# hive-network The bridge every container on a host attaches to, and the private-netns isolation of agent and CI containers behind it. It comes up on any host that runs agents or swarm services: `services.hyperhive.network.enable` defaults to off, and the modules that need the bridge set it with `mkDefault true` — the hive controller, CI, the hive collector, and the gateway's resolver, which every swarm service turns on. Configured via `services.hyperhive.network.*`. Agent containers always run in a private netns. ## Network map One picture of the whole hive — two planes: **infra containers share the host netns** and bind host ports directly; **compute containers (agents + CI) each get a private netns** behind the bridge. The unix-socket control plane rides the VFS, and none of that touches it. ``` internet │ uplink NIC — NAT MASQUERADE for the │ bridge subnet (10.42.0.0/24 default) ┌──────────────────────────┴─────────────────────────────────────────┐ │ host netns — the host itself plus gateway / forge │ │ │ │ nginx :80/:443 [hive-gateway] │ │ dnsmasq 10.42.0.1:53 (DNS) + :67 (DHCP) [hive-gateway] │ │ squid 10.42.0.1:3128 (egress proxy) [hive-squid] │ │ forgejo :3000 http, :2222 git-ssh [hive-forge] │ │ hive-c0re dashboard 127.0.0.1:7000 (host service) │ │ wg-hive :51820/udp — swarm mesh, when enabled (host iface) │ │ │ │ hive-br0 10.42.0.1/24 │ │ ┌──────────┼──────────────┐ │ └──────────────┼──────────┼──────────────┼───────────────────────────┘ vb-h- vb-h- vb- veth pairs │ │ │ ┌────┴────┐ ┌───┴─────┐ ┌──────┴──┐ one private netns │ agent a │ │ agent b │ │ runner │ each; eth0 leases │ eth0 │ │ eth0 │ │ eth0 │ from the DHCP pool └─────────┘ └─────────┘ └─────────┘ ``` | container | netns | IPv4 | listens / reached via | | ------------------------- | ----------------------- | -------------- | ----------------------------------------------------------------------------------------------- | | gateway (host) | host | host addresses | nginx `:80`/`:443` (every vhost); dnsmasq `bridgeIp:53` + DHCP `:67` on the bridge | | egress proxy (host) | host | `bridgeIp` | squid `bridgeIp:3128`; agents with a credential send HTTP and HTTPS through it | | `hive-forge` | host (shared) | host addresses | forgejo `:3000` http, `:2222` git-ssh; fronted by the `forge.` vhost | | `hive-matrix` | private, veth on bridge | DHCP pool | tuwunel on UDS `/run/hive-matrix/tuwunel.sock` → the matrix vhost; out to store, SSO, peers | | `swarm-ci-runner` | private, veth on bridge | DHCP pool | outbound only (runner → forge); no inbound surface | | `swarm-review-classifier` | private, veth on bridge | DHCP pool | outbound only (classifier → queue, secret store, swarm collector); no inbound surface | | `h-` | private, veth on bridge | DHCP pool | web UI via UDS `/run/hive-agent/` → nginx sub-path; in-container UI port hashed 8100–8999 | The flows, end to end: - **DHCP** — agent `dhcpcd` broadcasts on `eth0` → veth → bridge → host firewall (udp 67 hole) → dnsmasq pool → lease + router option. `dhcpcd` runs with `noipv4ll` and waits for an IPv4 address, so `network-online.target` means a lease, never a 169.254.x fallback; units that look up a swarm name at start order after it. - **DNS** — agents and the service containers query `bridgeIp:53`; dnsmasq answers hive zones authoritatively with the bridge IP, everything else forwards to the host's resolvers (see _Resolver behaviour_ below). Each container points its own `resolv.conf` there, and one that instead inherits the host's resolves no swarm name at all — those records exist only on the bridge. - **HTTP** — `forge.` and `chat.` (under `swarm.domain`) plus the hive's own dashboard name resolve to the bridge IP, land on nginx `:80`/`:443`, and proxy to forgejo `:3000`, tuwunel's unix socket, hive-c0re `127.0.0.1:7000`, or a per-agent UI unix socket. - **Internet egress** — agent default route points at the bridge IP; the host forwards + masquerades out its uplink. - **Swarm** — peer hives connect over the `wg-hive` WireGuard mesh and reach each other's gateway/forge across it ([`docs/2-handbook/swarm/`](../../2-handbook/swarm/README.md)). - **Control plane (no network)** — per-agent broker socket `/run/hive/mcp.sock`, privileged helper `/run/hive/priv.sock`, operator admin `/run/hyperhive/host.sock`, and the per-agent UI sockets under `/run/hive-agent/` are unix domain sockets bind-mounted through the VFS; private netns doesn't affect them. ## Container shape (where dnsmasq lives) dnsmasq runs on the host itself, next to nginx — both come from the gateway module, one front door for DNS and HTTP. Its `bind-interfaces` listener sits on `bridgeIp`, on the host's bridge interface. ## Configuration ```nix { services.hyperhive = { swarm = { domain = "myswarm.example"; hives.firsthive = { }; # -> domain = firsthive.myswarm.example }; deploy.hive-controller = { enable = true; hiveName = "firsthive"; }; # network.bridgeIp = "10.42.0.1"; # default }; } ``` The hive domain (`services.hyperhive.domain`, which the resolver answers for) comes from this hive's entry in the swarm directory: `swarm.hives..domain`, default `.