http-with-key

README

HTTP tunneling with key file

This example shows how you can create a http.Client that has a transport that uses the SSH tunnel. In this example we show how you can load a key from a file. We assume that you have not encrypted the SSH key file with a password.

Running this code

Generating a key for testing

In order to test this you will want to create an SSH key:

ssh-keygen -t ed25519 -f ./id_ed25519 -N ""

This will produce two files in the current directory.

• id_ed25519 contains the private key, and
• id_ed25519.pub contains the public key.

The -N option specifies that there is no password.

Add public key to authorized_keys

You can then add the public key in id_ed25519.pub to your authorized_keys file on the target host. Don't forget to remove the key from authorized_keys after you perform the test unless you want that key to be there.

Run it

In the example below, replace example.com with the host you want to tunnel through.

go run main.go -key id_ed25519 example.com https://news.ycombinator.com/

Using WithKey instead of WithKeyFile

In some circumstances you might want to provide an SSH key (in PEM format) directly rather than reading it from a file. In that case you can use the WithKey option instead of WithKeyFile.

Generating key in Go

If you want to generate the key in Go rather than using ssh-keygen you can do this like so:

package main

import (
    "crypto/ed25519"
    "crypto/rand"
    "encoding/pem"
    "fmt"
    "os"
    "golang.org/x/crypto/ssh"
)

func main() {
    // Generate ed25519 keypair
    _, priv, _ := ed25519.GenerateKey(rand.Reader)

    // Marshal private key into PEM
    privBytes, _ := ssh.MarshalPrivateKey(priv, "")
    pemBlock := &pem.Block{Type: "OPENSSH PRIVATE KEY", Bytes: privBytes}
    pem.Encode(os.Stdout, pemBlock)

    // Marshal public key
    pub, _ := ssh.NewPublicKey(priv.Public().(ed25519.PublicKey))
    fmt.Printf("%s\n", ssh.MarshalAuthorizedKey(pub))
}

Documentation

Overview

Package main shows how you can use an SSH key rather than SSH Agent.