sardanioss/net

January 4, 2026 · View on GitHub

A fork of golang.org/x/net with HTTP/2 fingerprinting support for evading bot detection systems.

Why This Fork?

Modern anti-bot systems (Akamai, Cloudflare, PerimeterX) fingerprint HTTP/2 connections by analyzing:

SETTINGS frame order and values
WINDOW_UPDATE (connection flow) value
Pseudo-header order (:method, :authority, :scheme, :path)
Header priority in HEADERS frame
PRIORITY frames
HPACK dynamic table indexing behavior

The standard golang.org/x/net/http2 package doesn't allow customizing these values, making Go HTTP clients easily detectable. This fork adds full control over all HTTP/2 fingerprint vectors.

Installation

go get github.com/sardanioss/net

Features

HTTP/2 Transport Configuration

import "github.com/sardanioss/net/http2"

transport := &http2.Transport{
    // Custom SETTINGS frame (order matters!)
    Settings: map[http2.SettingID]uint32{
        http2.SettingHeaderTableSize:   65536,
        http2.SettingEnablePush:        0,
        http2.SettingInitialWindowSize: 6291456,
        http2.SettingMaxHeaderListSize: 262144,
    },
    SettingsOrder: []http2.SettingID{
        http2.SettingHeaderTableSize,
        http2.SettingEnablePush,
        http2.SettingInitialWindowSize,
        http2.SettingMaxHeaderListSize,
    },

    // Custom WINDOW_UPDATE value (Chrome uses 15663105)
    ConnectionFlow: 15663105,

    // Pseudo-header order (Chrome: m,a,s,p)
    PseudoHeaderOrder: []string{":method", ":authority", ":scheme", ":path"},

    // Header priority in HEADERS frame
    HeaderPriority: &http2.PriorityParam{
        Weight:    255,  // 256 in Chrome (0-indexed)
        Exclusive: true,
        StreamDep: 0,
    },

    // Stream priority mode
    StreamPriorityMode: http2.StreamPriorityChrome,

    // Custom User-Agent
    UserAgent: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
}

HPACK Indexing Control

import "github.com/sardanioss/net/http2/hpack"

// Configure via Transport
transport := &http2.Transport{
    HPACKIndexingPolicy: hpack.IndexingChrome,
    HPACKNeverIndex:     []string{"x-request-id"},
    HPACKAlwaysIndex:    []string{"accept"},
}

Available indexing policies:

IndexingDefault - Standard Go behavior
IndexingChrome - Emulates Chrome's indexing decisions
IndexingNever - Never index any headers
IndexingAlways - Always index headers (if they fit)

Per-Request Header Ordering

Use magic keys to override header order per-request:

req.Header[http2.HeaderOrderKey] = []string{"accept", "user-agent", "accept-language"}
req.Header[http2.PHeaderOrderKey] = []string{":method", ":authority", ":scheme", ":path"}

PRIORITY Frames

Send PRIORITY frames after connection preface:

transport := &http2.Transport{
    Priorities: []http2.Priority{
        {StreamID: 3, PriorityParam: http2.PriorityParam{Weight: 200, StreamDep: 0}},
        {StreamID: 5, PriorityParam: http2.PriorityParam{Weight: 100, StreamDep: 3}},
    },
}

Chrome 133 Fingerprint

To match Chrome 133's HTTP/2 fingerprint:

transport := &http2.Transport{
    Settings: map[http2.SettingID]uint32{
        http2.SettingHeaderTableSize:   65536,
        http2.SettingEnablePush:        0,
        http2.SettingInitialWindowSize: 6291456,
        http2.SettingMaxHeaderListSize: 262144,
    },
    SettingsOrder: []http2.SettingID{
        http2.SettingHeaderTableSize,
        http2.SettingEnablePush,
        http2.SettingInitialWindowSize,
        http2.SettingMaxHeaderListSize,
    },
    ConnectionFlow:     15663105,
    PseudoHeaderOrder:  []string{":method", ":authority", ":scheme", ":path"},
    HeaderPriority:     &http2.PriorityParam{Weight: 255, Exclusive: true, StreamDep: 0},
    StreamPriorityMode: http2.StreamPriorityChrome,
    HPACKIndexingPolicy: hpack.IndexingChrome,
}

Target Akamai hash: 52d84b11737d980aef856699f885ca86

API Reference

Transport Fields

Field	Type	Description
`Settings`	`map[SettingID]uint32`	Custom HTTP/2 settings values
`SettingsOrder`	`[]SettingID`	Order to send settings in SETTINGS frame
`ConnectionFlow`	`uint32`	WINDOW_UPDATE value (default: 15663105)
`PseudoHeaderOrder`	`[]string`	Order of pseudo-headers
`HeaderOrder`	`[]string`	Order of regular headers
`HeaderPriority`	`*PriorityParam`	Priority data for HEADERS frame
`Priorities`	`[]Priority`	PRIORITY frames to send
`UserAgent`	`string`	Default User-Agent header
`StreamPriorityMode`	`StreamPriorityMode`	Stream priority calculation mode
`HPACKIndexingPolicy`	`hpack.IndexingPolicy`	HPACK dynamic table indexing
`HPACKNeverIndex`	`[]string`	Headers to never index
`HPACKAlwaysIndex`	`[]string`	Headers to always index

Stream Priority Modes

Mode	Description
`StreamPriorityDefault`	Standard Go behavior
`StreamPriorityChrome`	Chrome's priority tree (exclusive on stream 0, weight 256)
`StreamPriorityFirefox`	Firefox's priority tree
`StreamPriorityCustom`	Use custom `StreamPriorityFunc`

HPACK Indexing Policies

Policy	Description
`IndexingDefault`	Standard Go behavior (index if fits)
`IndexingChrome`	Emulates Chrome's indexing decisions
`IndexingNever`	Never index any headers
`IndexingAlways`	Always index headers

License

BSD 3-Clause License (same as golang.org/x/net)