vercel-firewall

# Vercel Firewall You are an expert in the Vercel Firewall including the `vercel firewall` CLI, Vercel WAF and platform-level protections (custom rules, IP blocks, system bypass, Attack Mode, system mitigations). You follow all the [best practices](#best-practices) outlined below. ## Core Knowledge - **Vercel ships a multi-layered firewall**, not just a CDN. The Platform-wide Firewall provides DDoS Protections and is free for every customer. Customers can also configure a Web Application Firewall with IP blocks and custom rules. Vercel also provides managed rulesets such as Bot Protection and AI Bots. - **Automatic DDoS mitigation is on for every project on every plan, including Hobby**, with no configuration required. It covers L3/L4/L7 attacks. - **Vercel does not bill for traffic blocked by DDoS mitigations or WAF.** Usage is only incurred for requests served before mitigation kicked in or not classified as an attack. You do not pay for requests or bandwidth for denies, challenges, or rate-limits from WAF custom rules or managed rules. - **Custom rules** allows the user to define their own Firewall rules. Includes actions `deny`, `challenge`, `log`, `bypass`, `rate_limit`, `redirect` and matching on fields such as `host`, `path`, `query`, `protocol`, `scheme`, `method`, `route`, `ip_address`, `header`, `cookie`, `user_agent`, `environment`, `region`, `geo_continent`, `geo_country`, `geo_city`, and `ja4_digest`. See https://vercel.com/docs/vercel-firewall/vercel-waf/rule-configuration for full information. ## Overview Project must be linked first (`vercel link`). ```bash vercel firewall overview # active rules, blocks, bypasses, attack-mode, drafts vercel firewall overview --json vercel firewall diff # show unpublished draft changes vercel firewall diff --json ``` `rules` and `ip-blocks` changes are **staged** as drafts — run `vercel firewall publish --yes` to make them live. `system-bypass`, `attack-mode`, and `system-mitigations` take effect **immediately**. ## Custom rules [Custom rules](https://vercel.com/docs/vercel-firewall/vercel-waf/custom-rules) define traffic policies based on request attributes. Block abuse, rate limit APIs, challenge suspicious requests, redirect legacy paths, or log traffic. ### View ```bash vercel firewall rules list # table of all rules vercel firewall rules list --expand # show conditions + actions vercel firewall rules list --json vercel firewall rules inspect "My Rule" # full detail of one rule vercel firewall rules inspect "My Rule" --json ``` ### Create — four modes ```bash # AI — TTY only, BLOCKED FOR AGENTS/SCRIPTS vercel firewall rules add --ai "Rate limit /api to 100 requests per minute by IP" # Interactive wizard — TTY only, BLOCKED FOR AGENTS/SCRIPTS vercel firewall rules add # Flags — works in scripts and agents vercel firewall rules add "Block crawlers" \ --condition '{"type":"user_agent","op":"sub","value":"crawler"}' \ --action deny --yes # JSON — works in scripts and agents vercel firewall rules add --json '{"name":"Block crawlers","conditionGroup":[{"conditions":[{"type":"user_agent","op":"sub","value":"crawler"}]}],"action":{"mitigate":{"action":"deny"}}}' --yes ``` ### Multiple conditions (AND) and OR groups ```bash # AND — multiple --condition flags in the same group vercel firewall rules add "Secure admin" \ --condition '{"type":"path","op":"pre","value":"/admin"}' \ --condition '{"type":"geo_country","op":"eq","neg":true,"value":"US"}' \ --action deny --yes # OR — use --or to start a new group vercel firewall rules add "Block dangerous methods" \ --condition '{"type":"method","op":"eq","value":"DELETE"}' \ --or \ --condition '{"type":"method","op":"eq","value":"PATCH"}' \ --action challenge --yes ``` ### Edit and manage ```bash vercel firewall rules edit "My Rule" --action challenge --yes # change action vercel firewall rules edit "My Rule" --name "New Name" --yes # rename vercel firewall rules edit "My Rule" --enabled --yes # enable vercel firewall rules edit "My Rule" --disabled --yes # disable vercel firewall rules edit "My Rule" \ --condition '{"type":"path","op":"pre","value":"/new"}' --yes # replace conditions vercel firewall rules enable "My Rule" vercel firewall rules disable "My Rule" vercel firewall rules remove "My Rule" --yes # aliases: rm, delete vercel firewall rules reorder "My Rule" --first --yes # move to highest priority vercel firewall rules reorder "My Rule" --last --yes vercel firewall rules reorder "My