Package Exports

request-filtering-agent
request-filtering-agent/lib/request-filtering-agent.js

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Readme

request-filtering-agent

An http(s).Agent class block the request to Private IP addresses and Reserved IP addresses.

It helps to prevent server-side request forgery (SSRF) attack.

What is SSRF (Server-side request forgery)? Tutorial & Examples

This library depended on ipaddr.js definitions. This library block the request to these IP addresses by default.

So, This library block the request to non-unicast IP addresses.

⚠️ Node.js's built-in fetch does not support http.Agent.

Passing a custom agent to fetch() · Issue #1489 · nodejs/undici

Support `http.Agent` libraries

This library provides Node.js's http.Agent implementation. http.Agent is supported by popular library.

Node.js's built-in http and https
node-fetch
Request
- 📝 request's agent may be insecure
- CVE-2023-28155 Request allows a bypass of SSRF mitigations via an attacker-controller server that does a cross-protocol redirect · Issue #3442 · request/request
- Server-Side Request Forgery in Request · CVE-2023-28155 · GitHub Advisory Database
node-http-proxy
axios
got

request-filtering-agent works with these libraries!

Install

Install with npm:

npm install request-filtering-agent

Usage

useAgent(url, options) return an agent for the url.

The agent blocks the request to Private network and Reserved IP addresses by default.

const fetch = require("node-fetch");
const { useAgent } = require("request-filtering-agent");
const url = 'http://127.0.0.1:8080/';
fetch(url, {
    // use http or https agent for url
    agent: useAgent(url, { stopPortScanningByUrlRedirection: true })
}).catch(err => {
    console.err(err); // DNS lookup 127.0.0.1(family:4, host:127.0.0.1.nip.io) is not allowed. Because, It is private IP address.
});

request-filtering-agent support loopback domain like nip.io. This library detects the IP address that is dns lookup-ed.

$ dig 127.0.0.1.nip.io

;127.0.0.1.nip.io.		IN	A

;; ANSWER SECTION:
127.0.0.1.nip.io.	300	IN	A	127.0.0.1

Example code:

const fetch = require("node-fetch");
const { useAgent } = require("request-filtering-agent");
const url = 'http://127.0.0.1.nip.io:8080/';
fetch(url, {
    agent: useAgent(url)
}).catch(err => {
    console.err(err); // DNS lookup 127.0.0.1(family:4, host:127.0.0.1.nip.io) is not allowed. Because, It is private IP address.
});

It will prevent DNS rebinding

API

export interface RequestFilteringAgentOptions {
    // Allow to connect private IP address
    // This includes Private IP addresses and Reserved IP addresses.
    // https://en.wikipedia.org/wiki/Private_network
    // https://en.wikipedia.org/wiki/Reserved_IP_addresses
    // Example, http://127.0.0.1/, http://localhost/, https://169.254.169.254/
    // Default: false
    allowPrivateIPAddress?: boolean;
    // Allow to connect meta address 0.0.0.0
    // 0.0.0.0 (IPv4) and :: (IPv6) a meta address that routing another address
    // https://en.wikipedia.org/wiki/Reserved_IP_addresses
    // https://tools.ietf.org/html/rfc6890
    // Default: false
    allowMetaIPAddress?: boolean;
    // Allow address list
    // This values are preferred than denyAddressList
    // Default: []
    allowIPAddressList?: string[];
    // Deny address list
    // Default: []
    denyIPAddressList?: string[]
    // prevent url redirection attack
    // connection not made to private IP adresses where the port is closed
    // Default: false
    stopPortScanningByUrlRedirection?: boolean;
}
/**
 * Apply request filter to http(s).Agent instance
 */
export declare function applyRequestFilter<T extends http.Agent | https.Agent>(agent: T, options?: RequestFilteringAgentOptions): T;
/**
 * A subclass of http.Agent with request filtering
 */
export declare class RequestFilteringHttpAgent extends http.Agent {
    constructor(options?: http.AgentOptions & RequestFilteringAgentOptions);
}
/**
 * A subclass of https.Agent with request filtering
 */
export declare class RequestFilteringHttpsAgent extends https.Agent {
    constructor(options?: https.AgentOptions & RequestFilteringAgentOptions);
}
export declare const globalHttpAgent: RequestFilteringHttpAgent;
export declare const globalHttpsAgent: RequestFilteringHttpsAgent;
/**
 * Get an agent for the url
 * return http or https agent
 * @param url
 */
export declare const useAgent: (url: string, options?: https.AgentOptions & RequestFilteringAgentOptions) => RequestFilteringHttpAgent | RequestFilteringHttpsAgent;

Example: Create an Agent with options

An agent that allow requesting 127.0.0.1, but it disallows other Private IP.

const fetch = require("node-fetch");
const { RequestFilteringHttpAgent } = require("request-filtering-agent");

// Create http agent that allow 127.0.0.1, but it disallow other private ip
const agent = new RequestFilteringHttpAgent({
    allowIPAddressList: ["127.0.0.1"], // it is preferred than allowPrivateIPAddress option
    allowPrivateIPAddress: false, // Default: false
});
// 127.0.0.1 is private ip address, but it is allowed
const url = 'http://127.0.0.1:8080/';
fetch(url, {
    agent: agent
}).then(res => {
    console.log(res); // OK
});

Example: Apply request filtering to excising `http.Agent`

You can apply request filtering to http.Agent or https.Agent using applyRequestFilter method.

const http = require("http")
const fetch = require("node-fetch");
const { applyRequestFilter } = require("request-filtering-agent");

// Create http agent with keepAlive option
const agent = new http.Agent({
    keepAlive: true,
});
// Apply request filtering to http.Agent
const agentWithFiltering = applyRequestFilter(agent, {
    allowPrivateIPAddress: false // Default: false
});
// 169.254.169.254 is private ip address aka. link-local addresses
// https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html
// https://serverfault.com/questions/427018/what-is-this-ip-address-169-254-169-254
const url = 'http://169.254.169.254/';
fetch(url, {
    agent: agentWithFiltering
}).catch(error => {
    console.error(error); // Dis-allowed
});

welefen/ssrf-agent: make http(s) request to prevent SSRF
- It provides only high level wrapper
- It only handles Private IP address that is definition in node-ip
  - Missing Meta IP Address like 0.0.0.0

Changelog

See Releases page.

Running tests

Install devDependencies and Run yarn test:

yarn test

📝 This testing require IPv6 supports:

Travis CI: NG
GitHub Actions: OK

Contributing

Pull requests and stars are always welcome.

For bugs and feature requests, please create an issue.

For security issue, please see SECURITY.md

Fork it!
Create your feature branch: git checkout -b my-new-feature
Commit your changes: git commit -am 'Add some feature'
Push to the branch: git push origin my-new-feature
Submit a pull request :D

JSPM