Using cron to enable / disable pihole?

General Customizing Pi-hole
1

I've been using pihole to block facebook & twitter on my home wifi. I only want this block to operate between 10pm and 6am, when we should all be sleeping.

I've set up a crontab like so:

0 22 * * * PATH="$PATH:/usr/local/bin/" pihole enable
0 6 * * * PATH="$PATH:/usr/local/bin/" pihole disable

and pihole status reports enabled after 10pm as expected, so it would appear the cron job is working.

However, I don't actually see my network behaving as if pihole is enabled: browsers continue to access fb & twitter, and (for instance) dig facebook.com returns

facebook.com.		61	IN	A	157.240.1.35

e.g the DNS still resolves to the real server.

I do see things behaving as expected if I manually toggle Enabled / Disabled in the Pihole dashboard.

So, a question: should running pihole enable on the commandline and using the toggle on the dashboard theoretically do exactly the same thing? Why might it not do?

2

Are you using pi-hole as your sole DNS on your clients/router?

Enable/Disable should work as expected however if you use a secondary (non pi-hole DNS) your queries might go through that one ...

3

what's the output of nslookup facebook.com when blocking should be enabled?

4

I've just tried running pihole enable / disable manually at the CLI, and everything works as expected (browser and dig). So I guess it is a cron issue after all.

5

try setting up the PATH before the actual crontab:

PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin
0 22 * * * pihole enable
0 6 * * * pihole disable

6

Would not client DNS caching come into play here? Disabling pihole after a client has already resolved the domain, means it might not ask again for some time. It doesn't need to.

7

This strongly depends on your clients setup. Chrome, for example, has an internal DNS chace. Firefox, however, didn't had such a cache when I checked last time. It also depends on the operating system as many Linux systems come with a locally running caching DNS server such as dnsmasq which is doing nothing else than caching...

Which user is executing this cron rule? It should be root.

8

I agree. I am mostly pointing out that disabling/enabling pihole may not be completely effective if client caching is in play.

9

Can confirm that, on my Mac at least, Chrome and Firefox behave as @DL6ER says. This is why I was using dig to test, which seems to do fresh DNS queries.

Aha! I had been setting the cron rule using sudo crontab -e when logged in as pi on the Raspberry Pi running pihole; my assumption was that the sudo would mean that I was editing the crontab for root, but I now think I was wrong about that.

Editing /etc/crontab directly and specifying root as the user for the cron rules seems to have worked. Hoorah! Thanks, @DL6ER