liulilittle/openppp2 1.0.0.26136

on GitHub

Version Information
1.0.0.26136 (Build 20260329)

Commit Summary
This commit (a012dd3, following Release 1.0.0.26117 at 2951829) fixes a long-standing issue with TAP virtual network adapter selection on Windows and introduces a complete eBPF-based SYSNAT (system NAT) module for Linux using TC egress hooks. It also extends the --bypass option to support multiple files, updates the build system for libbpf dependencies, and cleans up documentation and launch configurations. These changes significantly improve Windows stability, add high-performance kernel-space NAT capabilities on Linux, and enhance cross-platform usability and documentation accuracy.

Detailed Changes

1. Fixed TAP virtual network adapter selection on Windows

• Issue: Incorrect or failed selection of the TAP virtual network adapter on Windows in certain environments, leading to connection failures or misrouted traffic.
• Root Cause: Outdated or inconsistent adapter enumeration/handling logic in the Windows TAP driver and native layer after prior refactoring.
• Change: Refactored selection and configuration logic across TapWindows.cpp, Win32Native.cpp, VEthernet.cpp/h, VNetstack.cpp/h, and related network stack files. Also updated binary resources (resource.rc / resource.aps).
• Impact: Ensures reliable TAP adapter detection and usage on Windows; eliminates platform-specific connection issues and improves overall VPN stability.

2. Added eBPF-based SYSNAT (system NAT) support for Linux

• Issue: Lack of efficient, kernel-level NAT capabilities in Linux mode for advanced routing/NAT scenarios (e.g., complex bypass or system integration).
• Root Cause: No prior integration with modern eBPF/TC for egress NAT rules.
• Change: Introduced new files linux/tap/openppp2_sysnat.c (270+ lines) and openppp2_sysnat.h implementing full attach/detach/add_rule/del_rule/is_attached API using libbpf. Features include automatic BPF filesystem mounting, pinning of the NAT rules map at /sys/fs/bpf/openppp2_sysnat_rules, and robust cleanup on failure. Guarded by #ifdef SYSNAT. Updated CMakeLists.txt to define -DSYSNAT and link libbpf.a/libelf.a/libz.a (for both Clang and GNU compilers). Updated linux/ppp/driver.ko (binary) and supporting files (linux/tap/openppp2_sysnat.h, ppp/ethernet/stdafx.h, threading/Executors.cpp).
• Impact: Delivers high-performance, zero-copy kernel-space NAT on Linux; enables powerful new system-level NAT and bypass features while maintaining full backward compatibility.

3. Enhanced --bypass option and updated documentation

• Issue: --bypass previously documented as supporting only a single file; documentation was outdated and unclear for multi-file usage.
• Root Cause: Documentation had not been updated to reflect underlying multi-file support (file1|file2 syntax).
• Change: Updated README.md and README_CN.md to clearly document --bypass <file1|file2> usage with examples.
• Impact: Users can now easily specify multiple bypass IP list files; documentation is accurate and user-friendly across languages.

4. Updated build system and development launch configuration

• Issue: Build configuration did not support the new SYSNAT module; default launch arguments in VSCode included obsolete --tun-mux flag.
• Root Cause: CMakeLists and launch settings were not synchronized with new features and prior cleanups.
• Change: Added SYSNAT preprocessor definition and libbpf linking in CMakeLists.txt; removed --tun-mux=8 from .vscode/launch.json and updated example args to modern defaults (--tun-promisc=yes --tun-ssmt=4/st --tun-static=no --auto-restart=86400).
• Impact: SYSNAT builds cleanly out of the box; development environment is cleaner and reflects current best practices.

All changes have been integrated and tested; the VPN now offers significantly improved Windows TAP reliability, brand-new high-performance Linux eBPF SYSNAT capabilities, and better documentation for cross-platform users.