`. Eval fails until `swarm.domain` and that entry exist ([`2-handbook/swarm/README.md`](../../2-handbook/swarm/README.md) § Hive identity config). ## Bridge addressing Default subnet is `10.42.0.0/24`, host-side gateway at `10.42.0.1`. RFC 1918 space, unlikely to clash with operator's existing setup; override `bridgeIp` + `bridgePrefixLength` if a different range is already in use. `/24` gives 254 usable per-agent addresses — enough for any single-host hive; bigger swarms or tighter addressing schemes pick their own. ## Resolver behaviour dnsmasq is **authoritative** for the hive's own zone (``) plus whatever swarm-service names this host contributes via `gateway.localNames` — `forge.` and `chat.` (matrix) when this host runs those services, `auth.` when it runs authelia, and `hive-collector.hive` on every hive — answering each with the bridge IP (where nginx is reachable, and where the hive's own collector listens). Note forge and matrix are swarm-domain names, not sub-domains of ``: a swarm runs one forge and one homeserver, so their names belong to the swarm rather than to whichever hive happens to host them. Every domain answered this way is also `local=` for dnsmasq, so the other record types (AAAA, TXT, MX, HTTPS) for those names get an empty answer from dnsmasq itself instead of waiting on the host's upstream resolver. Without it, dnsmasq 2.86 and later send them upstream, and a host whose upstream doesn't answer leaves each lookup to its client's own timeout. dnsmasq forwards everything else to the host's own resolvers: it runs on the host and reads the host's `/etc/resolv.conf` directly. Containers don't need to know the upstream — they query the bridge IP and dnsmasq does the right thing per-name. No fallback `server=` exists, by design: dnsmasq queries all known upstreams in parallel, so a hardcoded public resolver would take a share of normal traffic, not just cover the gap. dnsmasq runs on the host and reads the host's `/etc/resolv.conf` directly, so a network change (new router, new lease, laptop moving networks) reaches it the moment openresolv rewrites the file. Nothing needs synchronising, and no unit watches for it. `bind-interfaces` + `interface = [ bridgeName "lo" ]` means the listener only accepts queries from the bridge interface (plus lo for container health-checks). External hosts can't reach it — no DNS-amplification surface even when the operator opens port 80 for gateway HTTP. `resolveLocalQueries = false` keeps dnsmasq out of the host's own resolution stack — the host's resolver (systemd-resolved, plain glibc nss, dnscrypt-proxy, etc.) keeps doing whatever the operator configured. The hive resolver is purely for inbound queries from agent containers. ## Firewall posture `networking.firewall.interfaces..allowedUDPPorts = [ 53 67 ]` `networking.firewall.interfaces..allowedTCPPorts = [ 53 80 443 ]` - Port 53 opens the resolver on the bridge interface only. Other interfaces stay closed. The hive resolver isn't an external-facing service. - Port 67 (UDP) admits DHCP requests to the dnsmasq pool. dnsmasq receives DHCP via a regular UDP socket (it doesn't use a netfilter-bypassing raw socket), so the hole is mandatory — without it containers never get a lease and fall back to 169.254.x.x. - Ports 80 and 443 let isolated agents reach nginx (on the host) for the forge sub-domain, per-agent UI proxies, and any other HTTP services. The **host** firewall is the only firewall. The swarm service containers that share the host netns (forge, bao, the metrics and log stores) run with `networking.firewall.enable = false` (`nix/container-modules/swarm-container.nix`): a NixOS firewall inside a shared-netns container runs against the _host_ ruleset — at container boot its `firewall-start` flushes the `nixos-fw` chains, rebuilds them from the container's (empty) port list, and deletes the host's `nixos-nat-*` chains without recreating them, silently wiping the bridge holes above plus the agents' NAT. Private-netns containers (every container with `privateNetwork = true`: agents and the service containers on the bridge) keep their own firewall — it's scoped to their namespace. ### Reaching host services (`exposeHostPorts`) By default agents can only reach the host on 80/443 (+53 DNS), so a host-side service on another port — for example a dev OTLP collector you want agents to reach directly — is unreachable. (hyperhive's own services need none of this: a module that means to be reachable from agents opens its own port here, which the hive collector and `nats.enable` both do. Note that `deploy.swarm-otel.upstream.endpoint` is the _upstream_, which no agent ever dials. See `docs/4-implementation/scheduler/observability.md`.) `services.hyperhive.network.exposeHostPorts = [ 4318 ];` opens each listed TCP port `P` on the bridge-interface `allowedTCPPorts`, so an agent can connect to `:P` (for a dev OTLP collector, point its endpoint at `http://:4318`, default `http://10.42.0.1:4318`). The hive's own collector needs none of this: agents dial it by `otel.collector.host`. This is **firewall-only**: the host service must bind an address reachable from the bridge — `0.0.0.0` or the bridge IP — not loopback only. The bridge→`127.0.0.0/8` DROP rule (below) still applies, so a service bound to `127.0.0.1` only stays unreachable; rebind it to `0.0.0.0`. The port is reachable by **every** agent on the bridge subnet (like DNS/gateway), so only expose services safe for any agent to reach. ## Egress proxy (squid) Every hive host runs squid in the host netns, listening on `:3128` (`nix/host-modules/hive-squid.nix`). The port is open on the bridge interface only. An agent sends its outbound HTTP and HTTPS through it once its hive says the proxy is ready and it has fetched its proxy credential (see _Agents and the proxy_ below). A program that ignores the proxy variables still reaches squid when it speaks HTTP on port 80 or TLS on port 443 and its agent is `restricted` or in `log` mode: the host redirects that traffic into squid's intercept ports (see _Intercepted web traffic_ below). Everything else goes straight out through the NAT, as before: the `unrestricted` agents, the service containers and every other port and protocol. Nothing blocks that yet. The host logs those direct connections (see _Agent bridge egress log_ below). Squid filters on the destination hostname: a `CONNECT` target or a plain-HTTP host. It never decrypts TLS. The one TLS key it loads is a throwaway that the unit generates at each start, that signs nothing and that no agent trusts. It caches nothing. - **Credentials.** A request for a listed name must carry a per-agent proxy credential (HTTP Basic, the agent's name and its secret). `swarm-controller` mints one per agent at `swarm/agents//proxy-credential`, and never replaces it. `hive-c0re` hashes the credentials of this hive's agents, and one more for the self-check, into `services.hyperhive.deploy.hive-controller.squid.usersFile` every 30 seconds. Squid's `basic_ncsa_auth` helper re-reads the file when it changes. A stopped agent stays in the file. Squid caches a good login for a minute. Nothing rotates a credential: to replace one, delete its leaf in the store and the next pass mints a new one. HTTP Basic crosses the bridge in clear between an agent and the proxy. See [the credentials reference](../../4-implementation/swarm/credentials-reference.md). A request without a valid credential gets a 407, once the destination checks below have passed it. - **Agents and the proxy.** An agent uses the proxy only when its hive says this host's squid is ready for it. `hive-c0re` puts two facts in every container's `/etc/hyperhive-hive-facts`, only on a hive that holds a store identity: `HIVE_SQUID_PROXY` (`services.hyperhive.deploy.hive-controller.squid.listen`, the bridge IP and port) and `HIVE_EGRESS_NO_PROXY` (the direct hosts below). A hive that predates them writes neither, and its agents go direct. `hive-agent-proxy-credential.service` (`nix/agent-modules/egress-proxy.nix`) runs in each agent's container, as the agent user, at start and every 10 minutes. With both facts present it logs in to the secret store with the agent's own certificate, reads `swarm/agents//proxy-credential` and writes `/run/hive-agent-proxy-credential/proxy.env` (`0600`) with `HTTPS_PROXY`, `HTTP_PROXY`, their lower-case forms, `NODE_USE_ENV_PROXY=1` and `NO_PROXY`/`no_proxy`. The proxy URL is `http://:@:3128`; Claude Code, Node, curl, git and reqwest send the userinfo as `Proxy-Authorization`. The harness, its bash tool, the subagents, the MCP servers and the pollers load the file with `EnvironmentFile=-` when they start. Until the facts and the credential both exist nothing writes the file, so those units have no proxy variable and go direct; a failed read keeps the file already in place. Nothing restarts on deploy: an agent takes the proxy at its next start, which is its next rebuild or restart. The credential is in the environment of every process those units start, so `env` in the agent's shell prints it. Login shells (`nixos-container root-login`, SSH) don't load the file. - **Direct destinations.