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x/crypto/ssh: TCP Forwarding Twice Hangs Second Connection #14598

theonewolf opened this issue Mar 2, 2016 · 1 comment

x/crypto/ssh: TCP Forwarding Twice Hangs Second Connection #14598

theonewolf opened this issue Mar 2, 2016 · 1 comment


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@theonewolf theonewolf commented Mar 2, 2016

Please answer these questions before submitting your issue. Thanks!

  1. What version of Go are you using (go version)?

    > go version
    go version go1.6 linux/amd64
  2. What operating system and processor architecture are you using (go env)?

    Ubuntu 14.04.4 LTS

    > go env
    GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
  3. What did you do?
    (Use to provide a runnable example, if possible.)

    If I use Dial() on an SSH Client more than once, the second returned net.Conn can not read/write until the first Dial completes. The write's appear to work fine on the returned net.Conn, but aren't actually delivered until the first one is Close()d.


            sshClient, err := ssh.Dial("tcp", serverstr, sshConfig)
            remoteConn, err := sshClient.Dial("tcp", remoteString)
            defer remoteConn.Close()
            remoteConn2, err := sshClient.Dial("tcp", remoteString)

    In this code, remoteConn2 will not send bytes until remoteConn is Close()d, and remoteConn2 will not Read() until remoteConn is closed.

  4. What did you expect to see?

    I expect every Dial()ed connection to be independent of the others and able to fully multiplex. I don't want to have to wait for previous Dial()ed connections to close.

    This greatly hinders throughput.

  5. What did you see instead?

    I must Close() previously Dial()ed connections if I want any new ones to work.

@theonewolf theonewolf changed the title x/crypto/ssh: Dialing Twice Hangs Second Connection x/crypto/ssh: TCP Forwarding Twice Hangs Second Connection Mar 2, 2016
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@theonewolf theonewolf commented Mar 2, 2016

This was with a single-threaded dev server, I believe that was the issue. But, the concurrent performance off ssh still seems a bit low.

@theonewolf theonewolf closed this Mar 2, 2016
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