A library for forwarding packets.
This library uses Go modules. When running commands like go test in this repository, make sure the GO111MODULE environment variable is set to 'on'. See the go command documentation for more details. If you are running Go 1.13 or later, this should not be necessary as the Go tool will support modules by default.
Tests in this package require root access. The easiest way to test is to compile the tests with go test -c and run the output binary using the sudo command.
Be careful if you choose to run the Go tool with the sudo command (e.g. sudo go test). This can cause issues if the tool attempts to download missing dependencies. Namely, the Go tool may not be able to download anything as Git will likely be using a different SSH keypair (or no keypair at all). Worse, the Go tool may create folders in $GOPATH/pkg/mod/cache owned by the root user. This can disrupt future use of the Go tool, even outside of this repository.
This repository includes a demo client and server in demo/client and demo/server.
The server forwards TCP and UDP packets to hardcoded IP addresses configured with the -tcpdest and -udpdest flags.
The client opens a TUN device.
For example:
sudo iptables -d OUTPUT -p tcp -m conntrack --ctstate ESTABLISHED --ctdir ORIGINAL --tcp-flags RST RST -j DROP
cd demo/server
go build && sudo ./server
cd demo/client
go build && sudo ./client
curl http://10.0.0.1/1GB.zip > /dev/null