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:

```bash

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:

bash */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.

Issues

Tried to run the script, but get error

opened on 2022-11-08 08:28:05 by metasikander

when i run the script it i get an error: bash ~]$ sudo /usr/bin/python /usr/bin/tailscale-hostmap.py Traceback (most recent call last): File "/usr/bin/tailscale-hostmap.py", line 210, in <module> sys.exit(main()) File "/usr/bin/tailscale-hostmap.py", line 198, in main hosts_lines = update_hosts(format_hosts_lines(tailscale_peers())) File "/usr/bin/tailscale-hostmap.py", line 110, in format_hosts_lines if len(valid_peers(peers)): TypeError: object of type 'generator' has no len() do you have an idea why this might be happening?

OS: Fedora 36 Pyton: Python 3.10.7

Better detection of shared devices

opened on 2021-11-01 20:23:37 by mxbi

This issue only applies to domain Tailnets.

If tailscale-hostmap is running on device A, and device B connects to A, then B will appear in A's DNS entries even if B cannot access A (for example, through ACLs).

The current code detects these machines as shared machines. It may be better to figure out which machines are actually reachable and only setup DNS entries for those machines.