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blocky/docs/configuration.md

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Configuration

This chapter describes all configuration options in config.yaml. You can download a reference file with all configuration properties as JSON.

??? example "reference configuration file"

```yaml
--8<-- "docs/config.yml"
```

Basic configuration

Parameter Type Mandatory Default value Description
port [IP]:port no 53 Port and optional bind ip address to serve DNS endpoint (TCP and UDP). If you wish to specify a specific IP, you can do so such as 192.168.0.1:53. Example: 53, :53, 127.0.0.1:53
httpPort int (1 - 65535) no HTTP listener port and optional bind ip address . If > 0, will be used for prometheus metrics, pprof, REST API, DoH ...If you wish to specify a specific IP, you can do so such as 192.168.0.1:4000. Example: 4000, :4000, 127.0.0.1:4000
httpsPort int (1 - 65535) no HTTPS listener port and optional bind ip address . If > 0, will be used for prometheus metrics, pprof, REST API, DoH... If you wish to specify a specific IP, you can do so such as 192.168.0.1:443
httpsCertFile path yes, if httpsPort > 0 path to cert and key file for SSL encryption
httpsKeyFile path yes, if httpsPort > 0 path to cert and key file for SSL encryption
bootstrapDns IP:port no use this DNS server to resolve blacklist urls and upstream DNS servers. Useful if no DNS resolver is configured and blocky needs to resolve a host name. NOTE: Works only on Linux/*Nix OS due to golang limitations under windows.
disableIPv6 bool no false Drop all AAAA query if set to true
logLevel enum (debug, info, warn, error) no info Log level
logFormat enum (text, json) no text Log format (text or json).
logTimestamp bool no true Log time stamps (true or false).
logPrivacy bool no false Obfuscate log output (replace all alphanumeric characters with *) for user sensitive data like request domains or responses to increase privacy.

!!! example

```yaml
port: 53
httpPort: 4000
httpsPort: 443
logLevel: info
```

Upstream configuration

To resolve a DNS query, blocky needs external public or private DNS resolvers. Blocky supports DNS resolvers with following network protocols (net part of the resolver URL):

  • tcp+udp (UDP and TCP, dependent on query type)
  • https (aka DoH)
  • tcp-tls (aka DoT)

!!! hint

You can (and should!) configure multiple DNS resolvers. Blocky picks 2 random resolvers from the list for each query and
returns the answer from the fastest one. This improves your network speed and increases your privacy - your DNS traffic
will be distributed over multiple providers.

Each resolver must be defined as a string in following format: [net:]host:[port][/path].

| Parameter | Type | Mandatory | Value | Default value | | --------- | -------------------------------- | -------------------------------------------------------- | ------------------------------------------------- | | net | enum (tcp+udp, tcp-tls or https) | no | network protocol | tcp+udp | | host | IP or hostname | yes | full qualified domain name or ip address | | | port | int (1 - 65535) | no | number < 65535 | 53 for udp/tcp, 853 for tcp-tls and 443 for https |

Blocky needs at least the configuration of the default group. This group will be used as a fallback, if no client specific resolver configuration is available.

You can use the client name (see Client name lookup), client's IP address or a client subnet as CIDR notation.

!!! tip

You can use `*` as wildcard for the sequence of any character or `[0-9]` as number range

!!! example

```yaml
upstream:
  default:
    - 46.182.19.48
    - 80.241.218.68
    - tcp-tls:fdns1.dismail.de:853
    - https://dns.digitale-gesellschaft.ch/dns-query
  laptop*:
    - 123.123.123.123
  10.43.8.67/28:
    - 1.1.1.1
    - 9.9.9.9
```

Use `123.123.123.123` as single upstream DNS resolver for client laptop-home, 
`1.1.1.1` and `9.9.9.9` for all clients in the sub-net `10.43.8.67/28` and 4 resolvers (default) for all others clients.

!!! note

** Blocky needs at least one upstream DNS server **

See List of public DNS servers if you need some ideas, which public free DNS server you could use.

Custom DNS

You can define your own domain name to IP mappings. For example, you can use a user-friendly name for a network printer or define a domain name for your local device on order to use the HTTPS certificate. Multiple IP addresses for one domain must be separated by a comma.

!!! example

```yaml
customDNS:
  mapping:
    printer.lan: 192.168.178.3 
    otherdevice.lan: 192.168.178.15,2001:0db8:85a3:08d3:1319:8a2e:0370:7344
```

This configuration will also resolve any subdomain of the defined domain. For example a query "printer.lan" or " my.printer.lan" will return 192.168.178.3 as IP address.

Conditional DNS resolution

You can define, which DNS resolver(s) should be used for queries for the particular domain (with all sub-domains). This is for example useful, if you want to reach devices in your local network by the name. Since only your router know which hostname belongs to which IP address, all DNS queries for the local network should be redirected to the router.

With the optional parameter rewrite you can replace domain part of the query with the defined part before the resolver lookup is performed.

