arbal / tailscale-hostmap

Automatically map Tailscale hosts to DNS names locally

tailscale-hostmap

Automatically map Tailscale hosts to DNS names in /etc/hosts. No more copy-pasting Tailscale IP addresses!

This script modifies your system's hosts file to include all your Tailscale machines, allowing you to e.g. ssh into them as if they were on your local network (with optional domain suffix).

Running it again will update the existing configuration. Designed to take 10 seconds to setup.

Q: Isn't this similar to Tailscale's own Magic DNS?
A: Yes, but:

• has some extra flexibility, as you can also add DNS entries for shared machines, and you can specify a DNS domain to use (e.g. a host raspberrypi can become raspberrypi.ts)
• Is faster to resolve - Magic DNS is slow in my experience
• Can be enabled for just one or two machines, instead of your entire network.
• Doesn't take over the entire DNS resolver (so allows for arbitrary resolution for non-tailscale hostnames)

10-second Setup (Linux)

Run the following two lines in a shell:

# Important that the downloaded file is only writeable by root, or this could allow for privilege escalation
sudo wget https://raw.githubusercontent.com/mxbi/tailscale-hostmap/main/tailscale-hostmap.py
echo "*/5 * * * * root /usr/bin/python3 `pwd`/tailscale-hostmap.py --domain ts -s" | sudo tee /etc/cron.d/tailscale-hostmap

The configuration above includes shared machines, and adds a .ts domain to hostnames. So if a host on your network is called lynx, you'll be able to ssh lynx.ts. The configuration will be updated every 5 minutes.

Usage/Installation

To update entries e.g. every 5 minutes, download tailscale-hostmap.py and add it as a cronjob, for example by creating a file in /etc/cron.d and adding a new line:

*/5 * * * * /usr/bin/python3 PATH_TO_FILE/tailscale-hostmap.py --domain ts -s

You can use a crontab generator to help with this!

There are some optional flags:

usage: tailscale-hostmap.py [-h] [--domain DOMAIN] [-s] [--ts-binary TS_BINARY] [-ip4] [-ip6]
                            [--hosts-file HOSTS_FILE]

optional arguments:
  -h, --help            show this help message and exit
  --domain DOMAIN       The domain to append to the hostname. For example, `pi` becomes `pi.ts` when
                        domain=`ts`. Defaults to no domain
  -s, --include-shared  Add this flag to also include shared machines in DNS
  --ts-binary TS_BINARY
                        The location of the tailscale binary to call. Defaults to /usr/bin/tailscale
  -ip4, --ip4           Add this flag to limit processing to ip4 addresses
  -ip6, --ip6           Add this flag to limit processing to ip6 addresses
  --hosts-file HOSTS_FILE
                        The location of the hosts file to update. Defaults to /etc/hosts

Important notes:

• The script needs to run with sudo as /etc/hosts is a privileged file. No requirements needed except Python3.7.
• The downloaded file must only be writeable by root. If the file is writeable by other users, this could allow for privilege escalation.
• Any hostname with spaces in it has the spaces replaced by dashes.