** `HIVE_EGRESS_NO_PROXY` is the hosts this agent must reach without the proxy, and `NO_PROXY` is `localhost,127.0.0.1,::1` followed by that list. `hive-c0re` computes it from the host's options: the bridge IP, the hive's domain (`services.hyperhive.domain`), the secret store and queue names (`services.hyperhive.swarm.bao.domain`, `swarm.nats.domain`), `services.hyperhive.swarm.serviceDomains` (the swarm UI and controller apex, the forge, matrix, attic, logs, metrics and otel names) and every name the gateway answers with the bridge IP (`services.hyperhive.gateway.localNames`). Squid refuses every destination that resolves to the bridge, and the hive's resolver answers the bridge address for those names, so they never go through the proxy. A bare name matches itself and its subdomains. Node's `NO_PROXY` has no CIDR support, so the list holds the bridge as an address. - **Two lists.** The credential decides the policy. `hive-c0re` writes a second file beside the users file, `services.hyperhive.deploy.hive-controller.squid.unrestrictedFile` (`/var/lib/hive-squid/unrestricted`, `hive-core:squid`, `0640`): the names of the users whose agent holds the `unrestricted_internet` flag in the permissions the hive last read from the swarm, one per line, rewritten when it changes. The default is permissive: an agent with no record, or a record that never set the flag, holds it, the same default as the `hyperhive.agent.unrestricted_internet` metric. While the hive's read of the permissions is stale or failing, a new agent that already holds a credential counts as unrestricted. Squid reads the list when it parses its configuration, so `squid-unrestricted-reload.path` reloads squid when the file changes. A missing or empty file lists no one, and squid starts either way. A flag change reaches squid after the hive's next read of the permissions and its next 30-second pass. An older `hive-c0re` writes no list, so every credential on that hive is restricted. Agents must not start sending credentials until every hive runs the `hive-c0re` that writes it, or a legacy agent loses general internet. - **Log mode.** The operator can put an agent in `log` mode in the swarm UI. Its record keeps `unrestricted_internet` at `false` and adds `internet_log: true`, so a `hive-c0re` that doesn't know the field still enforces the list. For such an agent `hive-c0re` adds to `agent-allow.conf`, after the allow rules for every agent's own names, `http_access allow !icpt !allowed_dst log_mark` and the same rule for the intercept ports, where `log_mark` is an `annotate_transaction` ACL that sets `would_deny=1`. The rules come last in the include, so every destination deny and `deny !icpt !authed` before them still applies, and a name the agent may reach never carries the mark. A request the rule lets through gets a second log line, `would_deny user= method= host= port=

result=`, from the `would_denied` `access_log` in `hive-squid.nix`; the usual request line keeps its format. The **would-deny** tab of the `egress` dashboard in Grafana lists the hosts per agent. Only the operator changes the mode: nothing moves an agent to `restricted` after a time or a count. The self-check's users aren't agents, so `deny-canary.invalid` stays a 403. - **Modes.** An agent is in one of three modes, and the deny list (next bullet) applies in all of them: | mode | the deny list | a name not on the allow list | | -------------- | ------------- | ---------------------------- | | `restricted` | blocked | blocked | | `log` | blocked | allowed and logged | | `unrestricted` | blocked | allowed | - **Deny list.** The swarm's deny list names destinations the proxy refuses whatever else allows them. The swarm controller keeps it as its own value (the `deny` key of the `egress-allow` bucket), each entry for every agent or for one, and serves it at `GET`/`POST`/`DELETE /api/egress/denied-domains` with the same body as the allow-list (`{"domain": ".example.com", "agent": "atlas"}`). Write a name as in the allow-list: at least two labels, one leading dot for the name and its subdomains. The controller refuses IP addresses, other wildcards, ports and paths. Unlike the allow-list it doesn't refuse the base list's names: denying one is the point. Every 30 seconds `hive-c0re` reads the list and renders `services.hyperhive.deploy.hive-controller.squid.denyFile` (`/var/lib/hive-squid/deny.conf`, `hive-core:squid`, `0640`) for the agents it runs, and `squid-unrestricted-reload.path` reloads squid when it changes. - **Precedence.** The configuration includes the file after the destination denies and before `deny !icpt !authed` and every allow, so a denied name is refused even when the base list, the hive's `allowedDomains`, the swarm's allow-list, the unrestricted flag or `log` mode would allow it. A swarm-wide entry names no user, so every client gets a 403 for it, one without a credential too. An agent's entry also names the agent's squid user, so it binds that agent: a client that sent no credential gets the usual 407 for it. An agent's entry only adds to the swarm-wide ones; no entry of one scope lifts another. - **Log line.** A request a deny rule refused gets a second log line, `egress_denied user= method= host= port=

