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Routing /26 subnet over GRE tunnel not working on windows guests.
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Routing /26 subnet over GRE tunnel not working on windows guests.

jordynegen11jordynegen11 Member
edited April 2019 in Help

Hi,

Me and @malik managed to route a /26 subnet from a OVH server to a server in another DC via a GRE tunnel.

All routing is working and we created a network in libvirt called ovh:

The problem is: This is working perfectly on a Linux guest (we have internet via the /26 subnet) but on a Windows guest we can't get a connection. It is getting an IP from the DHCP but after that, no connection at all. We also can't ping the gateway (151.x.x.129) from the Windows or linux guest.

interface settings of the guests are the same.

Does anyone know why? Is this a bug in libvirt or kvm?

Comments

  • update: For a reason sometime the connection of the windows VM is working for 5 minutes and then its dead again.

  • Are you using solusvm ?

  • Tr33nTr33n Member
    edited April 2019

    Could be an ARP issue. I would try it with the rtl8139 / e1000 network driver and if it works, update the virtio driver inside the guest.

    tcpdump will be your friend for troubleshooting this.

  • Upgraded to kernel from 3.1 to 5.0 on centos 7.6. and the connection is way more stable now. Tomorrow I will test further.

  • @belemenon said:
    Are you using solusvm ?

    Custom panel using libvirt

  • jordynegen11jordynegen11 Member
    edited April 2019

    So I can confirm now that the problem has been resolved. The problem was the outdated linux kernel on Centos 7.6 (3.1). I updated the kernel on both servers to 5.0 and now it's working perfectly!

    Thx to @malik for the tip

  • The problem did return but not as much as earlier. I noticed when I flushed the ARP cache every second, there are no problems anymore. Someone knows why?

  • Tr33nTr33n Member

    Yes

  • So it turns out the libvirt bridged interface has a little bug in it. I created a bridged interface without libvirt, changed some routes and BOOM. working perfect now.

  • emreemre Member, LIR

    jordynegen11 said: So it turns out the libvirt bridged interface has a little bug in it. I created a bridged interface without libvirt, changed some routes and BOOM. working perfect now.

    waiting for your promised "how to" document here.

  • jordynegen11jordynegen11 Member
    edited April 2019

    @emre said:

    jordynegen11 said: So it turns out the libvirt bridged interface has a little bug in it. I created a bridged interface without libvirt, changed some routes and BOOM. working perfect now.

    waiting for your promised "how to" document here.

    No worry my friend

    https://www.lowendtalk.com/discussion/156850/howto-tunnel-ddos-protected-ovh-ip-to-vms-in-other-datacenter#latest

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