HOWTO: Using Pi-hole DNS to block ads. The struggle continues…
This article is a work in progress. Updated: 2020-05-02. This is turning into a bit of a catch-up on the state of DNS for me.
Day 03 and 04 of #100DaysToOffload.
Intro
The war against ads continues. https://pi-hole.net/ looks like a reasonable, good, new?, open source entry in the war against ads. Get ‘yer source/install for linux at https://github.com/pi-hole/pi-hole
Per Paul Vixie
not even non-technical users need a “public DNS” to shield themselves from a lot of known-evil internet sites. check out @The_Pi_Hole or have your 12yo child or cousin install it.
..but I always make things harder.
Figure 1: pi-hole console after a few hours on my system
What
- It’s a local DNS server to block adds.
Why
- Blocking ads is a moral good.
- I’ve not done home network hacking for a while.
- I’m moving into a bit of a more “don’t track me” frame of mind.
When
- Now, because I’m home more during corona-virus.
How
- Set up local server.
- First on a Linux laptop that (usually) does not go off the net.
- Then maybe on an old pogoplug or laptop.
Install It
Here’s what I did to instlal
- [ ] basic install
- On a Linux server, the basic install is
simple:
sudo bash basic-install.sh - [ ] Static IP
- But you will want a Linux box with a static IP address. This may involve, e.g., convincing your wireless router to hand out a the same static IP to a static IP
- [ ] Tell other systems to use this IP for DNS
- Again, probably configuring your wireless router to specify your local IP as the DNS server for DNS assignments via DHCP assignments. You could also do this by configuring the individual devices to use it.
- [ ] Remember your admin password
- Make note of the admin password during install
- [ ] hit the local admin web server
- Its a very nice. It will be at a something like http://192.168.86.230/admin/index.php.
Test It
- [ ] Look something up by hand
- Use dig(1) or host(1). Note
the
SERVERin the response below that shows where the answer came from. If it’s your IPS’s DNS or Google, try again (something’s not configured right). In my case 127.1 is right.
$ dig www.uu.net
; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> www.uu.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54721
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;www.uu.net. IN A
;; ANSWER SECTION:
www.uu.net. 299 IN CNAME global.mci.com.
global.mci.com. 959 IN CNAME wac.C449.edgecastcdn.net.
wac.C449.edgecastcdn.net. 3599 IN CNAME gp1.wac.v2cdn.net.
gp1.wac.v2cdn.net. 3599 IN A 152.195.32.39
;; Query time: 59 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri May 01 19:16:11 EDT 2020
;; MSG SIZE rcvd: 146
-
Check the query logs via the UI to make sure your target domain showed. Be aware of caching. It may only show up the first time you query.
-
Find your favorite 90s-era web site, go hit it, and watch the counters
- http://computershopper.com
- http://www.yahoo.com
- http://www.compuserve.com
- http://www.aol.com
- http://sears.com (get it while it lasts)
-
If the counters go crazy and you don’t see the expected plethora of ads, you win. If not dig deeper.
-
If you are already using ad-blockers or browsers such as Brave that block ads, you may have to test with something else (Firefox, Chrome, etc.)
-
Browser and other apps are getting cagey about using not using the system DNS, using DOH, and otherwise not acting like you expect them too. Editing
/etc/resolv.confis not the whole game anymore.
Tools you may want to use/learn/install
- dig
- for making/testing queries by hand
- Wireshark
- Use Wireshark to see what’s going on on the wire, who you’re talking to, etc.
The things you learn
-
pi-hole can apparently function as a DHCP server itself.
-
You can choose your upstream DNS servers from a list with options for IPv4, IPv6, DNSSEC/no DNSSEC, filtered/unfiltered.
-
Quad9 is one of the choices. It looks to be really useful for adding malware blocking to your domain. See https://www.quad9.net/faq/ for a useful bit of education.
-
The logs are at
/var/log/pihole.log -
Possibly use Marcus Ranums’s principal of “Artificial Ignorance” to grep out the known and see what’s left:
$ cat pihole.log.1 | egrep -v microsoft.com\|google\|amazon\|in-addr\|linkedin\|dropbox\|facebook\|messenger\|ubuntu\|github\|brave\|basicattention\|yahoo\|disqus\|twitter\|akamai\ | sed 's/.*: //' | sort | uniq -c | sort -rn | head 334 reply min-api.cryptocompare.com is <CNAME> 334 reply ccc-api.cloudapp.net is 40.115.22.134 334 query[A] min-api.cryptocompare.com from 127.0.0.1 238 forwarded min-api.cryptocompare.com to 8.8.4.4 143 cached min-api.cryptocompare.com is <CNAME> 101 query[A] no-thanks.invalid.lan from 127.0.0.1 101 query[A] no-thanks.invalid from 127.0.0.1 101 forwarded min-api.cryptocompare.com to 8.8.8.8 100 reply hfq2h9152m63.statuspage.io is <CNAME> 100 query[A] rpt.cedexis.com from 127.0.0.1$ cat pihole.log.1 | egrep -v microsoft.com\|google\|amazon\|in-addr\|linkedin\|dropbox\|facebook\|messenger\|ubuntu\|github\|brave\|basicattention\|yahoo\|disqus\|twitter\|akamai\|compuserve\|aol | sed 's/.*: //' | sort | uniq -c | sort -rn | tail -20 1 cached imap.gmail.com is 2607:f8b0:400d:c0f::6d 1 cached imap.gmail.com is 2607:f8b0:400d:c07::6d 1 cached imap.gmail.com is 2607:f8b0:400d:c00::6d 1 cached imap.gmail.com is 2607:f8b0:4004:c08::6d 1 cached imap.gmail.com is 2607:f8b0:4004:c08::6c 1 cached imap.gmail.com is 172.253.63.109 1 cached imap.gmail.com is 172.253.63.108 1 cached hosts-file.net is 3.234.198.254 1 cached encrypted-tbn0.gstatic.com is 172.217.13.78 1 cached dig is NXDOMAIN 1 cached content-signature-2.cdn.mozilla.net is <CNAME> 1 cached beacons-handoff.gcp.gvt2.com is 172.217.15.99 1 cached beacons.gvt2.com is 172.217.13.227 1 cached beacons.gcp.gvt2.com is <CNAME> 1 cached beacons4.gvt2.com is 216.239.32.116 1 cached beacons2.gvt2.com is 216.239.38.117 1 cached beacons2.gvt2.com is 216.239.36.117 1 cached beacons2.gvt2.com is 216.239.34.117 1 cached beacons2.gvt2.com is 216.239.32.117 1 cached article.smartasset.com is <CNAME>What is this stuff?
Tune it
I’m not sure all the devices in the house are using the P-hole proxy. If they are, then they are showing up as the single device _gateway. I need to understand this and figure out if I can get other devices pulling wireless addresses via DHCP from the WAP to use the Pi-hole DNS directly. Stay tuned.