[Starlink] starlink and VPN

[David Lang]

Gert Doering wrote:

> Hi,
>
> On Mon, Jan 20, 2025 at 11:25:04PM -0800, David Lang via Starlink wrote:
>> the logs on the client are reporting link local: (not bound) when trying
>> UDP, when I try TCP (and clamp the mtu low) I can connect from the starlink
>> side (st least sometimes) but cannot get the routing the other way to work
>
> If the VPN comes up (both sides declare TLS handshake success, you see
> the PUSH_REPLY messages on both sides), with TCP, it "should just work"
> - if not, it's not a starlink issue but something in the OpenVPN setup,
> or just a plain "ipv4_forward=1" missing on the server side...

I am expecting that it is something in my configs, but I think there is some 
interaction with Starlink as it did connect when I used my phone hotspot for my 
WAN (I didn't try connecting back)

> Feel free to unicast me your OpenVPN logs (verb 3) if needed.

I will probably take you up on that. I'm going to do a little more testing 
first.

> With UDP, "it should also work just fine", but MTU might interfere - and
> of course UDP rate limiting.  Try "openvpn --max-packet-size 1000" or
> even lower, if it's really MTU related (tcpdump on both ends on the outside
> interface should show if packets are getting lost).

that's more or less where I ended up that finally got it working in one 
direction. I was hoping that someone could say what MTU I needed to set it to 
rather than having to manually test. :-)

It may be that I missed a step in the client router and the tun interface is not 
in the correct firewalling to allow connections back

David Lang

> Gert Doering
>        -- openvpn upstream
>