My Little DoH Setup
"DoH"[1], this 3-letters acronym is a buzzword on the Internet in 2019! It has been implemented in Firefox, Microsoft announced that Windows will support it soon. They are pro & con about encrypting DNS requests in HTTPS but it's not the goal of this diary to restart the debate. In a previous diary, he explained how to prevent DoH to be used by Firefox[2] but, this time, I'll play on the other side and explain to you how to implement it in a way to keep control of your DNS traffic (read: how to keep an eye on DNS request performed by users and systems). For a while, I had the idea to test a DoH configuration but I had some requirements:
- It must be transparent for users
- DNS requests must be logged (who resolved which domain and when)
- Local DNS zones like 'lab.domain.tld' or 'iot.domain.tld' must be supported (resolved via a local bind instance)
- Users are protected via a PiHole[3] (against advertisements & malicious domains)
- Integration with 3rd party tools
This weekend, I decided to reconfigure my network. Here is my current setup:
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Endpoints (laptops, tablets, phones, visitors, etc) are using a PiHole instance (provided via DHCP) from their VLAN. Servers are using the normal Bind instance. PiHole forwards the allowed DNS requests to Bind. It is master and can resolve RFC1918 addresses from local zones (ex: *.lab.domain.tld). If the FQDN is unknown, it is forwarded to a local cloudflared[4] daemon via UDP/5353 that used DoH to resolve public names. To keep an eye on DNS requests, PiHole and Bind send their logs to my SIEM for further processing and reporting/alerting.
From a setup point of view, everything is running in Docker containers and, to increase my detection capabilities, my MISP instance is feeding PiHole and Bind with a daily export of malicious domains[5]. Let's see how it works in the coming days...
[1] https://en.wikipedia.org/wiki/DNS_over_HTTPS
[2] https://isc.sans.edu/forums/diary/Blocking+Firefox+DoH+with+Bind/25316
[3] https://pi-hole.net/
[4] https://github.com/cloudflare/cloudflared
[5] https://isc.sans.edu/forums/diary/DNS+Firewalling+with+MISP/24556
Xavier Mertens (@xme)
Senior ISC Handler - Freelance Cyber Security Consultant
PGP Key
Comments
Anonymous
Dec 3rd 2022
9 months ago
Anonymous
Dec 3rd 2022
9 months ago
<a hreaf="https://technolytical.com/">the social network</a> is described as follows because they respect your privacy and keep your data secure. The social networks are not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go.
<a hreaf="https://technolytical.com/">the social network</a> is not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go. The social networks only collect the minimum amount of information required for the service that they provide. Your personal information is kept private, and is never shared with other companies without your permission
Anonymous
Dec 26th 2022
9 months ago
Anonymous
Dec 26th 2022
9 months ago
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> nearest public toilet to me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
Anonymous
Dec 26th 2022
9 months ago
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> nearest public toilet to me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
Anonymous
Dec 26th 2022
9 months ago
Anonymous
Dec 26th 2022
9 months ago
https://defineprogramming.com/
Dec 26th 2022
9 months ago
distribute malware. Even if the URL listed on the ad shows a legitimate website, subsequent ad traffic can easily lead to a fake page. Different types of malware are distributed in this manner. I've seen IcedID (Bokbot), Gozi/ISFB, and various information stealers distributed through fake software websites that were provided through Google ad traffic. I submitted malicious files from this example to VirusTotal and found a low rate of detection, with some files not showing as malware at all. Additionally, domains associated with this infection frequently change. That might make it hard to detect.
https://clickercounter.org/
https://defineprogramming.com/
Dec 26th 2022
9 months ago
rthrth
Jan 2nd 2023
8 months ago