Xray-core: Dynamic Chrome User-Agent for all HTTP requests by default (overwriteable through config) by Copilot · Pull Request #5658 · XTLS/Xray-core

Copilot · 2026-02-05T19:25:12Z

功能：为所有 HTTP 请求设置动态 Chrome User-Agent

将 Xray-core 中所有 HTTP 请求的 User-Agent 设为 Chrome 风格，版本号随日期动态变化。

主要改动

新增 common/utils/browser.go

添加 ChromeVersion() 函数计算当前 Chrome 版本号
添加 ChromeUA 变量，启动时初始化一次，供其他包直接使用
策略：
- 仅以 CPU 信息（Family + Model + PhysicalCores + LogicalCores + CacheLine）作为种子初始化伪随机数生成器
- 从 2026.1.13（Chrome 144）开始，每次随机 25-45 天版本 +1
- 一直往上加直到超过当前日期，然后版本 -1

添加 User-Agent 的地方

app/dns/nameserver_doh.go - DoH 客户端
app/observatory/burst/ping.go - Burst Observatory
app/observatory/observer.go - 普通 Observatory
infra/conf/transport_authenticators.go - RAW 的 HTTP 伪装
proxy/http/client.go - HTTP 代理客户端
transport/internet/grpc/dial.go - gRPC
transport/internet/httpupgrade/dialer.go - HTTPUpgrade
transport/internet/reality/reality.go - REALITY 的 SpiderX
transport/internet/splithttp/config.go - XHTTP/SplitHTTP
transport/internet/tls/ech.go - ECH DNS 查询
transport/internet/websocket/config.go - WebSocket

附：uTLS Chrome 指纹使用情况总结

✅ 默认使用 uTLS Chrome 指纹

位置	说明
TCP/gRPC/HTTPUpgrade/SplitHTTP/REALITY/WSS	空 fingerprint 时默认 `HelloChrome_Auto`
TLS ping 命令	硬编码 `HelloChrome_Auto`
ECH DNS 查询	硬编码 `HelloChrome_Auto`
DoH 客户端	硬编码 `HelloChrome_Auto`

❌ 使用 Go 标准 TLS

位置
Observatory (普通和 Burst)

Original prompt

将 Xray-core 里所有 HTTP 请求的 User-Agent 都设为默认 Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36，其中 143 代表 2026 年 1 月，每个月增加 1

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

RPRX · 2026-02-05T19:31:35Z

@copilot XHTTP（SplitHTTP）、gRPC、WebSocket、HTTPUpgrade 被你吃了？？

…date Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

RPRX · 2026-02-05T19:43:06Z

@Fangliding 话说这个为啥是 proxy/http/server.go

Fangliding · 2026-02-05T19:46:54Z

@copilot 把这个功能移到 common/utils 包下面去用 var ChromeUA = getChromeUA() 初始化一个导出的字符串其他包直接用这个字符串就行省去每次计算

Fangliding · 2026-02-05T19:48:17Z

@Fangliding 话说这个为啥是 proxy/http/server.go

plain http的正常处理流程它要把收到的 plain http 请求头稍作修改传出去其实这里不该改的原样转发就好是空就空着

RPRX · 2026-02-05T19:50:07Z

@Fangliding 还有它对于 observatory 只改了 burst，普通的需要改吗还是说代码复用了

Fangliding · 2026-02-05T19:55:46Z

它用了个.get 估计bot用grep找的关键字没看到等它弄完我改改吧就三行

RPRX · 2026-02-05T20:00:07Z

~~没事先让它改改看看，这么说的话 observatory TLS 似乎是没用 Chrome 指纹~~

@copilot 撤回 proxy/http/server.go 的修改，而应当修改 HTTP proxy 的 client

除了 burst 外还要修改普通 observatory 的 UA，另外把两个 observatory 的 TLS 指纹都改为 uTLS Chrome

…de/gRPC, revert proxy/http Co-authored-by: Fangliding <63339210+Fangliding@users.noreply.github.com>

Copilot · 2026-02-05T20:01:52Z

@copilot XHTTP（SplitHTTP）、gRPC、WebSocket、HTTPUpgrade 被你吃了？？

Added User-Agent support for XHTTP (SplitHTTP), gRPC, WebSocket, and HTTPUpgrade in commit a7c0037.

@copilot 把这个功能移到 common/utils 包下面去用 var ChromeUA = getChromeUA() 初始化一个导出的字符串其他包直接用这个字符串就行省去每次计算

Moved to common/utils/browser.go with var ChromeUA = ... that's initialized once at startup. Commit a7c0037.

Co-authored-by: Fangliding <63339210+Fangliding@users.noreply.github.com>

RPRX · 2026-02-05T20:09:28Z

@copilot 顺便把你那 browserVersion() 改成 ChromeVersion()

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot · 2026-02-05T20:10:09Z

~~没事先让它改改看看，这么说的话 observatory TLS 似乎是没用 Chrome 指纹~~

@copilot 撤回 proxy/http/server.go 的修改，而应当修改 HTTP proxy 的 client
...