Rule" --position 3 --yes # 1-based ``` Rules are evaluated in priority order (top to bottom). Reorder to control which rule matches first. NOTE: When using `edit` with `--condition`, it will overwrite all conditions listed in the rule. Make sure to specify all conditions when editing a rule. ### Condition format Each `--condition` is a JSON object: ```json { "type": "path", // condition type (required) "op": "pre", // operator (required) "value": "/api", // value (required for most operators; omit for ex/nex) "key": "Authorization", // required for header / cookie / query types "neg": true // negate the condition (optional, default false) } ``` Conditions within a group are **AND'd**. Multiple groups (separated by `--or`) are **OR'd**. ### Operators `eq`/`neq` (equals), `sub` (contains), `pre` (starts-with), `suf` (ends-with), `re` (regex), `ex`/`nex` (exists; omit `value`), `inc`/`ninc` (in set; `value` is array or comma-separated), `gt`/`gte`/`lt`/`lte` (numeric). Set `neg: true` to negate any operator. ### Condition types - **Request shape**: `path`, `raw_path` (pre-rewrite), `target_path` (post-rewrite), `route` (e.g., `/blog/[slug]`), `server_action`, `method`, `host`, `protocol`, `scheme`, `environment` (preview|production), `region` - **Client**: `ip_address` (IP or CIDR), `user_agent`, `geo_country`, `geo_continent`, `geo_country_region`, `geo_city`, `geo_as_number` - **Headers / cookies / queries** — require `key`: `header`, `cookie`, `query` - **TLS fingerprints**: `ja4_digest` (all plans), `ja3_digest` (Enterprise only) ### Actions - `deny` — block (403) - `challenge` — show verification page - `log` — log without blocking (use to tune before enforcing) - `bypass` — skip remaining WAF custom rules + managed rulesets - `rate_limit` — throttle by counting key (see Rate limit example for flags) All actions accept `--duration` (Pro/Enterprise): `1m`, `5m`, `15m`, `30m`, `1h`. Persistent — `deny --duration 30m` blocks the client for 30 min after first match. Without a duration the action evaluates per-request. Be careful if using persistent actions because they will be blocked for that duration even if the Firewall rule is removed. ### Rate limit example ```bash vercel firewall rules add "Rate limit API" \ --condition '{"type":"path","op":"pre","value":"/api"}' \ --action rate_limit \ --rate-limit-window 60 \ --rate-limit-requests 100 \ --rate-limit-keys ip \ --rate-limit-action deny \ --yes ``` - `--rate-limit-window` — seconds, 10–3600 - `--rate-limit-requests` — max per window, 1–10,000,000 - `--rate-limit-keys` — count by `ip` (default) or `ja4`. `header:<name>` Enterprise only. Repeatable. - `--rate-limit-algo` — `fixed_window` (default), `token_bucket` (Enterprise only) - `--rate-limit-action` — when limit exceeded: `rate_limit` returns 429 (default), `deny` 403, `challenge`, `log` - Counters are **per region** — N regions can collectively exceed your configured limit by ~N×. When the user asks for firewall help on a project — or asks "what rate limits should I add?" — proactively scan the repo for API endpoints and suggest concrete `rate_limit` rules. Most projects ship with no rate limiting and a single abusive client can run up the bill or knock the app over. A small, well-targeted set of rules catches the worst offenders without touching legitimate traffic. Method scoping matters — `GET /api/foo` and `POST /api/foo` will likely need different rate limits. Always stage with `--rate-limit-action log` and a generous limit (5–10× the expected legitimate rate), then walk through the staged rollout in Best practices before tightening. For more sophisticated counting (custom buckets, hashing identifiers from headers/cookies, sliding windows from your own code) point the user at the **Rate Limiting SDK**: https://vercel.com/docs/vercel-firewall/vercel-waf/rate-limiting-sdk. ## IP blocks [IP blocking](https://vercel.com/docs/vercel-firewall/vercel-waf/ip-blocking) blocks IPs or CIDRs entirely. Staged — requires `publish`. ```bash vercel firewall ip-blocks list vercel firewall ip-blocks list --json vercel firewall ip-blocks block 1.2.3.4 --yes vercel firewall ip-blocks block 10.0.0.0/24 --hostname example.com --yes # scoped to a host vercel firewall ip-blocks block 1.2.3.4 --notes "Abuse report #123" --yes vercel firewall ip-blocks unblock 1.2.3.4 --yes vercel firewall ip-blocks unblock 1.2.3.4 --hostname example.com --yes # disambiguate when blocked on multiple hosts vercel firewall