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freifunk-gluon / gluon

a modular framework for creating OpenWrt-based firmwares for wireless mesh nodes
https://gluon.readthedocs.io
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fix issue that causes dnsmasq log spam #3262

Closed Djfe closed 3 months ago

Djfe commented 5 months ago

dnsmasq started spamming my logs a couple months back

Wed May 15 01:34:07 2024 daemon.info dnsmasq[1]: reading /tmp/resolv.conf.d/resolv.conf.auto
Wed May 15 01:34:07 2024 daemon.info dnsmasq[1]: using nameserver 2a03:2260:3006::53#53
Wed May 15 01:34:07 2024 daemon.info dnsmasq[1]: using only locally-known addresses for lan

this is mostly just a bit of an annoyance because it makes the logs harder to read. atleast Gluon v2023.2 is affected, v2023.1 might be affected as well (I think I remember seeing it there as well).

I just wanted to report this here so we don't forget about it. Also the spam could be a symptom of an actual issue (dnsmasq restarting every 5minutes)

site: https://github.com/ffac/site/tree/v2023.2.2-1 gluon tag: 00160f5bd48261156cef1c4e626e1b8dffba2650

maurerle commented 3 months ago

I heard from @grische that this has been seen on ffdon before their migration to ffmuc: https://github.com/ffdon/site-ffdon/blob/master/site.conf

As most other communities do not experience this, while I heard that FFAC also experienced this in the old 2019.x firmware (as far as I heard), I looked into common configuration of the two: https://github.com/ffac/site/blob/v2023.2.x/site.conf

Both firmwares do not have a dns section baked in the config.

Most other communities and the new FFMUC config do have this: https://github.com/freifunkMUC/site-ffm/blob/stable/domains/ffdon_nordwest.conf

one can see, that dnsmasq restart as it rewrites the config: ls -l --full-time /tmp/resolv.conf.d/resolv.conf.auto

Adding: uci add_list dhcp.@dnsmasq[0].server='2a03:2260:3006::53' && uci commit dhcp did not fix the restart. (though it seemed to occur less often..)

Maybe building a firmware with dns settings baked in helps. It might be that a configuration as "gluon does not know about a dns server as it gets one pushed from the kea from the supernode anyway" does lead to these restarts. I do not know what it could be other than that.

neocturne commented 3 months ago

Discussion of the issue on IRC has revealed that it was caused by two supernode radvds announcing different lists of DNS Search Domains, resulting in frequent rewrites of resolve.conf.auto.