ipfilterware

Go HTTP middleware to filter clients by IP address.

Rationale

To protect your application open to the internet you might want to allow only verified or well-known IPs. This can be easily done via firewall but sometimes you do not have access to such tools (cloud providers, proxies, serverless, etc). To make this real you can check a connection IP and check it with your config. This library does this.

Features

• Simple API.
• Clean and tested code.
• Thread-safe updates.
• Dependency-free.
• Fetches for popular providers.
  • See fetchers_test.go.

Install

Go version 1.17+

go get github.com/cristalhq/ipfilterware

Example

// your handler or mux/router
var myHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	// do something good
	w.WriteHeader(http.StatusOK)
})

// some IPs to allow (see fetchers_test.go for DNS and proxy helpers)
ips := []string{"10.20.30.40", "100.100.99.1", "42.42.42.42"}

// create ipfilterware handler to pass allowed IPs to myHandler 
handler, err := ipfilterware.New(myHandler, &ipfilterware.Config{
	AllowedIPs: ips,
})
if err != nil {
	panic(err)
}

// use handler as a router or middleware
http.ListenAndServe(":8080", handler)

Documentation

See these docs.

License

MIT License.