!!! example

```yaml
conditional:
  rewrite:
    example.com: fritz.box
    replace-me.com: with-this.com
  mapping:
    fritz.box: 192.168.178.1
    lan.net: 192.170.1.2,192.170.1.3
    # for reverse DNS lookups of local devices
    178.168.192.in-addr.arpa: 192.168.178.1
```

In this example, a DNS query "client.fritz.box" will be redirected to the router's DNS server at 192.168.178.1 and client.lan.net to 192.170.1.2 and 192.170.1.3. 
The query client.example.com will be rewritten to "client.fritz.box" and also redirected to the resolver at 192.168.178.1

In this example, a DNS query "client.fritz.box" will be redirected to the router's DNS server at 192.168.178.1 and client.lan.net to 192.170.1.2 and 192.170.1.3.

Client name lookup

Blocky can try to resolve a user-friendly client name from the IP address. This is useful for defining of blocking groups, since IP address can change dynamically. Blocky uses rDNS to retrieve client's name. To use this feature, you can configure a DNS server for client lookup (typically your router). You can also define client names manually per IP address.

Single name order

Some routers return multiple names for the client (host name and user defined name). With parameter clientLookup.singleNameOrder you can specify, which of retrieved names should be used.

Custom client name mapping

You can also map a particular client name to one (or more) IP (ipv4/ipv6) addresses. Parameter clientLookup.clients contains a map of client name and multiple IP addresses.

!!! example

```yaml
clientLookup:
    upstream: 192.168.178.1
    singleNameOrder:
      - 2
      - 1
    clients:
      laptop:
        - 192.168.178.29
```

Use `192.168.178.1` for rDNS lookup. Take second name if present, if not take first name. IP address `192.168.178.29` is mapped to `laptop` as client name.

Blocking and whitelisting

Blocky can download and use external lists with domains or IP addresses to block DNS query (e.g. advertisement, malware, trackers, adult sites). You can group several list sources together and define the blocking behavior per client. External blacklists must be either in the well-known Hosts format or just a plain domain list (one domain per line). Blocky also supports regex as more powerful tool to define patterns to block.

Blocky uses DNS sinkhole approach to block a DNS query. Domain name from the request, IP address from the response, and the CNAME record will be checked against configured blacklists.

To avoid overblocking, you can define or use already existing whitelists.

Definition black and whitelists

Each black or whitelist can be either a path to the local file, a URL to download or inline list definition of a domains in hosts format (YAML literal block scalar style). All Urls must be grouped to a group name.

!!! example

```yaml
blocking:
  blackLists:
    ads:
      - https://s3.amazonaws.com/lists.disconnect.me/simple_ad.txt
      - https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts
      - |
        # inline definition with YAML literal block scalar style
        someadsdomain.com
        anotheradsdomain.com
        # this is a regex
        /^banners?[_.-]/
    special:
      - https://raw.githubusercontent.com/StevenBlack/hosts/master/alternates/fakenews/hosts
  whiteLists:
    ads:
      - whitelist.txt
      - |
        # inline definition with YAML literal block scalar style
        whitelistdomain.com
```

In this example you can see 2 groups: **ads** with 2 lists and **special** with one list. One local whitelist was defined for the **ads** group.

!!! warning

If the same group has black and whitelists, whitelists will be used to disable particular blacklist entries.
If a group has **only** whitelist entries -> this means only domains from this list are allowed, all other domains will
be blocked

Regex support

You can use regex to define patterns to block. A regex entry must start and end with the slash character (/). Some Examples:

  • /baddomain/ will block www.baddomain.com, baddomain.com, but also mybaddomain-sometext.com
  • /^baddomain/ will block baddomain.com, but not www.baddomain.com
  • /^apple\.(de|com)$/ will only block apple.de and apple.com

Client groups

In this configuration section, you can define, which blocking group(s) should be used for which client in your network. Example: All clients should use the ads group, which blocks advertisement and kids devices should use the adult group, which blocky adult sites.

Clients without a group assignment will use automatically the default group.

You can use the client name (see Client name lookup), client's IP address or a client subnet as CIDR notation.

!!! example

```yaml
blocking:
    clientGroupsBlock:
    # default will be used, if no special definition for a client name exists
      default:
        - ads
        - special
      laptop*:
        - ads
      192.168.178.1/24:
        - special
      kid-laptop:
        - ads
        - adult
```

All queries from network clients, whose device name starts with `laptop`, will be filtered against the **ads** group's lists. All devices from the subnet `192.168.178.1/24` against the **special** group and `kid-laptop` against **ads** and **adult**. All other clients: **ads** and **special**.

!!! tip

You can use `*` as wildcard for the sequence of any character or `[0-9]` as number range

Block type

You can configure, which response should be sent to the client, if a requested query is blocked (only for A and AAAA queries, NXDOMAIN for other types):

blockType Example Description
zeroIP zeroIP This is the **
default** block type. Server returns 0.0.0.0 (or :: for IPv6) as result for A and AAAA queries
nxDomain nxDomain return NXDOMAIN as return code
custom IPs 192.100.100.15, 2001:0db8:85a3:08d3:1319:8a2e:0370:7344 comma separated list of destination IP addresses. Should contain ipv4 and ipv6 to cover all query types. Useful with running web server on this address to display the "blocked" page.