Added User-Agent to HTTP proxy client and regular observatory in commit 0bb8481.

Regarding TLS fingerprint: Observatory connections go through the outbound handler via tagged.Dialer, so TLS fingerprint is determined by outbound configuration. Adding Chrome fingerprint directly to observatory would require significant changes to how probes work. Could you clarify if this is the desired approach, or should the TLS be configured at the outbound level?

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot · 2026-02-05T20:11:57Z

@copilot 顺便把你那 browserVersion() 改成 ChromeVersion()

Renamed browserVersion() to ChromeVersion() in commit e3fb267.

RPRX · 2026-02-06T00:11:31Z

@copilot 不要以月计算了，Chrome 144 的发布日期为 2026.1.13，假设此后每 45 天发布一个新版本，用户升级周期也是

~~因为看了下 Chrome 有可能有个月不发版本，可以落后点但不能出现未发布的版本~~

… (2026.1.13) Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot · 2026-02-06T00:14:06Z

@copilot 不要以月计算了，Chrome 144 的发布日期为 2026.1.13，假设此后每 45 天发布一个新版本，用户升级周期也是

~~因为看了下 Chrome 有可能有个月不发��...

已修改为 45 天周期：Chrome 144 发布日期为 2026.1.13，此后每 45 天发布新版本，用户升级周期也是 1-45 天。Commit be9e60a。

RPRX · 2026-02-06T00:15:48Z

~~只剩个小特征是在 CDN 看来每 45 天后才会开始出现新版本~~

RPRX · 2026-02-06T00:43:02Z

@copilot 再次推倒重来，使用新策略，往上加：

仅以尽可能多的 CPU 信息作为 seed，弄个伪随机数生成器
每次随机 25-45 天版本 +1，从 2026.1.13 开始一直往上加，直到超过当前日期，然后版本 -1

~~解决了升级 Xray 的问题和固定 45 天的问题，虽然时间长了 avg=35 不过短期内还好，每年修正一下就行~~

…s from 2026.1.13 Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot · 2026-02-06T00:45:52Z

@copilot 再次推倒重来，使用新策略，往上加：

仅以尽可能多的 CPU 信息作为 seed，弄个伪随机数生成器
...

已实现新策略：仅以 CPU 信息作为种子初始化 PRNG，从 2026.1.13 开始每次随机 25-45 天版本 +1，直到超过当前日期后返回版本 -1。Commit 1427b20。

RPRX · 2026-02-06T00:54:24Z

~~取消了用户升级周期是因为重启 Xray 就视为重启 Chrome 就视为升级，毕竟自动更新~~

~~又有个小问题是 CPU 这些参数仅相加感觉随机性不够，for hash 可能更好，不过若真基于独一无二的指纹可能暴露 CPU 信息~~

~~先这样吧，毕竟 Xray 不一定天天重启，也没有 CDN 会闲到搞出类似彩虹表的东西来匹配这个“随机性不够”吧，毕竟不够精确~~

RPRX · 2026-02-06T01:14:40Z

~~如果有人随机到 25 那快炸了，不过想了下有极少数人更新到 Canary 也不是不合理，就这样吧打算合了~~

RPRX · 2026-02-06T01:30:49Z

#4516 (comment) https://developers.google.com/speed/public-dns/docs/doh?hl=zh-cn 提到了 DoH 发 UA 不妥不过 Xray 以前发的也是 Golang，既然不是禁止就发吧，又没真的泄露 UA 毕竟是假的，兼容性可能强一些（（自建）DoH behind CDN）

… (overwriteable through config) (#5658) #4996 (comment) #5658 (comment) --------- Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com> Co-authored-by: Fangliding <63339210+Fangliding@users.noreply.github.com>

paqx · 2026-02-06T08:10:50Z

Simply specify an array and roll it. The user agent
(UA) information is too limited, just a few numbers. It's better to use this to track unusually high-frequency requests, including headers/query strings where each request has a key-value pair but the value is constantly changing.

If we use a roll, it becomes completely random again. Let's stick with CPU-only.

If a CDN were to block XHTTP, it would definitely require multiple dimensions; here, we'll focus on addressing the user agent (UA) characteristics.~~Leave the rest to@paqxAlthough Russia doesn't seem to be Chrome~~

A popular Russian browser is called Yandex Browser. @hxehex created a TLS fingerprint for Yandex Browser (refraction-networking/utls#380). I helped improve and test it. However, my tests show that Yandex Browser has the same fingerprint as Google Chrome, which makes sense because Yandex Browser is based on the same engine.

RPRX · 2026-02-06T08:20:32Z

@paqx TLS 指纹一样是正常的，不过 HTTP UA 呢？比如 Edge 在 Chrome 的基础上加了 Edge 字样

RPRX · 2026-02-06T08:21:49Z

@paqx Chrome 浏览器在俄罗斯的市占率如何，~~不会特别小众吧~~

RPRX · 2026-02-06T08:31:08Z

~~@Fangliding 这个 AI 生成的 Co-authored-by 是 63339210+Fangliding 和我的数字一样，我就说咋怪怪的~~

paqx · 2026-02-06T08:31:10Z

@paqxTLS fingerprinting works fine, but what about HTTP User Agent (UA)? For example, Edge adds the "Edge" name to Chrome's interface.

