Arch Linux

Lockheed

Member

Registered: 2010-03-16

Posts: 1,542

UDP traffic blocked on software bridge?

I am running OpenWrt 22.03.3 r20028-43d71ad93e in LXD as a router/edge device for my network.

My setup:

LXD OpenWRT with two interfaces:

-   physical eth0 passed through (WAN)
-   software bridge from host

Host:

  -  three physical NICs (eth1-eth3) bound in a software bridge (bridge with static IP)

Everything works fine except today I discovered that apparently, there is no ability to connect between two LAN devices on UDP ports.

I am trying to connect from computer A to computer B (both connected by cable to eth1 and eth3) using Moonlight, which requires following ports:

    TCP: 47984, 47989, 48010.
    UDP: 47998-48000, 48002, 48010.

If I forward those ports form WAN to B on LAN and try to connect from A using external network - everything works fine. However, when I try to connect from A to B when both are on LAN, A detects B, but cannot complete the handshake:

There are two changes since the last time it worked:

1 - upgraded from OpenWRT 19 to 22.03.3
2 - instead of passing each physical NIC into LXD and binding them into a bridge inside OpenWRT, I now bind them on host, and pass only the resulting bridge into OpenWRT's LXD. Thanks to that, I still have LAN when OpenWRT LXD is down, which is very helpful because I can still access the headless host and fix/upgrade/change LXD's config.

Any ideas?

Strike0

Member

From: Germany

Registered: 2011-09-05

Posts: 1,488

Re: UDP traffic blocked on software bridge?

Direct upgrade from OpenWrt 19 to 22 is not supported --> your config may be wrong.
22.03 is the first release with nftables as default --> check your custom rules.

Lockheed

Member

Registered: 2010-03-16

Posts: 1,542

Re: UDP traffic blocked on software bridge?

It was configured from scratch, not upgraded or restored.
Good point with nftables. What nftables rules should I look at?