golang ssh dial timeout

Question

What is the best way to create DialTimeout on ssh connection? For example, this code always returns "Ping deadline exceed":

func (t *Tunnel) ping(sshConn *ssh.Client, addr string) (net.Conn, error) {
    var (
        conn net.Conn
        err  error
        done chan int
    )
    go func() {
        time.Sleep(getSeconds(10))
        err = errors.New("Ping deadline exceed")
        log.Printf("%v\nStatus: bad %s -> %s", err, t.serverAddr, addr)
        t.writeStatus(bad)
        done <- 1
        close(done)
    }()
    go func() {
        conn, err = sshConn.Dial("tcp", addr)
        if err != nil {
            t.writeStatus(bad)
            log.Printf("%v\nStatus: bad %s -> %s", err, t.serverAddr, addr)
        }
        done <- 1
        close(done)
    }()
    <-done
    return conn, err
}

PS Timeout in ssh.ClientConfig is set to 5 seconds

I've set timeout in ssh.ClientConfig, but i still have infinite delay when ssh server is closed. However, I've found a mistake, done chan int needs to be created though make(chan int) — abritov
– abritov, Commented Mar 30, 2017 at 15:22
Sorry, I initially misunderstood your question. There is no way to supply a timeout for an ssh direct-tcpip command, but the remote host should be able to timeout eventually, though probably not in under 10 seconds (depends on the remote hosts kernel TCP settings) — Mr_Pink
– Mr_Pink, Commented Mar 30, 2017 at 15:59

Safak · Accepted Answer · 2020-02-14 11:04:20Z

5

It's been two years but, may someone need the solution. So here it is.

In ssh.Dial, you can give configuration via ssh.ClientConfig,

config := &ssh.ClientConfig { Timeout: time.Minute }
client, _ := ssh.Dial("tcp", t.ServerAddr, config)

You can find more in here:

// A Timeout of zero means no timeout. Timeout time.Duration

answered Feb 14, 2020 at 11:04

Safak

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Comments

Ryan Guest · Accepted Answer · 2017-05-12 06:44:31Z

-1

Instead of using sshConn.Dial take a look at:

func DialTimeout(network, address string, timeout time.Duration) (Conn, error)

From the connection docs:

DialTimeout acts like Dial but takes a timeout. The timeout includes name resolution, if required.

answered May 12, 2017 at 6:44

Ryan Guest

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1 Comment

Berkant İpek Over a year ago

direct-tcpip does not support deadlines. sourcegraph.com/github.com/golang/crypto/-/blob/ssh/….

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