grasshopper

README

grasshopper

The grasshopper will listen for incoming UDP packets and forward them to the configured destination. Optionally, the listener can be configured to apply cryptogrraphy on both the incoming and outgoing packets, with different keys and methods.

Install

go install  github.com/xtaci/grasshopper/cmd/grasshopper@latest     

Example Usage

Step 1: start an UDP echo server with ncat with port 5000

ncat -e /bin/cat -k -u -l 5000

Step 2: Start the Level-2 relayer to ncat echo

./grasshopper start --ci aes --co none -l "127.0.0.1:4001" -n "127.0.0.1:5000
--ci aes means we apply cryptography on incoming packets
--co none means we transfer cleartext to ncat echo server

Step 3: Start the Level-1 relayer to Level-2 relayer, meanwhile encrypt the packet

./grasshopper start --ci none --co aes -l "127.0.0.1:4000" -n "127.0.0.1:4001"
--ci none means we don't apply cryptography on incoming packets
--co aes means we encrypt and relay the encrypted packets to next hop

Step 4: Start a demo client, try to type in something.

ncat -u 127.0.0.1 2132

Documentation

Index

• type BlockCrypt
  • func NewAESBlockCrypt(key []byte) (BlockCrypt, error)
  • func NewBlowfishBlockCrypt(key []byte) (BlockCrypt, error)
  • func NewCast5BlockCrypt(key []byte) (BlockCrypt, error)
  • func NewSM4BlockCrypt(key []byte) (BlockCrypt, error)
  • func NewSalsa20BlockCrypt(key []byte) (BlockCrypt, error)
  • func NewTEABlockCrypt(key []byte) (BlockCrypt, error)
  • func NewTripleDESBlockCrypt(key []byte) (BlockCrypt, error)
  • func NewTwofishBlockCrypt(key []byte) (BlockCrypt, error)
  • func NewXTEABlockCrypt(key []byte) (BlockCrypt, error)
• type Listener
  • func ListenWithOptions(laddr string, target string, sockbuf int, timeout time.Duration, ...) (*Listener, error)
  • func (l *Listener) Close() error
  • func (l *Listener) Start()

Types

type BlockCrypt

type BlockCrypt interface {
	// Encrypt encrypts the whole block in src into dst.
	// Dst and src may point at the same memory.
	Encrypt(dst, src []byte)

	// Decrypt decrypts the whole block in src into dst.
	// Dst and src may point at the same memory.
	Decrypt(dst, src []byte)
}

BlockCrypt defines encryption/decryption methods for a given byte slice. Notes on implementing: the data to be encrypted contains a builtin nonce at the first 16 bytes

func NewAESBlockCrypt

func NewAESBlockCrypt(key []byte) (BlockCrypt, error)

NewAESBlockCrypt https://en.wikipedia.org/wiki/Advanced_Encryption_Standard

func NewBlowfishBlockCrypt

func NewBlowfishBlockCrypt(key []byte) (BlockCrypt, error)

NewBlowfishBlockCrypt https://en.wikipedia.org/wiki/Blowfish_(cipher)

func NewCast5BlockCrypt

func NewCast5BlockCrypt(key []byte) (BlockCrypt, error)

NewCast5BlockCrypt https://en.wikipedia.org/wiki/CAST-128

func NewSM4BlockCrypt

func NewSM4BlockCrypt(key []byte) (BlockCrypt, error)

NewSM4BlockCrypt https://github.com/tjfoc/gmsm/tree/master/sm4

func NewSalsa20BlockCrypt

func NewSalsa20BlockCrypt(key []byte) (BlockCrypt, error)

NewSalsa20BlockCrypt https://en.wikipedia.org/wiki/Salsa20

func NewTEABlockCrypt

func NewTEABlockCrypt(key []byte) (BlockCrypt, error)

NewTEABlockCrypt https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm

func NewTripleDESBlockCrypt

func NewTripleDESBlockCrypt(key []byte) (BlockCrypt, error)

NewTripleDESBlockCrypt https://en.wikipedia.org/wiki/Triple_DES

func NewTwofishBlockCrypt

func NewTwofishBlockCrypt(key []byte) (BlockCrypt, error)

NewTwofishBlockCrypt https://en.wikipedia.org/wiki/Twofish

func NewXTEABlockCrypt

func NewXTEABlockCrypt(key []byte) (BlockCrypt, error)

NewXTEABlockCrypt https://en.wikipedia.org/wiki/XTEA

type Listener

type Listener struct {
	// contains filtered or unexported fields
}

Listener defines a server which will be waiting to accept incoming connections

func ListenWithOptions

func ListenWithOptions(laddr string, target string, sockbuf int, timeout time.Duration, crypterIn BlockCrypt, crypterOut BlockCrypt, logger *log.Logger) (*Listener, error)

func (*Listener) Close

func (l *Listener) Close() error

func (*Listener) Start

func (l *Listener) Start()

Start the listener