mesh-net

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Changing a device's mesh address

Give a device of a private network a different 100.x address: what happens and what to watch out for.

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What happens

Every device of a private network gets a 100.x address when it joins. You can give it another one — for example, to keep a server at a memorable address or to bring back the address a device had before. The change is made on the network's server: its database gets the new address, the server restarts, and the device picks the address up by itself — nothing to do on the device.

Change the address

  1. Open the device's page. In Device details, next to Mesh address, press Change.
  2. New address is already filled with the nearest free address; keep it or type your own, like 100.64.0.10.
  3. Press Change address and confirm. In a few seconds the page shows the new address.

Which addresses are allowed

  • An IPv4 address inside the network's range, 100.64.0.0/10.
  • Not the first or the last address of the range.
  • Not reserved by Tailscale: 100.100.100.0/24 and 100.115.92.0/23.
  • Not used by another device of the network — the message names the device that has it.
  • One change at a time per network: if another address is being changed, try again in a minute.

A refused address changes nothing: the network isn't touched.

The pause and broken connections

Plan for a short pause

Network control pauses for about 5 seconds for all devices of the network: in that time no device can join, and settings don't reach the devices. Traffic between devices keeps flowing. TCP connections to the old address break — an SSH session or a database connection to the device has to be opened again.

The IPv6 address of the device stays the same.

What follows by itself, and what doesn't

  • Follows: visual access rules (they are built by device, not by address), published services that target the device, and the device's name in the network.
  • Doesn't follow: anything where you wrote the old address by hand — configs, scripts, bookmarks, a DNS record you pointed at 100.x, firewall rules on other devices. Update them.
  • The change is recorded in the network's notifications.

If anything fails during the change, the old address and the previous state are put back, and the message says what happened.

If the network uses custom HuJSON

A custom policy is yours: the dashboard doesn't rewrite it. Before the change the form reminds you of this, and after it the message says whether your policy mentions the old address. Replace it with the new one in the policy editor.

Where you can't change it

Addresses can be changed in private networks only. In the public network they are handed out by the shared server, and its devices have no device page with a Change button at all.