result=`, in every mode. It differs from the `would_deny` line of `log` mode and from the `TCP_DENIED/403` line every refusal has, so you can tell a deny-list hit from a name that isn't on the allow-list. - **Who writes it.** Only an operator's request to the controller writes the list. It has no automatic entries: nothing derives a deny from an agent's API-key environment or a linked account, and the stored type has no such field. An agent has no queue grant that reaches the key, and the controller's API sits behind the operator's SSO login: nginx checks it before it hands a request to the socket, which only nginx and root can open. - **Empty list.** With no entry `deny.conf` is empty and squid configures as it did without the list: the configuration gains one `include` line and the `egress_denied` log lines, and no rule. A hive on a `hive-c0re` that predates the list never reads the key and keeps its old configuration, so nothing on its wire changes. - **Applied.** Each hive reports the revision of the list it last rendered as `egress_deny_applied` in its status snapshot (see [the hive snapshot](../../2-handbook/swarm/README.md)). `GET /api/egress/denied-domains` answers the list's `revision` and `behind`, the hives that haven't reported it: an older `hive-c0re` never does, so it shows there rather than silently allowing the names. A hive that reads the list reports within about a minute. Reporting means the file holds the rules; squid reloads moments later. - **Base list.** `services.hyperhive.deploy.hive-controller.squid.baseAllowedDomains` is open to every authenticated user, whatever its flag: what the agent harness needs off the swarm. The default is the hosts Claude Code requires (): `api.anthropic.com` for the model API and the usage probe (`hive-agent/src/claude_usage_watch.rs`), `claude.ai` for the account login, and `platform.claude.com` for the OAuth token exchange and refresh. An agent whose `ANTHROPIC_BASE_URL` points elsewhere needs no entry here: the swarm controller adds that host to the agent's own swarm entries (see _Swarm allow-list_ below). The list omits the plugin marketplace clone from `github.com`, since a failed add isn't fatal. The rules below still refuse an entry that resolves to a private address. - **Allow-list.** `services.hyperhive.deploy.hive-controller.squid.allowedDomains` defaults to empty, plus the self-check canary (`services.hyperhive.deploy.hive-controller.squid.selfcheck.canary`), so the canary widens the restricted list by that one name. The swarm's own service names aren't on it: they resolve to the bridge or a private address, which the rules below refuse, and agents reach them directly. Each entry matches that exact name, or with a leading dot the name and its subdomains. A user on the unrestricted list reaches any other name too, on ports 80 and 443. Everyone else gets a 403 for it. `allowedDomains` is the hive's own list, always allowed whether or not the swarm has a list of its own (next bullet). - **Swarm allow-list.** The operator adds domains in the swarm UI ([allowed domains](../web-ui/swarm-ui.md#allowed-domains)); the swarm controller keeps them in one value of the `egress-allow` bucket, each for every agent or for one agent. Every 30 seconds `hive-c0re` reads it and writes two files beside the users file, `services.hyperhive.deploy.hive-controller.squid.allowedFile` (`/var/lib/hive-squid/allowed`) and `services.hyperhive.deploy.hive-controller.squid.agentAllowFile` (`/var/lib/hive-squid/agent-allow.conf`), `hive-core:squid`, `0640`, and logs `squid allow list: 2 swarm, 3 agent entries` when they change. The swarm-wide names join the allow ACL, so a restricted user reaches them. A per-agent entry is a rule for that agent's squid user, `http_access allow !icpt `, and a second one for the user the intercept helper names (`icpt `), in the generated `agent-allow.conf` that the configuration includes at the point where the base list gets its allow: after every destination deny and `deny !icpt !authed`, so the rules under _Denied before any allow_ still bind it, and before the unrestricted rule. Only this hive's agents get a rule. `squid-unrestricted-reload.path` reloads squid when either file changes, so there is no deploy or restart. A name is a DNS name of at least two labels. One leading dot (`.example.com`) also allows every subdomain, and is the only wildcard; the controller refuses IP addresses, other wildcards, ports, paths and the base list's names when you add the entry, and `hive-c0re` checks each name again and skips one that fails, or that the base list or the canary covers, or that another entry of the same list covers. A name that resolves to a private address stays a 403. The controller also adds entries itself, and only from the operator's own actions in the swarm UI. Saving an agent's API-key