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@foros.fediverso.gal
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    1 year 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
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      1 year 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?