When browsing internet, it often happens that a name couldn’t be resolved, and reloading the page works.
The /var/log/resolver
file looks like this:
Mar 18 17:26:02 turris kresd[20765]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:29:28 turris kresd[21232]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:31:08 turris kresd[21539]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:40:36 turris kresd[22251]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:40:45 turris kresd[22500]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:46:08 turris kresd[23054]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:46:52 turris kresd[23334]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:47:02 turris kresd[23584]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:47:36 turris kresd[23850]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:47:44 turris kresd[24099]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:49:03 turris kresd[24495]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
Mar 18 17:49:12 turris kresd[24745]: [system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
which suggests that the kresd
daemon is restarted periodically. I enabled verbose debug ( /etc/resolver/resolver-debug.sh start
), and can see that the failed requests don’t make it to the log.
Because of that, I suspect that that the failed DNS requests happen during the kresd
restart cycle.
From the other threads, it seems that the file-descriptor limit is unlikely to cause problems, and likely is not related to the frequent service restarts. However, the frequent restarts itself may be a problem.
Could you hint me what next steps I can take to debug the issue?
I tried to run kresd from the command line rather than as a deamon, to see whether it crashes with some SIGSEGV or something else, but it didn’t seem to work:
root@turris:~# /etc/init.d/resolver stop
Called /etc/init.d/kresd stop
remove dhcp script
root@turris:~# /usr/sbin/kresd --noninteractive -c /tmp/kresd.config /tmp/kresd
[system] warning: hard limit for number of file-descriptors is only 4096 but recommended value is 524288
↑↑ The kresd did run, but actually none of DNS requests in my local network were answered.