feat: add support for SCTP#2007
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aauren merged 1 commit intocloudnativelabs:masterfrom Mar 10, 2026
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@damex I've just started testing this one, I may need a bit longer on this one depending on how the testing goes. |
aauren
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Hey @damex when I tried testing this I wasn't able to get an sctp client to talk to an sctp server via a service.
I did notice an error in the kube-router logs:
2026-03-09T02:05:37.779401362Z E0309 02:05:37.779285 19477 service_endpoints_sync.go:92] Error syncing ipvs svc iptables rules to permit traffic to service VIP's: could not save ipset for service firewall: ipset v7.24: Error in line 27: Syntax error: cannot parse 'sctp' as a protocol
This was performed on a host running: Ubuntu 24.04.4 LTS
I applied the following for an SCTP server:
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: sctp-server
spec:
replicas: 2
selector:
matchLabels:
app: sctp-server
template:
metadata:
labels:
app: sctp-server
spec:
containers:
- name: sctp-server
image: alpine
command: ["/bin/sh", "-c"]
args: ["apk add lksctp-tools && sctp_test -H 0.0.0.0 -P 36412 -l"]
ports:
- containerPort: 36412
protocol: SCTP
---
apiVersion: v1
kind: Service
metadata:
name: sctp-service
spec:
selector:
app: sctp-server
ports:
- port: 36412
targetPort: 36412
protocol: SCTP
type: ClusterIPAnd then for the client I ran:
kubectl run sctp-client --rm -it --image=alpine -- sh
# apk add lksctp-tools
# sctp_test -H 0.0.0.0 -P 0 -h <cluster_ip_from_above> -p 36412 -s
Maybe you could look into this a little deeper?
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looks like error from alpine side, right? http://git.musl-libc.org/cgit/musl/tree/src/network/proto.c looks like they don't use /etc/protocols and just hardcode those. i think either patch musl (patch upstream)... or... would it be acceptable to do protocol by name -> numeric value mapping here? on a side note - do you think we could add some 'test' so this type of error could be caught next time? simple check with alpine and here is the ubuntu |
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Interesting! Yeah I can confirm that I was using the official kube-router which is based on Alpine and seems to confirm what you found. I would say using the integer mapping should be good enough to make it work everywhere for now and maybe get around the musl quirks. I can't think of a unit test that would test for this and this repo doesn't really do integration tests for now (although it has been something that @catherinetcai has been thinking about). |
includes workaround for musl hardcoded protocol table that is missing SCTP support by using protocol name to numeric value mapping in ipset entries closes: cloudnativelabs#1019 Signed-off-by: Roman Kuzmitskii <roman@damex.org>
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@aauren added exception/workaround for SCTP ipset handling. well, i can also try to send patch to musl to include 'sctp support' so we could drop this workaround :) |
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This LGTM thanks for the contribution and for the updates!
I'm sure that musl would appreciate the protocol contribution if you're interested in making it! It seems like a neat project to be a contributor to. 🙂
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