I'm running an AWS Lightsail instance and I want to only be able to SSH to it from devices connected to my Tailscale network.
I installed Tailscale on the instance using their Ubuntu installation instructions. I have it running on my laptop and phone as well.
ifconfig tailscale0 to find the Tailscale IP for instance:
$ ifconfig tailscale0 tailscale0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1420 inet 100.122.168.55 netmask 255.192.0.0 destination 100.122.168.55 inet6 fe80::33a:342a:2733:186a prefixlen 64 scopeid 0x20<link> unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 500 (UNSPEC) RX packets 2147 bytes 95030 (95.0 KB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 990 bytes 66448 (66.4 KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
Then I ran
sudo vi /etc/ssh/sshd_config and added that address as the only
#Port 22 #AddressFamily any #ListenAddress 0.0.0.0 #ListenAddress :: ListenAddress 100.122.168.55
Then restarted SSH:
sudo service ssh restart
I can now SSH to Tailscale from my laptop, but only if I use the Tailscale IP address for the server (I thought it was broken at first because I was still SSHing to the internet public IP):
ssh firstname.lastname@example.org -i lightsail.pem
Bonus: point a real DNS subdomain at the Tailscale IP and you can
ssh email@example.com instead of remembering the IP address.
Handy debugging tip:
tail -f /var/log/auth.log shows recent sign-in attempts.
Thanks to @apenwarr for tips.
This conversation questions if the above recipe will work correctly when a server reboots. It seems it's possible that sshd might start up before the
tailscale0 network has been created, resulting in problems.
@bradfitz instead recommends adding the following line:
This will allow SSH access only from users within the Tailscale range of IPs. It shouldn't cause any problems during server startup.
This is complicated. See https://github.com/simonw/til/issues/7 for an explanation of a potential vulnerability in this pattern.
Created 2020-04-23T07:21:22-07:00, updated 2020-04-29T18:29:59-07:00 · History · Edit