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15c7d1ccb3
An environment with AF_INET6 sockets but no loopback interface creates
nothing but pain.
If an IPv4 server binds to 0.0.0.0:8080, clients may connect to
0.0.0.0:8080, which automatically picks 127.0.0.1 as a source address.
However, when a server binds to [::]:8080, the absence of ::1 causes
clients to fail with ENETUNREACH.
For a demonstration, run the following in a python shell:
import socket
s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM, 0)
s.bind(("", 0))
print s.getsockname() # Example: ('::', 39079, 0, 0)
s.listen(10)
c = socket.socket(socket.AF_INET6, socket.SOCK_STREAM, 0)
c.connect(s.getsockname())
print c.getsockname(), c.getpeername()
This yields the following error:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.7/socket.py", line 224, in meth
return getattr(self._sock,name)(*args)
socket.error: [Errno 101] Network is unreachable
42 lines
1.9 KiB
Python
42 lines
1.9 KiB
Python
from bootstrapvz.base import Task
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from bootstrapvz.common import phases
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from bootstrapvz.common.tasks import network
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from bootstrapvz.common.tools import log_check_call
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import os.path
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class DisableIPv6(Task):
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description = "Disabling IPv6 support"
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phase = phases.system_modification
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predecessors = [network.ConfigureNetworkIF]
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@classmethod
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def run(cls, info):
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network_configuration_path = os.path.join(info.root, 'etc/sysctl.d/70-disable-ipv6.conf')
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with open(network_configuration_path, 'w') as config_file:
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print >>config_file, "net.ipv6.conf.all.disable_ipv6 = 1"
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print >>config_file, "net.ipv6.conf.lo.disable_ipv6 = 0"
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class InstallHostnameHook(Task):
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description = "Installing hostname hook"
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phase = phases.system_modification
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@classmethod
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def run(cls, info):
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# There's a surprising amount of software out there which doesn't react well to the system
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# hostname being set to a potentially long the fully qualified domain name, including Java 7
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# and lower, quite relevant to a lot of cloud use cases such as Hadoop. Since Google Compute
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# Engine's out-of-the-box domain names are long but predictable based on project name, we
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# install this hook to set the hostname to the short hostname but add a suitable /etc/hosts
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# entry.
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#
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# Since not all operating systems which Google supports on Compute Engine work with the
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# /etc/dhcp/dhclient-exit-hooks.d directory, Google's internally-built packaging uses the
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# consistent install path of /usr/share/google/set-hostname, and OS-specific build steps are
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# used to activate the DHCP hook. In any future Debian-maintained distro-specific packaging,
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# the updated deb could handle installing the below symlink or the script itself into
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# /etc/dhcp/dhclient-exit-hooks.d.
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log_check_call(['chroot', info.root, 'ln', '-s',
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'/usr/share/google/set-hostname',
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'/etc/dhcp/dhclient-exit-hooks.d/set-hostname'])
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