!!! example

```yaml
blocking:
  blockType: nxDomain
```

Block TTL

TTL for answers to blocked domains can be set to customize the time (in duration format) clients ask for those domains again. This setting only makes sense when blockType is set to nxDomain or zeroIP, and will affect how much time it could take for a client to be able to see the real IP address for a domain after receiving the custom value.

!!! example

```yaml
blocking:
  blockType: 192.100.100.15, 2001:0db8:85a3:08d3:1319:8a2e:0370:7344
  blockTTL: 10s
```

List refresh period

To keep the list cache up-to-date, blocky will periodically download and reload all external lists. Default period is ** 4 hours**. You can configure this by setting the blocking.refreshPeriod parameter to a value in duration format. Negative value will deactivate automatically refresh.

!!! example

```yaml
blocking:
  refreshPeriod: 60m
```

Refresh every hour.

Download timeout

You can override the default download timeout (duration format) of 60 seconds (for each URL) for big lists or slow internet connection: !!! example

```yaml
blocking:
 downloadTimeout: 4m
```

Caching

Each DNS response has a TTL (Time-to-live) value. This value defines, how long is the record valid in seconds. The values are maintained by domain owners, server administrators etc. Blocky caches the answers from all resolved queries in own cache in order to avoid repeated requests. This reduces the DNS traffic and increases the network speed, since blocky can serve the result immediately from the cache.

With following parameters you can tune the caching behavior:

!!! warning

Wrong values can significantly increase external DNS traffic or memory consumption.
Parameter Type Mandatory Default value Description
caching.minTime duration format no 0 (use TTL) How long a response must be cached (min value). If <=0, use response's TTL, if >0 use this value, if TTL is smaller
caching.maxTime duration format no 0 (use TTL) How long a response must be cached (max value). If <0, do not cache responses. If 0, use TTL. If > 0, use this value, if TTL is greater
caching.maxItemsCount int no 0 (unlimited) Max number of cache entries (responses) to be kept in cache (soft limit). Default (0): unlimited. Useful on systems with limited amount of RAM.
caching.prefetching bool no false if true, blocky will preload DNS results for often used queries (default: names queried more than 5 times in a 2 hour time window). Results in cache will be loaded again on their expire (TTL). This improves the response time for often used queries, but significantly increases external traffic. It is recommended to increase "minTime" to reduce the number of prefetch queries to external resolvers.
caching.prefetchExpires duration format no 2h Prefetch track time window
caching.prefetchThreshold int no 5 Name queries threshold for prefetch
caching.prefetchMaxItemsCount int no 0 (unlimited) Max number of domains to be kept in cache for prefetching (soft limit). Default (0): unlimited. Useful on systems with limited amount of RAM.

!!! example

```yaml
caching:
  minTime: 5m
  maxTime: 30m
  prefetching: true
```

Prometheus

Blocky can expose various metrics for prometheus. To use the prometheus feature, the HTTP listener must be enabled ( see Basic Configuration).

Parameter Mandatory Default value Description
prometheus.enable no false If true, enables prometheus metrics
prometheus.path no /metrics URL path to the metrics endpoint

!!! example

```yaml
prometheus:
  enable: true
  path: /metrics
```

Query logging

You can enable the logging of DNS queries (question, answer, client, duration etc.) to a daily CSV file (can be opened in Excel or OpenOffice Calc) or MySQL/MariaDB database.

!!! warning

Query file/database contains sensitive information. Please ensure to inform users, if you log their queries.

Query log types

You can select one of following query log types:

  • mysql - log each query in the external MySQL/MariaDB database
  • csv - log into CSV file (one per day)
  • csv-client - log into CSV file (one per day and per client)

Configuration parameters:

Parameter Type Mandatory Default value Description
queryLog.type enum (mysql, csv, csv-client (see above)) no Type of logging target. Console if empty
queryLog.target string no directory for writing the logs (for csv) or database url (for mysql)
queryLog.logRetentionDays int no 0 if > 0, deletes log files/database entries which are older than ... days

!!! hint

Please ensure, that the log directory is writable or database exists. If you use docker, please ensure, that the directory is properly
mounted (e.g. volume)

example for CSV format !!! example

```yaml
queryLog:
    type: csv
    target: /logs
    logRetentionDays: 7
```

example for Database !!! example

```yaml
queryLog:
    type: mysql
    target: db_user:db_password@tcp(db_host_or_ip:3306)/db_user?charset=utf8mb4&parseTime=True&loc=Local
    logRetentionDays: 7
```

HTTPS configuration (for DoH)

See Wiki - Configuration of HTTPS for detailed information, how to configure HTTPS.

DoH url: https://host:port/dns-query

--8<-- "docs/includes/abbreviations.md"