.105.xxx
    inet6 fe80::200:5efe:8d5e:b0a0/64 scope link
       valid_lft forever preferred_lft forever

Hetzner Node:

Code: 
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 50:eb:f6:22:f4:72 brd ff:ff:ff:ff:ff:ff
    inet 5.9.105.xxx/27 scope global enp7s0
       valid_lft forever preferred_lft forever
    inet6 2a01:4f8:162:4202::2/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::52eb:f6ff:fe22:f472/64 scope link
       valid_lft forever preferred_lft forever
3: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether a2:2a:09:2a:f3:36 brd ff:ff:ff:ff:ff:ff
    inet 164.132.xxx.1/32 scope global vmbr0
       valid_lft forever preferred_lft forever
    inet6 fe80::a02a:9ff:fe2a:f336/64 scope link
       valid_lft forever preferred_lft forever
4: vmbr1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether e2:b3:f0:04:70:50 brd ff:ff:ff:ff:ff:ff
5: gre0@NONE: <NOARP> mtu 1476 qdisc noop state DOWN group default qlen 1000
    link/gre 0.0.0.0 brd 0.0.0.0
6: gretap0@NONE: <BROADCAST,MULTICAST> mtu 1462 qdisc noop state DOWN group default qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
7: erspan0@NONE: <BROADCAST,MULTICAST> mtu 1450 qdisc noop state DOWN group default qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
8: gre1@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN group default qlen 1000
    link/gre 5.9.105.xxx peer 141.94.176.xxx
    inet6 fe80::200:5efe:509:69cc/64 scope link
       valid_lft forever preferred_lft forever
18: tap100i0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbr0 state UNKNOWN group default qlen 1000
    link/ether ae:50:31:a7:74:60 brd ff:ff:ff:ff:ff:ff

I tried creating a virtual machine with 164.132.xxx.2/28 and 164.132.xxx.1 as the GW but no luck either (does not ping from OVH or publicly)
 
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