[Dnsmasq-discuss] Dnsmasq stops resolving addresses after return from suspend and wlan re-assoc

Toke Høiland-Jørgensen toke at toke.dk
Tue Dec 2 17:12:40 GMT 2014


Friendly bump on this? :)

-Toke

> I've been bothered for a while that my laptop (which runs a local
> dnsmasq instance for caching) stops resolving names after returning from
> suspend, and sometimes spontaneously as well. Restarting dnsmasq would
> always fix this.
>
> It finally started bothering me enough to debug it, and what I think
> happens is something like this:
>
> - Dnsmasq is configured to use the resolv.conf file maintained by
>   systemd-resolved, the nameserver manager component of
>   systemd-networkd. This file is updated whenever nameservers change
>   from DHCP or configuration.
>
> - Sometimes, it seems, systemd-resolved rewrites this file twice within
>   a fairly short time; once empty and again shortly after with the right
>   nameservers. Dnsmasq only picks up the first rewrite:
>
> Oct 19 19:44:50 alrua-x1 dnsmasq[30391]: reading /etc/dnsmasq-resolv.conf
> Oct 19 19:44:50 alrua-x1 dnsmasq[30391]: ignoring nameserver 127.0.0.1 - local interface
>
> But subsequently touching the file makes dnsmasq pick up on the change
> and name resolution works again:
>
> Oct 19 19:49:30 alrua-x1 sudo[2104]: alrua : TTY=pts/4 ; PWD=/home/alrua ; USER=root ; COMMAND=/usr/bin/touch /run/systemd/resolve/resolv.conf
> Oct 19 19:49:30 alrua-x1 sudo[2104]: pam_unix(sudo:session): session opened for user root by (uid=0)
> Oct 19 19:49:30 alrua-x1 sudo[2104]: pam_unix(sudo:session): session closed for user root
> Oct 19 19:49:33 alrua-x1 dnsmasq[30391]: reading /etc/dnsmasq-resolv.conf
> Oct 19 19:49:33 alrua-x1 dnsmasq[30391]: ignoring nameserver 127.0.0.1 - local interface
> Oct 19 19:49:33 alrua-x1 dnsmasq[30391]: using nameserver 10.61.32.1#53
> Oct 19 19:49:33 alrua-x1 dnsmasq[30391]: using nameserver 1.1.1.1#53
>
> Oddly enough, when first connecting to a network, there's a delay
> between the two writes of the resolv-file, which means things work:
>
> Oct 19 20:05:59 alrua-x1 systemd-networkd[960]: wlan0           : gained carrier
> Oct 19 20:05:59 alrua-x1 systemd-networkd[960]: wlan0           : DHCPv4 address 10.71.0.250/20 via 10.71.0.1
> Oct 19 20:05:59 alrua-x1 dnsmasq[22661]: reading /etc/dnsmasq-resolv.conf
> Oct 19 20:05:59 alrua-x1 dnsmasq[22661]: ignoring nameserver 127.0.0.1 - local interface
> Oct 19 20:06:03 alrua-x1 dnsmasq[22661]: reading /etc/dnsmasq-resolv.conf
> Oct 19 20:06:03 alrua-x1 dnsmasq[22661]: ignoring nameserver 127.0.0.1 - local interface
> Oct 19 20:06:03 alrua-x1 dnsmasq[22661]: using nameserver 10.61.32.1#53
> Oct 19 20:06:03 alrua-x1 dnsmasq[22661]: using nameserver 1.1.1.1#53
>
> Either way, fixing dnsmasq to always notice the updated files would be
> desirable. Not sure if the recently posted nanosecond resolution patch
> is the way to go about it, but consider this a motivation to do
> *something* :)
>
> -Toke



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