# FediBlockHole A tool for keeping a Mastodon instance blocklist synchronised with remote lists. The broad design goal for FediBlockHole is to support pulling in a list of blocklists from a set of trusted sources, merge them into a combined blocklist, and then push that merged list to a set of managed instances. Mastodon admins can choose who they think maintain quality lists and subscribe to them, helping to distribute the load for maintaining blocklists among a community of people. Control ultimately rests with the admins themselves so they can outsource as much, or as little, of the effort to others as they deem appropriate. Inspired by the way PiHole works for maintaining a set of blocklists of adtech domains. Builds on the work of [@CaribenxMarciaX@scholar.social](https://scholar.social/@CaribenxMarciaX) and [@gingerrroot@kitty.town](https://kitty.town/@gingerrroot) who started the #Fediblock hashtag and did a lot of advocacy around it, often at great personal cost. ## Features ### Blocklist Sources - Read domain block lists from other instances via the Mastodon API. - Supports both public lists (no auth required) and 'admin' lists requiring authentication to an instance. - Read domain block lists from arbitrary URLs, including local files. - Supports CSV and JSON format blocklists - Supports RapidBlock CSV and JSON format blocklists ### Blocklist Export/Push - Push a merged blocklist to a set of Mastodon instances. - Export per-source, unmerged block lists to local files, in CSV format. - Export merged blocklists to local files, in CSV format. - Read block lists from multiple remote instances - Read block lists from multiple URLs, including local files - Write a unified block list to a local CSV file - Push unified blocklist updates to multiple remote instances - Control import and export fields ### Flexible Configuration - Provides (hopefully) sensible defaults to minimise first-time setup. - Global and fine-grained configuration options available for those complex situations that crop up sometimes. - Allowlists to override blocks in blocklists to ensure you never block instances you want to keep. - Blocklist thresholds if you want to only block when an instance shows up in multiple blocklists. ## Installing Installable using `pip`. ``` python3 -m pip install fediblockhole ``` Install from source by cloning the repo, `cd fediblockhole` and run: ``` python3 -m pip install . ``` Installation adds a commandline tool: `fediblock-sync` Instance admins who want to use this tool for their instance will need to add an Application at `https:///settings/applications/` so they can authorize the tool to create and update domain blocks with an OAuth token. More on authorization by token below. ### Reading remote instance blocklists If a remote instance makes its domain blocks public, you don't need a token to read them. If a remote instance only shows its domain blocks to local accounts you'll need to have a token with `read:blocks` authorization set up. If you have an account on that instance, you can get a token by setting up a new Application at `https:///settings/applications/`. To read admin blocks from a remote instance, you'll need to ask the instance admin to add a new Application at `https:///settings/applications/` and then tell you the access token. The application needs the `admin:read:domain_blocks` OAuth scope. You can allow full `admin:read` access, but be aware that this authorizes someone to read all the data in the instance. That's asking a lot of a remote instance admin who just wants to share domain_blocks with you. The `admin:read:domain_blocks` scope is available as of Mastodon v4.1.0, but for earlier versions admins will need to use the manual method described below. You can update the scope for your application in the database directly like this: ``` UPDATE oauth_applications as app SET scopes = 'admin:read:domain_blocks' FROM oauth_access_tokens as tok WHERE app.id = tok.application_id AND app.name = '' ; ``` When that's done, regenerate the token (so it has the new scopes) in the application screen in the instance GUI. FediBlockHole should then able to use the app token to read domain blocks via the API, but nothing else. Alternately, you could ask the remote instance admin to set up FediBlockHole and use it to dump out a CSV blocklist from their instance and then put it somewhere trusted parties can read it. Then you can define the blocklist as a URL source, as explained below. ### Writing instance blocklists To write domain blocks into an instance requires both the `admin:read` and `admin:write:domain_blocks` OAuth scopes. The tool needs `admin:read:domain_blocks` scope to read the current list of domain blocks so we update ones that already exist, rather than trying to add all new ones and clutter up the instance. `admin:read` access is needed to check if the instance has any accounts that follow accounts on a domain that is about to get `suspend`ed and automatically drop the block severity to `silence` level so people have time to migrate accounts before a full defederation takes effect. Unfortunately, the statistics measure used to learn this information requires `admin:read` scope. You can add `admin:read` scope in the application admin screen. Please be aware that this grants full read access to all information in the instance to the application token, so make sure you keep it a secret. At least remove world-readable permission to any config file you put it in, e.g.: ``` chmod o-r ``` You can also grant full `admin:write` scope to the application, but if you'd prefer to keep things more tightly secured, limit the scope to `admin:read:domain_blocks`. Again, this scope is only available in the application config screen as of Mastodon