Question: ```
from fabric.api import env
from fabric.api import run

class FabricSupport:
    def __init__ (self):
        pass

    def run(self, host, command):
        env.key_filename = 'C:/.ssh/dev.pub'
        env.host_string = "%s:%s" % (host, 22)
        run(command, timeout=5)

fab = FabricSupport()

def execute(host, txt):
    stdout = ""
    try:
        stdout = fab.run(host, txt)
    except Exception, e:
        stdout = str(e)
    return stdout

result = execute("23.23.23.23", "uname -a")

```

it just outputs the following and stays like that indefinitely. timeout doesn't seem to be working. It would be great if it was more verbose so I could investigate what is going on.

[12.45.241.11:22] run: uname -a

Answer: 
I encountered the same problem today with an Ubuntu host. My problem was the active shell setting:

`env.shell = /bin/sh -l -c`

With this shell the script would not cleanly execute the remote command and hangup the ssh connection. The control remained inside the ssh shell, causing a timeout in fabric.

With the setting:

`env.shell = "/bin/bash -c"`

everything was OK.

General advice: check the shell and parameters according to your host OS.
I came across the same hanging error this week when I need to run a job taking long time on remote machine.

I resolved it by specifying 'keepalive' option in fabric.api.env config. This config will ask fabric to send keepalive message every a few minutes.

<http://docs.fabfile.org/en/1.14/usage/env.html#keepalive>

I set the value to be 30 and it doesn't hang on a job running for 3 hours.