| 23 Jun 2026 |
 Nico | Well for forwarding, you need to setup something like a bridge, otherwise you will have just l2 connectivity to the other end of the tunnel | 16:44:44 |
 matthewcroughan | Ah okay so on one side of the tunnel I need a bridge, and on the other side I don't | 16:45:14 |
| Nico | I depends on what your goal is. If you setup a bridge you can use the other end of the tunnel for l2 protocols. If you have a dhcp server in the network you could try to run e.g. dhclient for debugging purpose | 16:46:47 |
| Nico | I'm not that familiar with the whole systemd-networkd configuration stuff. In ifstate it's pretty much straight forward.
Not sure why the hell this assigned the remote address to tun0... Kinda weird, if you ask me. Try to investigate using ip -d l tun0 | 16:51:26 |
| matthewcroughan | Oh I was just trying things to see if it changed anything | 16:53:32 |
| matthewcroughan | I was binding it to eth0 originally | 16:53:36 |
| matthewcroughan | tun0 is the ygg address and interface | 16:53:50 |
| Nico | Also when you say non ip traffic, do you mean common protocols like ethernet / llc or are you talking about proprietary protocols? | 16:53:57 |
| matthewcroughan | eth0 is where the actual non-ip stuff is happening | 16:54:00 |
| Nico | A tunnel (like gre) requires a local address and a remote address just to establish the tunnel itself.
If needed you can assign inner tunnel ips to the interface, but in your case, you may not want that in the end (it can be helpful for debugging) though.
Try to debug this using tcpdump, just to see if the tunnel has been established and your l2 traffic is being forwarded properly | 16:56:23 |
| matthewcroughan | yeah guess so, I just expected it to work :P | 17:04:20 |
| matthewcroughan | not used tcpdump before | 17:04:23 |
| matthewcroughan | Could it be MTU as well? | 17:05:09 |
| Nico | tcpdump protochain gre
| 17:05:13 |
| matthewcroughan | I've switched to using networking.greTunnels | 17:05:21 |
| matthewcroughan | Just to get to a more common setup | 17:05:29 |
| Nico | It depends, check tcpdump | 17:05:31 |
| Nico | Yea, wouldn't recommend that either 😂 | 17:05:50 |
| matthewcroughan | crap | 17:05:59 |
| matthewcroughan | I just need a good "working" config that is documented lol | 17:06:05 |
| Nico | Ifstate has an example :D | 17:06:31 |
| Nico | https://ifstate.net/2.4/examples/gretap/ | 17:06:33 |
| Nico | You can also just use the CLI instructions to create it | 17:07:09 |
| matthewcroughan | Nico: Do I need some ipv6 forwarding thing to exist and be set in sysctl? Nico | 17:14:30 |
 casey © | if you aren't forwarding ip, you don't need to enable forwarding ip. | 17:15:14 |
| matthewcroughan | My thoughts exactly, just wanted to confirm there's not some quirk | 17:15:49 |
| matthewcroughan | so I have both VMs open in shells now with no gre config, I'll try manually adding | 17:16:06 |
| Nico | 👍️ | 17:17:09 |
| matthewcroughan | [root@nixos:~]# ip -6 link add eogre type gretap local 200:fe12:89ec:86b6:ce32:9e0a:389:44d3 remote 200:25e6:e48d:963:3c5e:6466:87d4:a951 | 17:55:25 |
| matthewcroughan | this results in Error: inet address is expected rather than "200:fe12:89ec:86b6:ce32:9e0a:389:44d3". | 17:56:00 |