environment makes it take the host from `ANTHROPIC_BASE_URL` and from every variable named `*_BASE_URL` (the address an ACP agent that loads the same file reads), and keeps one `derived` entry for that agent per host. Each host passes the same check as an operator's entry, so an IP address, `localhost` and a base-list name get none. A save or a delete of the environment replaces the agent's derived entries, and destroying the agent drops all its entries. The agent can create its own `backend-env` leaf while the leaf is empty, so text found in the store never creates an entry: when the controller starts, it only drops derived entries whose exact host the stored environment no longer names, and logs a host it didn't derive. An environment saved before this existed gets its entries when the operator saves it once more. An agent on the hand-placed `backendEnvironmentFile` alone, and the `opencode` preset's `acp.opencode.provider.baseUrl`, get no derived entry, so add one in the swarm UI. A `hive-c0re` that predates the field renders a derived entry like any other. Linking a GitHub token, an external matrix account or an external forge account adds a derived entry for that agent per host it reaches, and deleting the account removes it: `github.com`, `api.github.com`, `raw.githubusercontent.com`, `codeload.github.com` and `objects.githubusercontent.com` for GitHub, and the host of the matrix account's `homeserver` or the forge account's `url`. Each entry's `source` (`link:github`, `link:matrix:`, `link:forge:

:443 `, before the ClientHello, then the `CONNECT :443 ` line with `TCP_TUNNEL/200` or `TCP_DENIED/403` (`NONE_NONE/409` when the SNI and the address disagree). An intercepted HTTP request logs `GET http:/// `. A tunnel to an intercepted destination ends in `ORIGINAL_DST/
`. `cache.log` notes an ACL that met a flow squid refused before its request. - **Rollout.** The redirect, squid's configuration and `hive-priv` ship in one build. A hive that still runs an older build has no redirect, and its agents go direct as before. The agents that use the proxy variables see no change. ## Container isolation Each agent container runs in a private network namespace with a dedicated veth pair attached to the bridge. The following table summarises what the nix side sets up unconditionally: | effect | mechanism | | -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | IP forwarding | `boot.kernel.sysctl."net.ipv4.ip_forward" = 1` | | Internet NAT | `networking.nat { enable = true; internalInterfaces = [ bridgeName ]; }` — MASQUERADE on packets leaving via any external NIC | | Loopback DROP | `nix/host-modules/hive-egress.nix` — own nftables table `inet hive_egress` (whichever firewall the host runs): drops bridge → `127.0.0.0/8` and `::1` traffic; the kernel default `route_localnet=0` is the first layer | | Forward log | `nix/host-modules/hive-egress.nix` — the same table's `forward` chain logs and counts what the host routes from the bridge to the uplink; it blocks nothing (see _Agent bridge egress log_ below) | | Source check | `nix/host-modules/hive-egress.nix` — the `bridge hive_egress` table drops a frame whose source MAC or address differs from the sending container's own (see _Agent bridge source check_ below) | | Gateway access | `networking.firewall.interfaces..allowedTCPPorts = [ 80 443 ]` — lets isolated agents (private netns, veth on bridge) reach nginx on the host | | c0re signal | `HIVE_NETWORK_BRIDGE`, `HIVE_NETWORK_SUBNET` in `systemd.services.hive-c0re.environment` — both **required**; `hive-c0re` refuses to start without them | `HIVE_NETWORK_SUBNET` is the host-side bridge IP + prefix (e.g. `10.42.0.1/24`), **not** the canonical network address. The Rust side must normalise (bitwise-AND with mask) before subnet membership checks or address arithmetic. ### What the Rust side does `hive-c0re` reads `HIVE_NETWORK_BRIDGE` + `HIVE_NETWORK_SUBNET` and passes `PRIVATE_NETWORK=1`, `LOCAL_ADDRESS=` (empty), `HOST_ADDRESS=`, and `HOST_BRIDGE=` when creating or updating containers: `lifecycle::set_nspawn_flags` hands them to hive-priv, which rewrites `/etc/nixos-containers/.conf`. hive-c0re validates both variables **once at daemon startup**, not per container: they're process-global, so a missing or malformed value is a misconfigured daemon rather than one bad container, and failing at boot gives a single diagnostic instead of one per agent. No non-isolated mode exists to fall back to. hive-c0re leaves `LOCAL_ADDRESS` empty so the container's dhcpcd acquires an address from the bridge dnsmasq pool (`networking.useDHCP = true` in `nix/agent-modules/network.nix`). This applies to every agent container, manager included. `HOST_ADDRESS` is the bridge gateway IP (the address part of `HIVE_NETWORK_SUBNET`, via `lifecycle::bridge_gateway_ip` — taken verbatim so a non-`.1` operator override