a6-plugin-ip-restriction

Overview

The ip-restriction plugin controls access to routes based on client IP address. Configure a whitelist (only listed IPs allowed) or a blacklist (listed IPs blocked). Supports individual IPs and CIDR ranges for both IPv4 and IPv6.

When to Use

• Restrict API access to known IP ranges (office, VPN, partners)
• Block malicious IPs or IP ranges
• Limit admin endpoints to internal networks
• Implement geo-based access control at the IP level

Plugin Configuration Reference (Route/Service)

Field	Type	Required	Default	Description
whitelist	array[string]	Conditional*	—	IPs/CIDR ranges allowed access
blacklist	array[string]	Conditional*	—	IPs/CIDR ranges denied access
message	string	No	"Your IP address is not allowed"	Error message (1–1024 chars)
response_code	integer	No	403	HTTP status on denial (403 or 404)

*Constraint: Exactly one of whitelist or blacklist is required. Cannot use both simultaneously.

How IP Matching Works

• Whitelist: Request allowed only if client IP matches an entry. All others blocked.
• Blacklist: Request blocked if client IP matches an entry. All others allowed.
• CIDR support: Full support for CIDR notation (e.g., 192.168.1.0/24, 10.0.0.0/8, 2001:db8::/32).
• IPv4 and IPv6: Both address families supported.
• Default IP source: Uses $remote_addr (direct client IP from the TCP connection).

Step-by-Step: Whitelist an IP Range

1. Create a route with ip-restriction

a6 route create -f - <<'EOF'
{
  "id": "internal-api",
  "uri": "/admin/*",
  "plugins": {
    "ip-restriction": {
      "whitelist": [
        "10.0.0.0/8",
        "172.16.0.0/12",
        "192.168.0.0/16"
      ]
    }
  },
  "upstream": {
    "type": "roundrobin",
    "nodes": {
      "backend:8080": 1
    }
  }
}
EOF

2. Verify access

# From allowed IP (e.g., 10.0.1.5) → 200 OK
curl -i http://127.0.0.1:9080/admin/dashboard

# From blocked IP → 403 Forbidden
# {"message": "Your IP address is not allowed"}

Step-by-Step: Blacklist Specific IPs

a6 route create -f - <<'EOF'
{
  "id": "public-api",
  "uri": "/api/*",
  "plugins": {
    "ip-restriction": {
      "blacklist": [
        "203.0.113.0/24",
        "198.51.100.42"
      ],
      "message": "Access denied from your network",
      "response_code": 403
    }
  },
  "upstream": {
    "type": "roundrobin",
    "nodes": {
      "backend:8080": 1
    }
  }
}
EOF

Common Patterns

Real client IP behind a proxy (X-Forwarded-For)

By default, ip-restriction uses $remote_addr which is the direct client (often a load balancer). To use the real client IP, combine with the real-ip plugin:

{
  "plugins": {
    "real-ip": {
      "source": "http_x_forwarded_for",
      "trusted_addresses": ["10.0.0.0/8"]
    },
    "ip-restriction": {
      "whitelist": ["203.0.113.0/24"]
    }
  }
}

Critical: Always set trusted_addresses in real-ip to prevent IP spoofing. Only accept X-Forwarded-For from known proxy IPs.

Custom 404 response (hide endpoint existence)

{
  "plugins": {
    "ip-restriction": {
      "blacklist": ["0.0.0.0/0"],
      "whitelist": ["10.0.0.0/8"],
      "response_code": 404,
      "message": "Not found"
    }
  }
}

Note: You cannot actually use both whitelist and blacklist. Use whitelist alone to achieve the same effect — all IPs not in the whitelist are blocked.

IPv6 CIDR ranges

{
  "plugins": {
    "ip-restriction": {
      "whitelist": [
        "2001:db8::/32",
        "::1"
      ]
    }
  }
}

Troubleshooting

Symptom	Cause	Fix
Legitimate users blocked	Using $remote_addr behind proxy	Add real-ip plugin with trusted_addresses
All users blocked on whitelist	Client IPs not in whitelist CIDR	Verify IP ranges with curl ifconfig.me from client
Cannot use both whitelist and blacklist	Schema enforces oneOf	Use whitelist only (blocks all non-listed)
IP restriction not working after change	IP matchers are LRU-cached	Update the route config to bust cache

Config Sync Example

version: "1"
routes:
  - id: internal-api
    uri: /admin/*
    plugins:
      ip-restriction:
        whitelist:
          - "10.0.0.0/8"
          - "172.16.0.0/12"
    upstream_id: admin-upstream
upstreams:
  - id: admin-upstream
    type: roundrobin
    nodes:
      "backend:8080": 1