How to connect remote ssh server with socks proxy?

Question

package main

import (
    "errors"
    "fmt"
    "net"

    "golang.org/x/crypto/ssh"
)

var (
    socks    string = "127.0.0.1:8000"
    server   string = "192.168.1.1:2222"
    cmd      string = ""
    login    string = "root"
    password string = ""
)

func main() {
    c, err := netConn(socks)
    if err != nil {
        fmt.Println(err)
    }
    conf := &ssh.ClientConfig{
        User: login,
        Auth: []ssh.AuthMethod{
            ssh.Password(password),
        },
    }
    client, err := Dialer(conf, c, server)
    if err != nil {
        fmt.Println(err)
    }
    session, err := client.NewSession()
    defer session.Close()
    if err != nil {
        fmt.Println(err)
    }
    session.Run(cmd)
}

func netConn(addr string) (net.Conn, error) {
    conn, err := net.Dial("tcp", addr)
    if err != nil {
        return nil, errors.New(fmt.Sprintf("Unable to connect to %v", err))
    }
    return conn, nil
}

func Dialer(conf *ssh.ClientConfig, c net.Conn, host string) (*ssh.Client, error) {
    conn, chans, reqs, err := ssh.NewClientConn(c, host, conf)
    if err != nil {
        return nil, err
    }
    return ssh.NewClient(conn, chans, reqs), nil
}

Client panic

ssh: handshake failed: EOF

panic: runtime error: invalid memory address or nil pointer dereference

[signal 0xb code=0x1 addr=0x0 pc=0x80f3e2d]

goroutine 1 [running]:

panic(0x8201b60, 0x18522030)

/usr/lib/go/src/runtime/panic.go:464 +0x326

golang.org/x/crypto/ssh.(*Client).NewSession(0x0, 0x1, 0x0, 0x0)

/home/user/go/src/golang.org/x/crypto/ssh/client.go:129 +0xcd

main.main()

/home/user/go/src/ss/i.go:34 +0x276

And socks server in log

[ERR] socks: Unsupported SOCKS version: [83]

How i can make it posible? Thanks.

danmux danmux · Accepted Answer · 2018-01-15T15:55:17

You can use the x/net/proxy package as follows:

package main

import (
    "log"

    "golang.org/x/crypto/ssh"
    "golang.org/x/net/proxy"
)

func main() {

    sshConfig := &ssh.ClientConfig{
        User: "user",
        // Auth: .... fill out with keys etc as normal
    }

    client, err := proxiedSSHClient("127.0.0.1:8000", "127.0.0.1:22", sshConfig)
    if err != nil {
        log.Fatal(err)
    }

    // get a session etc...
}

func proxiedSSHClient(proxyAddress, sshServerAddress string, sshConfig *ssh.ClientConfig) (*ssh.Client, error) {
    dialer, err := proxy.SOCKS5("tcp", proxyAddress, nil, proxy.Direct)
    if err != nil {
        return nil, err
    }

    conn, err := dialer.Dial("tcp", sshServerAddress)
    if err != nil {
        return nil, err
    }

    c, chans, reqs, err := ssh.NewClientConn(conn, sshServerAddress, sshConfig)
    if err != nil {
        return nil, err
    }

    return ssh.NewClient(c, chans, reqs), nil
}

How to connect remote ssh server with socks proxy?

2 Answers