tpwo / dns-update-wsl2

Automatically update WSL2 resolv.conf.

dns-update-wsl2

Perl script that automatically updates WSL2 resolv.conf file based on DNS servers extracted from ipconfig.exe /all output. Cloudflare 1.1.1.1 DNS is always added as the last server.

The script might be useful when your DNS servers often change from any reason, and you cannot count on resolv.conf being auto-generated by WSL2 (because it can be wrong when using corporate network etc.).

E.g. you might be working from home via the VPN, and then from the office with different DNS servers in these two situations.

Before using the script, you have to turn off the auto-generation of resolv.conf file. It can be done by placing the following in etc/wsl.conf in your WSL distro:

[network]
generateResolvConf = false

See more information about that in Microsoft Docs.

Limitations

Script is able to only detect IPv4 DNS servers.

How to use?

Obtain dns-update-wsl2 script in any preferred way, and just run it. The generated file will be presented to you with the choice to abort or proceed. With choosing the latter option, you will be prompted for your password, because sudo is required to move the file to /etc.

You might want to place the script on your PATH to have an easier access to it.

Example output:

$ ./dns-update-wsl2
Temporary resolv.conf generated:

# Auto-generated from ipconfig.exe
# on Mon Apr 11 20:13:13 2022
nameserver 123.456.789.37
nameserver 9.8.7.6
nameserver 1.1.1.1

Update 'etc/resolv.conf'? (y/N): y
Using sudo to update '/etc/resolv.conf'...
Successfully updated '/etc/resolv.conf'!

sudo

Running the script as root or with sudo will fail because for some reason ipconfig.exe doesn't return any output in such case. This script prompts for sudo later on its own, and thus should be called with the standard user privileges.

Running the script with root privileges will cause it to exit at the very beginning.

License

Copyright 2022 Tomasz Wojdat

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.