UA3F

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UA3F is an HTTP Header rewriting tool that transparently rewrites HTTP request headers (such as User-Agent) as an HTTP, SOCKS5, TPROXY, REDIRECT, or NFQUEUE server.

Features

• Multiple server modes: HTTP, SOCKS5, TPROXY, REDIRECT, NFQUEUE(UA2F)
• Highly flexible rewriting rule system with multiple rule types and rewriting strategies
• Real-time statistics dashboard with traffic modification monitoring and analysis
• Multiple deployment options: opkg installation, compilation, and Docker deployment
• Compatible with Clash Fake-IP & Redir-Host modes for coexistence
• Supports TTL, TCP Timestamp, TCP Window and IP ID obfuscation
• Supports TCP Desync fragment reordering to evade Deep Packet Inspection (DPI)

Deployment

Three deployment methods are available:

• IPK Package Installation:

  Pre-compiled versions for common architectures are available on the Release page. Download the appropriate version for your device architecture and install it on OpenWrt using opkg install.

• OpenWrt Compilation:

  git clone https://github.com/openwrt/openwrt.git && cd openwrt
  git checkout openwrt-24.10
  ./scripts/feeds update -a && ./scripts/feeds install -a
  git clone https://github.com/SunBK201/UA3F.git package/UA3F
  make menuconfig # Select Network->Web Servers/Proxies->ua3f
  make download -j$(nproc) V=s
  make -j$(nproc) || make -j1 || make -j1 V=sc # make package/UA3F/openwrt/compile -j1 V=sc # Compile single package
  

• Docker Deployment:

  docker run -p 1080:1080 sunbk201/ua3f -f FFF
  

Usage

UA3F supports LuCI Web interface. Navigate to Services -> UA3F for configuration.

For detailed tutorial, please visit: UA3F User Guide

Device and system information regex reference:

(Apple|iPhone|iPad|Macintosh|Mac OS X|Mac|Darwin|Microsoft|Windows|Linux|Android|OpenHarmony|HUAWEI|OPPO|Vivo|XiaoMi|Mobile|Dalvik)

Manual Command Line Launch

opkg install sudo
sudo -u nobody /usr/bin/ua3f

For shellclash/shellcrash users, use the following command:

sudo -u shellclash /usr/bin/ua3f
# If the above command fails, use this one
sudo -u shellcrash /usr/bin/ua3f

Command line parameters:

• -m <mode>: Server mode. Supports HTTP, SOCKS5, TPROXY, REDIRECT. Default: SOCKS5
• -b <bind addr>: Custom bind address. Default: 127.0.0.1
• -p <port>: Port number. Default: 1080
• -l <log level>: Log level. Default: info. Options: debug. Default log location: /var/log/ua3f.log
• -x: Rewrite mode. Supports GLOBAL, DIRECT, RULES. Default: GLOBAL
• -f <UA>: Custom User-Agent. Default: FFF
• -r <regex>: Custom regex to match User-Agent. Default: empty (all User-Agents will be rewritten)
• -s: Partial replacement, only replace the regex matched portion
• -z: Rewrite rules in JSON string format. Only effective in RULES rewrite mode
• -o ttl,tcpts,ipid: Enable TTL, TCP Timestamp, and IP ID obfuscation

Server Mode Description

UA3F supports 5 different server modes, each with unique characteristics:

Server Mode	Working Principle	Clash Dependency	Compatibility	Performance	Coexist with Clash
HTTP	HTTP Proxy	Yes	High	Low	Yes
SOCKS5	SOCKS5 Proxy	Yes	High	Low	Yes
TPROXY	netfilter TPROXY	No	Medium	Medium	Yes
REDIRECT	netfilter REDIRECT	No	Medium	Medium	Yes
NFQUEUE	netfilter NFQUEUE	No	Low	High	Yes

Rewrite Strategy Description

UA3F supports 3 different rewrite strategies:

Rewrite Strategy	Rewrite Behavior	Rewrite Headers	Applicable Modes
GLOBAL	Rewrite all requests	User-Agent	All server modes
DIRECT	No rewriting, pure forwarding	None	All server modes
RULES	Rewrite based on rewriting rules	Customizable	HTTP/SOCKS5/TPROXY/REDIRECT

Clash Configuration

See Clash Configuration

References & Thanks

• UA2F
• uaProxy
• xmurp-ua
• Clash
• mihomo