Hello, I have a rather complicated need to use a gre tunnel and I am having difficulty getting it working. The tunnel is between my home server and Oracle VM. Below is a picture of the topology with config.

Pings between the home server and Oracle VM over the gre tunnel do not seem to be going through as evidenced by tcpdump. I do notice however that the firewall has the correct state table showing that address translation. I am certain that both machines’ firewalls are not dropping packets because iptables is not showing anything dropped. I am at a loss here so I welcome any ideas.

    • @Parodper
      link
      2
      edit-2
      10 months ago

      I believe OP has made some mistakes when pasting the text


      [Diagram]
      Oracle VM: Linux
      External IP: 192.0.2.1
      Internal IP: 172.16.0.2
       |
       | GRE Tunnel
       v
      Home Server: Linux
      Internal IP: 172.16.0.2
       |
       |
       v
      Firewall: FreeBSD
      Internal IP: 172.16.0.1
      External IP: 192.0.2.2
      
      [Text]
      Home Linux Server GRE config:
      $ sudo ip tunnel add gre0 mode gre remote 172.16.0.2 local 192.0.2.1 ttl 255
      $ sudo ip link set gre0 up
      $ sudo ip addr add 10.100.10.1/24 dev gre0
      
      
      Home Linux Server GRE config:
      $ sudo ip tunnel add gre0 mode gre remote 192.0.2.2 local 192.0.2.1 ttl 255
      $ sudo ip link set gre0 up
      $ sudo ip addr add 10.100.10.1/24 dev gre0
      
      Firewall:
      nat on igb1 inet from ! (igb1) to any -> (igb1:0)
      nat on igb0 inet proto gre from 172.16.0.2 to any -> (igb1:0)
      rdr pass on igb1 inet proto gre from 141.148.84.178 to (igb1) -> 172.16.0.2
      
      • @tla@sopuli.xyz
        link
        fedilink
        110 months ago

        gre implies you want to run dynamic routing over the tunnel but no routing is configured? If you don’t need dynamic routing (why would you on a P2P tunnel?) but do want privacy then use IPsec or SSH instead?