Sorry. I confused a TLS fingerprint and user-agent header.

No, Google Chrome is quite popular. According to Yandex (https://radar.yandex.ru/browsers), it has a 31% market share in Russia. Yandex Browser has a 38% market share.

However, there's a chance that the government might try to gradually push everyone toward using Yandex Browser, so the Yandex Browser user agent is a better option in Russia.

Examples:
https://useragents.io/explore/browsers/types/browser/maker/yandex-llc-0b6

RPRX · 2026-02-06T08:34:41Z

~~那就还是默认 Chrome 吧，好在 XHTTP 可以通过 extra 分享 UA，有需要的话可以自己改~~

RememberOurPromise · 2026-02-06T11:07:04Z

伊朗的cloudflare流量90%以上被识别为bot，可能就是UA导致的，~~另一说是伊朗政府用bot刷流量制造假象，不过我觉得不是~~

如果Xray指定UA而SB和其他代理客户端没有，可能导致从Bot流量占比的变化推断Xray新客户端的占比
~~不过这可能不是问题，顺便进行市占率统计？~~

RPRX · 2026-02-06T11:12:28Z

~~这还用统计？国外的客户端市占率大概 Xray-core 70%，sing-box 20%，mihomo 0%，服务端市占率大概 Xray-core 90%~~

RPRX · 2026-02-06T11:15:56Z

~~另外伊朗正处于特殊时期连 Xray 都少了很多，他们正流行频繁更换不同的极小众翻墙软件，特征是很明显的所以也就活一周~~

Initial plan

a11b756

Copilot AI assigned Copilot and RPRX Feb 5, 2026

Copilot started work on behalf of RPRX February 5, 2026 19:25 View session

Copilot AI and others added 2 commits February 5, 2026 19:33

feat: set default User-Agent to Chrome with dynamic version based on …

06fd58d

…date Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

fix: add minimum version constraint for ChromeUA and improve test

b61d737

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

RPRX mentioned this pull request Feb 5, 2026

Update grpc.md XTLS/Xray-docs-next#815

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Copilot AI changed the title ~~[WIP] Set default User-Agent for all HTTP requests in Xray-core~~ feat: dynamic Chrome User-Agent for all HTTP requests Feb 5, 2026

Copilot AI requested a review from RPRX February 5, 2026 19:50

Copilot finished work on behalf of RPRX February 5, 2026 19:50

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refactor: move ChromeUA to utils as var, add UA to XHTTP/WS/HTTPUpgra…

a7c0037

…de/gRPC, revert proxy/http Co-authored-by: Fangliding <63339210+Fangliding@users.noreply.github.com>

fix: apply gofmt and remove redundant check in grpc dial

f0021d6

Co-authored-by: Fangliding <63339210+Fangliding@users.noreply.github.com>

Copilot finished work on behalf of RPRX February 5, 2026 20:05

Copilot started work on behalf of RPRX February 5, 2026 20:06 View session

feat: add User-Agent to HTTP proxy client and regular observatory

0bb8481

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot finished work on behalf of RPRX February 5, 2026 20:10

Copilot started work on behalf of RPRX February 5, 2026 20:11 View session

refactor: rename browserVersion() to ChromeVersion()

e3fb267

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot finished work on behalf of RPRX February 6, 2026 00:00

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feat: change to 45-day release cycle based on Chrome 144 release date…

be9e60a

… (2026.1.13) Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot finished work on behalf of RPRX February 6, 2026 00:14

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feat: new strategy with PRNG seeded by CPU, random 25-45 day interval…

1427b20

…s from 2026.1.13 Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>

Copilot finished work on behalf of RPRX February 6, 2026 00:46

RPRX marked this pull request as ready for review February 6, 2026 01:16

RPRX changed the title ~~feat: dynamic Chrome User-Agent for all HTTP requests~~ Xray-core: Dynamic Chrome User-Agent for all HTTP requests by default (overwriteable) Feb 6, 2026

RPRX changed the title ~~Xray-core: Dynamic Chrome User-Agent for all HTTP requests by default (overwriteable)~~ Xray-core: Dynamic Chrome User-Agent for all HTTP requests by default (overwriteable through config) Feb 6, 2026

RPRX merged commit 1f8515e into main Feb 6, 2026

BrewTestBot mentioned this pull request Feb 6, 2026

xray 26.2.6 Homebrew/homebrew-core#266161

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功能：为所有 HTTP 请求设置动态 Chrome User-Agent

主要改动

附：uTLS Chrome 指纹使用情况总结

✅ 默认使用 uTLS Chrome 指纹

❌ 使用 Go 标准 TLS

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