still resolves to wherever the bridge actually lives). It's **load-bearing**: nixos-container's container-side network setup only installs a default route (`ip route add default via $HOST_ADDRESS`) when `HOST_ADDRESS` is non-empty. In bridge mode nixos-container skips the host-side address/route setup, so writing it only affects the container's default route — without it the container comes up with an IP but no path off the bridge subnet (no internet, no `api.anthropic.com`). ### How the isolated container gets its resolver nixos-container copies the **host's** `/etc/resolv.conf` into the container at every start. The host resolver (for example `127.0.0.53` from systemd-resolved, or a LAN router) is unreachable from a private netns and isn't authoritative for the hive's own zones, so it's replaced with the bridge dnsmasq at boot. Because the copy happens on every start, it would clobber a declarative `environment.etc."resolv.conf"` — so the wiring is runtime: - `hive-priv` drops a marker file (`/etc/hyperhive-bridge-dns`, carrying the gateway IP) into each container's `/etc`. - the `hyperhive-isolated-dns` oneshot (`nix/agent-modules/network.nix`), gated on that marker, rewrites `/etc/resolv.conf` to `nameserver ` at boot. It's ordered `before` the harness (`hive-ag3nt`), the matrix daemon, and the forge-token fetch so the resolver is correct before the first DNS lookup. **Why isolation is safe**: hive-c0re's control-plane sockets are unix domain sockets bind-mounted into containers, not network listeners — see the _Control plane (no network)_ bullet under [Network map](#network-map) above. `PRIVATE_NETWORK=1` has no effect on a path that never touches the network stack. The nix side also enables IP forwarding + NAT (agents reach the internet through the host) and drops bridge-subnet → loopback traffic from its own nftables table (`inet hive_egress`, `nix/host-modules/hive-egress.nix`, which also holds the `bridge hive_egress` table of _Agent bridge source check_; defence-in-depth against a compromised agent reaching the c0re dashboard HTTP at `127.0.0.1`). Agents have no legitimate reason to reach the dashboard over loopback — the hive-c0re admin socket is a UDS, not TCP. ### Agent bridge egress log `services.hyperhive.network.egress.forward` sets what the `forward` chain of the `inet hive_egress` table does with traffic the host routes from the agent bridge to anywhere but the bridge and the `wg-hive` mesh interface. It takes `accept`, `log` (the default) or `drop`. The evaluation refuses `drop` for now: the traffic that squid doesn't handle (the unrestricted agents, the service containers, every port but 80 and 443) has no rule that lets it through yet. In `log` mode the chain blocks nothing. It logs each new flow and counts every packet. - **Which traffic.** IPv4 and IPv6 alike (the table is `inet`). The chain never sees traffic to the host's own addresses, because the host delivers it locally: a connection to squid on `:3128`, to dnsmasq or to the gateway leaves no line. Nor does anything squid or the host opens itself. The web traffic of a `restricted` or `log` agent that the `intercept` chain redirects into squid reaches the host too, so squid's log shows it instead (see _Intercepted web traffic_). - **The log line.** The kernel log carries one line per new flow, with the prefix `hive-egress-would-drop ` followed by the usual netfilter fields (`IN`, `OUT`, `SRC`, `DST`, `PROTO` and the ports). Read them with `journalctl -k -g hive-egress-would-drop`. - **Rate limit.** Each source address gets a burst of 20 lines, then one line a second, and the chain forgets it after a minute without a new flow. A flood from one agent can't hide another's flows, and it adds about 250 bytes of journal a second per source address at most. A flow the per-source limit can't log (the address is over its rate, or the table of addresses is full) gets one line with the prefix `hive-egress-would-drop-unmetered ` instead, from a limit shared by all addresses: 5 lines a second after a burst of 50, about 100 MB of journal a day at most. A flow never gets both lines. The counter in `nft list chain inet hive_egress forward` counts every packet, logged or not. - **Which agent.** `SRC` is the agent's address on the bridge. Containers get theirs from the hive's dnsmasq, which records each lease in `/var/lib/dnsmasq/dnsmasq.leases`, one line per lease: ` `. Look the `SRC` address up in the third column; the hostname names the container. A lease lasts one hour, so look an address up soon after the line appears. - **Trust.