Key concepts
The terms below appear throughout the web interface. Each section links to the page that covers it in full.
Set
A set ties a list of targets to what b4 does with their traffic. b4 changes nothing until a set targets sites. Sets are created on the Sets page or from a Discovery result, see Sets.
Target
Targets decide which traffic a set applies to: domains, IP addresses and ranges, GeoSite and GeoIP categories, ASNs and source devices. They are edited on the set's Targets tab, see Targets. How sets match traffic explains which set handles a connection that several sets match.
Strategy
A strategy is the set of packet changes a bypass set makes, such as splitting a request into pieces or sending fake packets ahead of it. It is configured on the set's TCP and UDP tabs, see TCP. Discovery tests strategies and suggests the one that loaded the sites.
Set kinds
The dashboard shows each set's kind. Enable Routing and Routing mode on the set's DNS & Routing tab decide it.
| Kind | Setting | What the set does |
|---|---|---|
| Bypass | Enable Routing off | Applies its strategy to its traffic. See Unblocking a site |
| Route | Network interface | Sends its traffic out through another interface, such as a VPN. See Routing sites through a VPN or another interface |
| Proxy | Upstream SOCKS5 proxy or Telegram over WebSocket (built-in) | Hands its traffic to a SOCKS5 proxy, or to b4's Telegram bridge. See Sending sites through a SOCKS5 proxy |
| Block | Block (blackhole) | Stops its traffic, for every device and for the router itself. See Blocking ads and sites |
A proxy set applies no strategy, and neither does a route set whose interface is a tunnel such as a VPN: the tunnel or the proxy carries the traffic to the site. A set routed to a plain interface, such as a second uplink, keeps its strategy, see Network interface.
Discovery
Discovery tests b4's strategies against sites that do not open. It turns the strategy that loaded them into a new set, or writes it into an existing one. It is the usual way to make a first set, see First steps and Discovery.
Watchdog
The watchdog fetches a set's pages on a schedule. When they keep failing, it runs Discovery for the set and writes the new strategy into it. It is turned on under Settings > Discovery, and for each set with Keep this set working with the watchdog on the set's Discovery tab. See Watchdog.
Escalation
Escalation moves a site to a backup set when its own set keeps failing to reach it, and tries the original set again after a while. The backup can use another strategy, a VPN or a proxy. The watchdog repairs a whole set on a schedule, while escalation reacts to the failing connections of one site. It is set up on the set's Escalation tab, see Escalation.
Community sets
Community sets are sets that other b4 users published to the Community Hub. The Community page lists them, applies one in one step, and collects reports on whether it works. An applied set is a normal set marked Community set. The page appears once Enable Community Hub is on under Settings > Integrations, see Community.
Packet engine
The packet engine is how traffic reaches b4:
- NFQUEUE, the default, has firewall rules hand packets to b4.
- TUN interface routes the traffic through a virtual interface instead. It is the alternative on kernels without the NFQUEUE modules.
Either way, b4 reads only the first packets of each connection. The engine is chosen under Settings > Core > Packet Engine and changes after a restart, see Packet engine. When the engine does not start, the dashboard shows the error and offers the other engine.