[SCION] recvmmsg: connection refused

Benjamin Pereto benjamin at sandchaschte.ch
Wed Jul 7 16:35:17 CEST 2021


I'm currently trying to get the scionlab setup work on kubernetes. I'm doing this to better
understand how SCION works and improving my skills in kubernetes.

For the development, containers with docker-compose is already used, and I assume, it should also
work on kubernetes.

The setup is similar to https://docs.scionlab.org/content/config/setup_endhost.html and using the
scionlab packages for ubuntu with a ubuntu container image.

My Setup is behind a FW/NAT and a port-forwarding is configured. So, this **should** work.

A little overview of the topology:
SCION(17-ffaa:0:1107) -> 50000:router (NAT port-forward) -> k8s Service:50000/udp -> pod:50000/udp

Starting with the border-router, the startup seems as expected until:
Failed to read batch	{"err": "read udp recvmmsg: connection refused"}

TCPdump on my router shows:
* outgoing UDP packets from the border-router
* incoming ICMP unreachable message from the gateway of the attachement point 17-
ffaa:0:1107 as defined in the scionlab config/topology.json

16:20:52.043441 IP (tos 0xc0, ttl 38, id 8924, offset 0, flags [none], proto ICMP (1), length 148) > ICMP udp port 50195 unreachable, length 128
	IP (tos 0x0, ttl 37, id 58046, offset 0, flags [DF], proto UDP (17), length 120) > [udp sum ok] UDP, length 92

metrics also showing o router interface up:
curl -sfS   | grep router_interface_up
# HELP router_interface_up Either zero or one depending on whether the interface is up.
router_interface_up{interface="1",isd_as="17-ffaa:1:55",neighbor_isd_as="17-ffaa:0:1107"} 0

I'm aware, that this is not a supported setup, but eventually someone has a hint where I can debug?
What does the icmp unreachable from the scionlab gateway mean?
Is the dispatcher service needed for the border router?

Best regards,

[1] Logs of border-router: https://hastebin.com/dotovazoco.go

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