initial commit for docker dnsmasq and tailscale

Dockerfile

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+FROM ubuntu:22.04
+
+RUN apt-get update && apt-get install -y dnsmasq curl
+
+# Install Tailscale
+RUN curl -fsSL https://tailscale.com/install.sh | sh
+
+COPY dnsmasq.conf /etc/dnsmasq.conf
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]
+CMD ["dnsmasq", "--keep-in-foreground", "--log-facility=-"]

README.md

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 # local-dns-docker
 
+https://www.reddit.com/r/Tailscale/comments/1dql8a6/use_the_same_domain_name_on_home_network_and_on/
+
+What everybody has already said, but also use the tailnet IP of your DNS server as a global nameserver. I'll post my working steps:
+
+* Create a subnet router on your DNS host.
+
+1. On the DNS host you need to set --accept-dns=false
+2. advertise routes
+3. https://tailscale.com/kb/1019/subnets
+sudo tailscale up --accept-dns=false --advertise-routes=192.168.x.x/x
+
+* In tailscale Machines edit new host and allow new route(s)
+* In tailscale DNS, create a global namerserver:
+
+1. set it to the tailnet IP of your DNS server
+2. you can set split DNS here or you can just use your DNS for everything
+3. if u have android clients, check the slider to ignore local DNS
+
+* (optional) do the Linux enhancements mentioned on https://tailscale.com/kb/1019/subnets
+
+https://tailscale.com/kb/1019/subnets?tab=linux#connect-to-tailscale-as-a-subnet-router
+
+There is also a procedure to initially register the device with Tailscale server before this whole thing can work. Maybe I will document later. Not necessary as long as using the credentials in /DATA/AppData/tailscale/ so don't delete them.

dnsmasq.conf

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+# Don't use /etc/hosts or /etc/resolv.conf
+no-hosts
+no-resolv
+
+# Listen on all interfaces
+#interface=*
+interface=eth0
+interface=tailscale0
+
+# Resolve *.local to 192.168.1.16
+address=/.local/192.168.1.16
+
+# Forward other queries to 192.168.1.1
+server=192.168.1.1
+
+# Log queries
+log-queries
+log-facility=-
+
+# Don't use /etc/hosts
+no-hosts
+
+# Don't act as a DHCP server
+no-dhcp-interface=
+
+# Bind to all interfaces
+bind-interfaces

docker-compose.yml

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+version: '3'
+services:
+  dns-server:
+    container_name: dns-server
+    build: .
+    cap_add:
+      - NET_ADMIN
+      - SYS_MODULE
+    devices:
+      - /dev/net/tun:/dev/net/tun
+    volumes:
+      - /DATA/AppData/dns-docker:/var/lib/tailscale
+    network_mode: host
+    restart: unless-stopped

entrypoint.sh

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+#!/bin/bash
+tailscaled &
+tailscale up --accept-dns=false --advertise-routes=192.168.1.0/24
+exec "$@"