v4.1.0. If your instance is on an earlier version, you'll need to use SQL to set the scopes in the database and then regenerate the token: ``` UPDATE oauth_applications as app SET scopes = 'admin:read admin:write:domain_blocks' FROM oauth_access_tokens as tok WHERE app.id = tok.application_id AND app.name = '' ; ``` When that's done, FediBlockHole should be able to use its token to authorise adding or updating domain blocks via the API. ## Using the tool Run the tool like this: ``` fediblock-sync -c ``` If you put the config file in `/etc/default/fediblockhole.conf.toml` you don't need to pass in the config file path. For a list of possible configuration options, check the `--help`. You can also read the heavily commented sample configuration file in the repo at [etc/sample.fediblockhole.conf.toml](https://github.com/eigenmagic/fediblockhole/blob/main/etc/sample.fediblockhole.conf.toml). ## Configuring Once you have your applications and tokens and scopes set up, create a configuration file for FediBlockHole to use. You can put it anywhere and use the `-c ` commandline parameter to tell FediBlockHole where it is. Or you can use the default location of `/etc/default/fediblockhole.conf.toml`. As the filename suggests, FediBlockHole uses TOML syntax. There are 4 key sections: 1. `blocklist_urls_sources`: A list of URLs to read blocklists from 1. `blocklist_instance_sources`: A list of Mastodon instances to read blocklists from via API 1. `blocklist_instance_destinations`: A list of Mastodon instances to write blocklists to via API 1. `allowlist_url_sources`: A list of URLs to read allowlists from More detail on configuring the tool is provided below. ### URL sources The URL sources is a list of URLs to fetch blocklists from. Supported formats are currently: - Comma-Separated Values (CSV) - JSON - Mastodon v4.1 flavoured CSV - RapidBlock CSV - RapidBlock JSON Blocklists must provide a `domain` field, and should provide a `severity` field. `domain` is the domain name of the instance to be blocked/limited. `severity` is the severity level of the block/limit. Supported values are: `noop`, `silence`, and `suspend`. Optional fields that the tool understands are `public_comment`, `private_comment`, `reject_media`, `reject_reports`, and `obfuscate`. #### CSV format A CSV format blocklist must contain a header row with at least a `domain` and `severity` field. Optional fields, as listed about, may also be included. #### Mastodon v4.1 CSV format As of v4.1.0, Mastodon can export domain blocks as a CSV file. However, in their infinite wisdom, the Mastodon devs decided that field names should begin with a `#` character in the header, unlike the field names in the JSON output via the API… or in pretty much any other CSV file anywhere else. Setting the format to `mastodon_csv` will strip off the `#` character when parsing and FediBlockHole can then use Mastodon v4.1 CSV blocklists like any other CSV formatted blocklist. #### JSON format JSON is also supported. It uses the same format as the JSON returned from the Mastodon API. This is a list of dictionaries, with at minimum a `domain` field, and preferably a `severity` field. The other optional fields are, well, optional. #### RapidBlock CSV format The RapidBlock CSV format has no header and a single field, so it's not _strictly_ a CSV file as there are no commas separating values. It is basically just a list of domains to block, separated by '\r\n'. When using this format, the tool assumes the `severity` level is `suspend`. #### RapidBlock JSON format The RapidBlock JSON format provides more detailed information about domain blocks, but is still somewhat limited. It has a single `isBlocked` flag indicating if a domain should be blocked or not. There is no support for the 'silence' block level. There is no support for 'reject_media' or 'reject_reports' or 'obfuscate'. All comments are public, by virtue of the public nature of RapidBlock. ### Instance sources The tool can also read domain_blocks from instances directly. The configuration is a list of dictionaries of the form: ``` { domain = '', token = '', admin = false } ``` The `domain` is the fully-qualified domain name of the API host for an instance you want to read domain blocks from. The `token` is an optional OAuth token for the application that's configured in the instance to allow you to read domain blocks, as discussed above. `admin` is an optional field that tells the tool to use the more detailed admin API endpoint for domain_blocks, rather than the more public API endpoint that doesn't provide as much detail. You will need a `token` that's been configured to permit access to the admin domain_blocks scope, as detailed above. ### Instance destinations The tool supports pushing a unified blocklist to multiple instances. Configure the list of instances you want to push your blocklist to in the `blocklist_instance_detinations` list. Each entry is of the form: ``` { domain = '', token = '', import_fields = ['public_comment'], max_severity = 'suspend', max_followed_severity = 'suspend' } ``` The fields `domain` and `token` are required. The fields `max_followed_severity` and `import_fields` are optional. The `domain` is the hostname of the instance you want to push to. The `token` is an application token with both `admin:read:domain_blocks` and `admin:write:domain_blocks` authorization. The optional `import_fields` setting allows you to restrict which fields are imported from each instance. If you want to import the `reject_reports` settings from one instance, but no others, you can use the `import_fields` setting to do it. **Note:** The `domain` and `severity` fields are always imported. The optional `max_severity` setting limits the maximum severity you will allow a