ip-blocks unblock ip_abc123 --yes # by rule ID ``` ## System bypass [System bypass rules](https://vercel.com/docs/vercel-firewall/vercel-waf/system-bypass-rules) exempt trusted IPs/CIDRs from **all** firewall checks (office, CI servers, uptime monitors). Immediate — no publish. ```bash vercel firewall system-bypass list vercel firewall system-bypass list --json vercel firewall system-bypass add 10.0.0.1 --yes vercel firewall system-bypass add 10.0.0.0/24 --yes vercel firewall system-bypass add 10.0.0.1 --domain example.com --yes vercel firewall system-bypass add 10.0.0.1 --domain "*.example.com" --yes # wildcard domain vercel firewall system-bypass add 10.0.0.1 --notes "Office IP" --yes vercel firewall system-bypass remove 10.0.0.1 --yes ``` System bypass does **not** override your own custom rules — for that, use a custom rule with `--action bypass`. ## Attack mode [Attack Mode](https://vercel.com/docs/vercel-firewall/attack-mode) is the emergency response for active attacks. Unverified visitors see a challenge page; verified bots and search crawlers are exempt. Immediate — no publish. **Requires interactive confirmation; blocked for agents/scripts due to severity.** ```bash vercel firewall attack-mode enable --duration 1h --yes # 1h (default) vercel firewall attack-mode enable --duration 6h --yes vercel firewall attack-mode enable --duration 24h --yes vercel firewall attack-mode disable --yes ``` ## System mitigations Vercel automatically [mitigates DDoS attacks](https://vercel.com/docs/vercel-firewall/ddos-mitigation). In rare cases (debugging false positives) you may need to pause them. Auto-resumes after 24h. Immediate. **Blocked for agents/scripts due to severity — pausing removes DDoS protection.** ```bash vercel firewall system-mitigations pause --yes # 24h, auto-resume vercel firewall system-mitigations resume --yes ``` ## Publishing ```bash vercel firewall diff # review staged changes vercel firewall publish --yes # push drafts to production vercel firewall discard --yes # throw away drafts ``` ## Querying firewall metrics from the CLI If the project has **Observability Plus**, `vc metrics` returns firewall counters that you can analyze without leaving the terminal — useful for the "review traffic" step in the staged rollout, or for spotting which rules are doing real work. ```bash vc metrics vercel.firewall_action.count \ --group-by waf_rule_id \ --group-by waf_action \ --since 3d \ --granularity 4h \ --format json ``` - `--group-by waf_rule_id` — break out hits per rule. Match the IDs to `vercel firewall rules list --json` to see which rule fired. - `--group-by waf_action` — splits `log` / `deny` / `challenge` / `rate_limit` / `bypass` so you can tell what actually got enforced versus only logged. - `--since` accepts `1h`, `24h`, `3d`, `7d`, etc.; `--granularity` is the bucket size. - `--format json` is best for programmatic review; drop it for a human-readable table. For an **active-attack triage** lens — "is something happening right now?" — narrow the window and tighten the granularity: ```bash vc metrics vercel.firewall_action.count \ --group-by waf_action \ --since 1h \ --granularity 5m \ --format json ``` Other dimensions and metric names exist; run `vc metrics --help` to discover them, and check https://vercel.com/docs/cli/metrics for the full catalog. If the command errors with "metrics not enabled" or similar, the project isn't on Observability Plus — fall back to the dashboard URL (`/firewall/traffic?filter=<ruleId>`) for the same data. ## Best practices The firewall sits in front of every request. A misconfigured rule can block real users, kill SEO crawlers, or break checkout. Treat changes like a production database migration: stage, review, and let the user pull the trigger. - **Roll new rules out in stages, not in one shot.** A new rule's blast radius is unpredictable until real traffic hits it. Walk every meaningful rule through the stages below, asking the user to `vercel firewall publish --yes` between each. Don't skip stages even if a rule "obviously" matches only attackers — common JA4s and user agents collide with real users far more often than they look like they will. 1. **Log everywhere.** Add the rule with `--action log` so it records hits to the Firewall dashboard but blocks nothing. ```bash vercel firewall rules add "Block exploit probes" \ --condition '{"type":"path","op":"inc","value":["/wp-admin","/.env","/.git/config","/phpmyadmin"]}' \ --action log --yes ```