rawsocket

Rawsocket

Rawsocket is a Golang raw socket implementation for Windows and macOS that mimics the behavior of Linux’s net.IPConn. Due to critical limitations of the official raw socket implementation on Windows and macOS, the standard net.IPConn does not work reliably on those platforms. Rawsocket leverages gopacket to implement functions such as:

• DialIP
• ListenIP
• Read
• ReadFrom
• Write
• WriteTo
• SetReadDeadline
• Close

This unified interface lets you write cross-platform code that handles raw IP packets similarly to how you would on Linux.

Overview

Rawsocket provides a consistent raw IP packet interface across Windows, macOS, and Linux. It abstracts away OS-specific limitations so you can focus on your application logic. On Windows and macOS, rawsocket uses gopacket and requires additional libraries for packet capture and injection.

Requirements

Windows

• Npcap: Install Npcap (ensure it is in "WinPcap API-compatible Mode").
• WinDivert: When compiling the sample client (client.go), download windivert64.sys and windivert.dll and place them in the same directory as the executable. Please note that Rawsocket lib itself does not depend on WinDivert, but in real implementation, you may need it to make your own client application work if you don't want to see a lot of RST packets sending out from client machine.
• Administrator Privileges: Must run as Administrator.

macOS

• libpcap: Install via Homebrew (brew install libpcap) or through other means.
• Administrator Privileges: Elevated privileges may be required.

Linux

• Native raw socket support is available via go standard net lib. Rawsocket just try to extend it to offers a consistent interface on Windows and macos platforms.

Installation

To install Rawsocket, run:

go get github.com/Clouded-Sabre/rawsocket

Make sure you have gopacket installed as well.

Sample Code

The repository includes two sample programs:

• client.go: Sample client using rawsocket.
• server_win.go: Sample server for Windows using rawsocket.

Running the Server on Windows

1. Install Npcap on your system.
2. Build the server:

   go build -o server_win.exe server_win.go
   

3. Run server.exe in a Command Prompt with Administrator privileges.

Note:
For TCP, the sample server creates a dummy TCP socket that binds to port 54321 (without accepting connections) so that the kernel knows the port is in use and does not send RST packets when raw TCP packets are exchanged.

Running the Client on Windows

1. Install Npcap on your system.
2. Download WinDivert files (windivert64.sys and windivert.dll) and place them in the same directory as the client executable.
3. Build the client:

   go build -o client.exe client.go
   

4. Run client.exe as Administrator.

Running on macOS

Build and run the code normally using go build (ensuring libpcap is installed). Elevated privileges may be necessary.

Usage

Rawsocket is used in a similar way to Linux’s net.IPConn. For example, on Linux you might write:

listener, err := net.ListenIP("ip4:tcp", &net.IPAddr{IP: net.ParseIP("192.168.1.100")})

With Rawsocket on Windows or macOS:

core := rawsocket.NewRawSocketCore(arpCacheTimeout, arpRequestTimeout, true)
listener, err := core.ListenIP(net.ParseIP("192.168.1.100"), layers.IPProtocolTCP)

The interface supports functions such as DialIP, Read, ReadFrom, Write, WriteTo, and SetReadDeadline for cross-platform raw packet transmission.

Workarounds & Known Issues

TCP RST packets blocking

When running rawsocket client or server app on Windows and macOS, the system’s TCP stack may send RST packets when it receives raw TCP packets on an unbound port.
Workaround:

• for server app, create a dummy tcp server using stardard net.lib which listens at the port but do not accept any connection. This tells the kernel that the port is in use, preventing RST packets.
• for client app, use Windvert (windows) or pf filtering rules(macos) to block outgoing RST packet. Please see sample code for details.

Please note that Rawsocket lib itself does not handle RST blocking becuase it works at IP layer. You will need to handle it in your own client or server application.

Building and Running

Ensure you run with proper privileges:

• Windows: Run executables as Administrator.
• macOS: Use elevated privileges if necessary.

For building the sample client in Windows, ensure the following files are present in the executable’s directory:

• windivert64.sys
• windivert.dll

Contributing

Contributions, bug reports, and feature requests are welcome! Please submit pull requests or open issues on GitHub.

License

This project is licensed under the MIT License.