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# Stubby

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- Domain name resolution

Stubby is an application that acts as a local DNS Privacy stub resolver (using DNS-over-TLS). Stubby encrypts DNS queries sent from a client machine (desktop or laptop) to a DNS Privacy resolver, increasing end user privacy.

## Installation

Install the stubby package.

## Configuration

To configure stubby, perform the following steps:

### Select resolver

Upon installation, Stubby has some default resolvers. They can be found and edited in `/etc/stubby/stubby.yml`. You can use the defaults, uncomment one of prewritten resolvers or find another resolver from this list.

Example of a valid resolver configuration:

    /etc/stubby/stubby.yml

    upstream_recursive_servers:

    # The Cloudflare server
    - address_data: 1.1.1.1
        tls_port: 853
        tls_auth_name: "cloudflare-dns.com"

    # The Surfnet/Sinodun servers
     - address_data: 145.100.185.15
        tls_auth_name: "dnsovertls.sinodun.com"
        tls_pubkey_pinset:
          - digest: "sha256"
            value: 62lKu9HsDVbyiPenApnc4sfmSYTHOVfFgL3pyB+cBL4=

When you get warn log complaining wrong tls_pubkey_pinset, the tls_pubkey_pinset value may be wrong and the `value` of the `tls_pubkey_pinset` can be generated with:

    $ echo | openssl s_client -connect address_data:tls_port 2>/dev/null | openssl x509 -pubkey -noout | openssl pkey -pubin -outform der | openssl dgst -sha256 -binary | openssl enc -base64

Note: For further information on configuring Stubby see Configuring Stubby.

### Modify resolv.conf

After selecting a resolver, modify the resolv.conf file and replace the current set of resolver addresses with address for localhost:

    /etc/resolv.conf

    nameserver ::1
    nameserver 127.0.0.1
    options trust-ad

Other programs may overwrite this setting; see resolv.conf#Overwriting of /etc/resolv.conf for details.

### Start systemd service

Finally, start/enable the `stubby.service`.

## Tips and tricks

### Local DNS cache configuration

Stubby does not have a built-in DNS cache, therefore every single query is transmitted and resolved, which can slow down connections. Setting up a DNS cache requires installing and configuring a separate DNS cacher.

#### Change port

In order to forward to a local DNS cache, Stubby should listen on a port different from the default `53`, since the DNS cache itself needs to listen on `53` and query Stubby on a different port. Port number `53000` is used as an example in this section. In this example, the port number is larger than 1024 so stubby is not required to be run by root.

Edit the value of `listen_addresses` as follows:

    /etc/stubby/stubby.yml

    listen_addresses:
      - 127.0.0.1@53000
      -  0::1@53000

##### dnsmasq

Configure dnsmasq as a local DNS cache. The basic configuration to work with Stubby is the following:

    /etc/dnsmasq.conf

    no-resolv
    proxy-dnssec
    server=::1#53000
    server=127.0.0.1#53000
    listen-address=::1,127.0.0.1

Restart `dnsmasq.service` to apply the changes.

##### Other DNS cachers

For more DNS cachers, see DNSCrypt#Local DNS cache configuration. The configurations should be similar if not identical.

Category:

- Domain Name System