remote blocklist to set. This helps you import a list from a remote instance but only at the `silence` level, even if that remote instance has a block at `suspend` level. If not set, defaults to `suspend`. The optional `max_followed_severity` setting sets a per-instance limit on the severity of a domain_block if there are accounts on the instance that follow accounts on the domain to be blocked. If `max_followed_severity` isn't set, it defaults to `silence`. This setting exists to give people time to move off an instance that is about to be defederated and bring their followers from your instance with them. Without it, if a new `suspend` block appears in any of the blocklists you subscribe to (or a block level increases from `silence` to `suspend`) and you're using the default `max` mergeplan, the tool would immediately suspend the instance, cutting everyone on the blocked instance off from their existing followers on your instance, even if they move to a new instance. If you actually want that outcome, you can set `max_followed_severity = 'suspend'` and use the `max` mergeplan. Once the follow count drops to 0 on your instance, the tool will automatically use the highest severity it finds again (if you're using the `max` mergeplan). ### Allowlists Sometimes you might want to completely ignore the blocklist definitions for certain domains. That's what allowlists are for. Allowlists remove any domain in the list from the merged list of blocks before the merged list is saved out to a file or pushed to any instance. Allowlists can be in any format supported by `blocklist_urls_sources` but ignore all fields that aren't `domain`. You can also allow domains on the commandline by using the `-A` or `--allow` flag and providing the domain name to allow. You can use the flag multiple times to allow multiple domains. It is probably wise to include your own instance domain in an allowlist so you don't accidentally defederate from yourself. ## More advanced configuration For a list of possible configuration options, check the `--help` and read the sample configuration file in `etc/sample.fediblockhole.conf.toml`. ### save_intermediate This option tells the tool to save the unmerged blocklists it fetches from remote instances and URLs into separate files. This is handy for debugging, or just to have a non-unified set of blocklist files. Works with the `savedir` setting to control where to save the files. These are parsed blocklists, not the raw data, and so will be affected by `import_fields`. The filename is based on the URL or domain used so you can tell where each list came from. ### savedir Sets where to save intermediate blocklist files. Defaults to `/tmp`. ### blocklist_auditfile If provided, will save an audit file of counts and percentages by domain. Useful for debugging thresholds. Defaults to None. ### no_push_instance Defaults to False. When set, the tool won't actually try to push the unified blocklist to any configured instances. If you want to see what the tool would try to do, but not actually apply any updates, use `--dryrun`. ### no_fetch_url Skip the fetching of blocklists from any URLs that are configured. ### no_fetch_instance Skip the fetching of blocklists from any remote instances that are configured. ### override_private_comment Defaults to None. Stamp all *new* blocks pushed to a remote server with this comment or code. Helps to identify blocks you've created on a server via this process versus ones that already existed. ### mergeplan If two (or more) blocklists define blocks for the same domain, but they're different, `mergeplan` tells the tool how to resolve the conflict. `max` is the default. It uses the _highest_ severity block it finds as the one that should be used in the unified blocklist. `min` does the opposite. It uses the _lowest_ severity block it finds as the one to use in the unified blocklist. A full discussion of severities is beyond the scope of this README, but here is a quick overview of how it works for this tool. The severities are: - **noop**, level 0: This is essentially an 'unblock' but you can include a comment. - **silence**, level 1: A silence adds friction to federation with an instance. - **suspend**, level 2: A full defederation with the instance. With `mergeplan` set to `max`, _silence_ would take precedence over _noop_, and _suspend_ would take precedence over both. With `mergeplan` set to `min`, _silence_ would take precedence over _suspend_, and _noop_ would take precedence over both. You would want to use `max` to ensure that you always block with whichever your harshest fellow admin thinks should happen. You would want to use `min` to ensure that your blocks do what your most lenient fellow admin thinks should happen. ### import_fields `import_fields` controls which fields will be imported from remote instances and URL blocklists, and which fields are pushed to instances from the unified blocklist. The fields `domain` and `severity` are always included, so only define extra fields, if you want them. You can't export fields you haven't imported, so `export_fields` should be a subset of `import_fields`, but you can run the tool multiple times. You could, for example, include lots of fields for an initial import to build up a comprehensive list for export, combined with the `--no-push-instances` option so you don't actually apply the full list to anywhere. Then you could use a different set of options when importing so you have all the detail in a file, but only push `public_comment` to instances. ### export_fields `export_fields` controls which fields will get saved to the unified blocklist file, if you export one. The fields `domain` and `severity` are always included, so only define extra fields, if you want them.