This software designed to bypass Deep Packet Inspection systems found in many Internet Service Providers which block access to certain websites.

It handles DPI connected using optical splitter or port mirroring (Passive DPI) which do not block any data but just replying faster than requested destination, and Active DPI connected in sequence.

Windows 7, 8, 8.1 and 10 with administrator privileges required.

Download latest version from Releases page and run.

Usage: goodbyedpi.exe [OPTION...]
 -p          block passive DPI
 -r          replace Host with hoSt
 -s          remove space between host header and its value
 -f [value]  set HTTP fragmentation to value
 -e [value]  set HTTPS fragmentation to value
 -a          additional space between Method and Request-URI (enables -s, may break sites)

 -1          -p -r -s -f 2 -e 2 (most compatible mode, default)
 -2          -p -r -s -f 2 -e 40 (better speed yet still compatible)
 -3          -p -r -s -e 40 (even better speed)
 -4          -p -r -s (best speed)

Try to run goodbyedpi.exe -1 -a first. If you can open blocked websites it means your ISP has DPI which can be circumvented. This is the slowest and prone to break websites mode, but suitable for most DPI.

Try -1 to see if it works too.

Then try goodbyedpi.exe -2. It should be faster for HTTPS sites. Mode -3 speed ups HTTP websites.

Use goodbyedpi.exe -4 if it works for your ISP's DPI. This is the fastest mode but not compatible with every DPI.

Most Passive DPI send HTTP 302 Redirect if you try to access blocked website over HTTP and TCP Reset in case of HTTPS, faster than destination website. Packets sent by DPI always have IP Identification field equal to 0x0000 or 0x0001, as seen with Russian providers. These packets, if they redirect you to another website (censorship page), are blocked by GoodbyeDPI.

Active DPI is more tricky to fool. Currently the software uses 4 methods to circumvent Active DPI:

• TCP-level fragmentation for first data packet
• Replacing Host header with hoSt
• Removing space between header name and value in Host header
• Adding additional space between HTTP Method (GET, POST etc) and URI

These methods should not break any website as they're fully compatible with TCP and HTTP standards, yet it's sufficient to prevent DPI data classification and to circumvent censorship. Additional space may break some websites, although it's acceptable by HTTP/1.1 specification (see 19.3 Tolerant Applications).

The program loads WinDivert driver which uses Windows Filtering Platform to set filters and redirect packets to the userspace. It's running as long as console window is visible and terminates when you close the window.

This project can be build using GNU Make and mingw. The only dependency is WinDivert.

To build x86 exe run:

make CPREFIX=i686-w64-mingw32 WINDIVERTHEADERS=/path/to/windivert/include WINDIVERTLIBS=/path/to/windivert/x86

And for x86_64:

make CPREFIX=x86_64-w64-mingw32 WINDIVERTHEADERS=/path/to/windivert/include WINDIVERTLIBS=/path/to/windivert/amd64

One way is using an srvstart program.
Unpack it to goodbyedpi directory and create 3 files:

goodbyedpi.ini

[GoodByeDPI]
startup=goodbyedpi.exe
shutdown_method=winmessage
auto_restart=n

srvinstall.bat

srvstart install GoodByeDPI -c %CD%\goodbyedpi.ini

srvremove.bat

srvstart remove GoodByeDPI

Run these batch files as Administrator to install/remove service.
Open Windows Services panel to run service or make it start automaticaly.

zapret by @bol-van (for Linux).

Thanks @basil00 for WinDivert. That's the main part of this program.

Thanks for every BlockCheck contributor. It would be impossible to understand DPI behaviour without this utility.