OpenVPN multicast?

  • Is multicast possible when setting up OpenVPN Site to site pre-shared key? Does it matter if the openvpn interface is tun or tap?

    If not "enabled" by default, how do i Enable multicast on the interfaces?

    Running latest version of pfsense 2.3.2

  • Rebel Alliance Developer Netgate

    Where are you trying to run multicast? Just between the firewalls on the OpenVPN interface, or from LAN-to-LAN?

    For traffic between the firewalls, it works fine with shared key depending on the context. Things like OSPF work without issue.

    If you are trying to get multicast from LAN to LAN, that is less likely to work. You'd have to run a proxy (e.g. Avahi) or bridge the LANs (yuck), but if you can provide some more information about what it is you're attempting to accomplish, there may be an alternate solution.

  • Thanks for the reply:-)

    What I would like to accomplish is to cluster two proxmox ( great hypervisor ) nodes that I have here at home and one node that is offsite.

    For clustering to work proxmox need  multicasting ( for what I have read? ) on the networks that are on the different sites.

    I have managed to setup an openvpn site to site with TAP interface but no traffic is passing, because the option to " Bridge DHCP" is greyed out? So is also Bridge interface? I have created and added the ovps interface, enabled it and bridged it with my LAN interface on the pfsense router in the datacenter, and ofcourse enabled the bridge also but still greyed out??

    Do you need more info??

    Thanks for the help again:-)


    Well, I was at this yesterday and tried again this morning with various settings but nothing.. I went back and configured an IPsec tunnel, multicast dont work on IPsec but there is a possibility to setup a GRE tunnel within the IPsec tunnel so I think I will try that instead..

  • I noticed that on certain hardware OpenVPN doesn't properly forward multicast unless you ckeck the box "Disable hardware checksum offload" in System / Advanced / Networking.

  • Has anyone been able to get this working?

    i'm trying to configure a 3 cluster configurations for my 3 proxmox noeds. 2 proxmox nodes are in the same physical network and i have no issues clustering them up.

    my issue is when i try to add the 3rd node which sits in a remote location, i get the "waiting for Quorum" time out  error, im assuming this is due to the multicast traffic not being passed through the S2S tunnel

    I've configured the ovpn server via TUN / UDP. i have access to the remote side, and vise versa. any suggestions ?

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