ssh-copy-id hanging sometimes

Question

This is a "follow up" to my question from last week. Basically I am seeing that some python code that ssh-copy-id using pexpect occasionally hangs.

I thought it might be a pexect problem, but I am not so sure any more after I was able to collect a "stacktrace" from such a hang.
Here you can see some traces from my application; followed by the stack trace after running into the timeout:

2016-07-01 13:23:32 DEBUG           copy command: ssh-copy-id -i /yyy/.ssh/id_rsa.pub someuser@some.ip

2016-07-01 13:23:33 DEBUG           first expect: 1

2016-07-01 13:23:33 DEBUG           sending PASSW0RD

2016-07-01 13:23:33 DEBUG           consuming output from remote side ... 

2016-07-01 13:24:03 INFO            Timeout occured ... stack trace information ...



2016-07-01 13:24:03 INFO            Traceback (most recent call last):





File "/usr/local/lib/python3.5/site-packages/pexpect-3.3-py3.5.egg/pexpect/__init__.py", line 1535, in expect_loop

c = self.read_nonblocking(self.maxread, timeout)

File "/usr/local/lib/python3.5/site-packages/pexpect-3.3-py3.5.egg/pexpect/__init__.py", line 968, in read_nonblocking

raise TIMEOUT('Timeout exceeded.')

pexpect.TIMEOUT: Timeout exceeded.



During handling of the above exception, another exception occurred:

Traceback (most recent call last):

 File "xxx/PrepareSsh.py", line 28, in execute

   self.copy_keys(context, user, timeout)

 File "xxx/PrepareSsh.py", line 83, in copy_keys

   child.expect('[#\$]')

 File "/usr/local/lib/python3.5/site-packages/pexpect-3.3-py3.5.egg/pexpect/__init__.py", line 1451, in expect

timeout, searchwindowsize)

 File "/usr/local/lib/python3.5/site-packages/pexpect-3.3-py3.5.egg/pexpect/__init__.py", line 1466, in expect_list

timeout, searchwindowsize)

 File "/usr/local/lib/python3.5/site-packages/pexpect-3.3-py3.5.egg/pexpect/__init__.py", line 1568, in expect_loop

raise TIMEOUT(str(err) + '\n' + str(self))

pexpect.TIMEOUT: Timeout exceeded.

<pexpect.spawn object at 0x2b74694995c0>

version: 3.3

command: /usr/bin/ssh-copy-id

args: ['/usr/bin/ssh-copy-id', '-i', '/yyy/.ssh/id_rsa.pub', 'someuser@some.ip']

searcher: <pexpect.searcher_re object at 0x2b746ae1c748>

buffer (last 100 chars): b'\r\n/usr/bin/xauth:  creating new authorityy file /home/hmcmanager/.Xauthority\r\n'

before (last 100 chars): b'\r\n/usr/bin/xauth:  creating new authority file /home/hmcmanager/.Xauthority\r\n'

after: <class 'pexpect.TIMEOUT'>

So, what I find kinda strange: xauth showing up in the messages that pexpect received.

You see, today, I created another VM for testing; and did all the setup manually. This is what I see when doing so:

> ssh-copy-id -i ~/.ssh/id_rsa.pub someuser@some.ip



 /usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/xxx/.ssh/id_rsa.pub"

The authenticity of host 'some.ip (some.ip)' can't be established.

ECDSA key fingerprint is SHA256:7...

Are you sure you want to continue connecting (yes/no)? yes

/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed

/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys

someuser@some.ip's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   ....

So, lets recap:

when I run ssh-copy-id manually ... everything works; and the string "xauth" doesn't show up in the output coming back

when I run ssh-copy-id programmatically, it works most of the time; but sometimes there are timeouts ... and that message about xauth is send to my client

This is driving me crazy. Any ideas are welcome.

Answer 1

xauth reference smells like you are requesting X11 Forwarding. It will be configured in your ~/.ssh/config. That might be the difference in your configuration that can cause the hangs.

ssh-copy-id hanging sometimes

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