** A frame that carries another container's source address never reaches the forward chain while `antiSpoof` is `drop` (see _Agent bridge source check_), so `SRC` names the container that sent the flow. In `log` mode a container can still forge it, so a log from a host that ran in `log` mode during the soak doesn't show who sent a flow. ### Agent bridge source check Every container on the agent bridge is root in its own network namespace and shares one L2 segment with the others, so it can send with another container's MAC or address. `services.hyperhive.network.egress.antiSpoof` sets what the `bridge hive_egress` table (`nix/host-modules/hive-egress.nix`) does about it. It takes `drop` (the default) or `log`. Two tables, not one: the bridge carries traffic between two ports, and the `inet` hooks never see it as coming from a port. Only a `bridge`-family hook at `prerouting` sees which veth a frame came in on, so the source check lives in that table and the host-side filtering stays in `inet hive_egress`. - **What a port may send.** The frame's MAC is the one bound to the port. Then, by protocol: IPv4 from an address leased to that MAC, or DHCP from `0.0.0.0` to `255.255.255.255`; ARP whose sender is the port's MAC and an address leased to it, or an ARP probe from `0.0.0.0`; IPv6 from a link-local address (and from `::` in neighbour solicitations and listener reports, which precede an address). A message to UDP port 67 must carry the port's own MAC as its `chaddr`, so a container can't lease, renew or release an address for another. The table refuses a VLAN tag, and everything else counts as a spoof. - **A port nobody owns sends nothing.** Not even DHCP. A container's port is bound a moment after its veth appears, and the container's DHCP client retries until then. - **Where the bindings come from.** Addresses are dynamic, so the table's sets fill at run time. `hive-priv egress-pin` binds a port to the MAC of the link at the other end of its veth pair, found through the container systemd registers for it. udev starts it for each new `vb-*` port (`hive-egress-pin@.service`), and a timer (`hive-egress-pin.timer`, every 30 seconds) runs it for the ports that still have no binding. The timer reads no container while every port has one. The `hive-egress` unit loads the tables with `hive-priv egress-load`: it looks up the bindings first, while the old tables still filter, and puts them and the leases from dnsmasq's lease file into the same nft transaction as the tables. A start or reload never leaves the bridge with empty sets. If loading the leases fails, the unit logs a warning and loads the tables with the bindings alone. A binding stays with the port until the port goes: root in the container can't move the port to another MAC afterwards (state in `/run/hive-egress-pins`). A port never takes a MAC that a binding already holds, so a newcomer can't evict an established container. If two new ports claim one MAC, neither gets a binding. dnsmasq's `dhcp-script` (`hive-priv egress-lease`) adds each lease as a (MAC, address) pair that times out with the lease. - **The window.** The binding takes the MAC the container's link has when the command first looks, normally within a second of the veth appearing. Until then root in the container could change its own MAC, but in that time only the container's early init runs, which is nix-built, and the agent's code starts later. A container that did change its MAC first gets a binding for that MAC only if nobody holds it; a lease follows the `chaddr` the port may send. A port refused because it claimed a held MAC sends nothing, and the timer binds it once its link has a MAC of its own. - **The log.** A refused frame (all of them with `drop`, the same ones with `log`) gets a kernel log line with the prefix `hive-egress-spoof `, rate limited per port: a burst of 20, then one a second. A frame its port can't log gets a line with the prefix `hive-egress-spoof-unmetered ` instead, from a limit shared by all ports: 5 lines a second after a burst of 50. Read them with `journalctl -k -g hive-egress-spoof`. `IN=` is the port, `vb-` (`vb-h-` for an agent), and `SRC` and `MAC=::` are what the container sent; the port names the sender, because a bound port sends only its own MAC. The counters in `nft list chain bridge hive_egress spoof` count every refused frame. - **Why `drop` is the default.** A container that sends from its leased address and its own MAC is never refused, so `drop` breaks nothing a container does legitimately, and without it the egress log can't tell agents apart. `log` is for a live hive where the table refuses a legitimate container (a binding that failed shows as `hive-egress-pin` errors in the journal and `IN=` lines for that port): the same lines and counters, nothing blocked. - **What it doesn't cover.** A container can still send from any IPv6 link-local address and answer DHCP as a server on its own leased address. Enforcement comes with later changes in the same series: the log only shows what such a change would cut. ## Cross-references - `docs/4-implementation/networking/gateway.md` — vhost map + the gateway's other duties