[mythtv-commits] Ticket #10288: FE Won't Connect to BE in 0.25pre if bindv6only = 1

MythTV noreply at mythtv.org
Thu Jan 26 05:00:01 UTC 2012

#10288: FE Won't Connect to BE in 0.25pre if bindv6only = 1
 Reporter:  Bill Meek <keemllib@…>          |           Type:  Patch -
   Status:  new                             |  Feature
Milestone:  unknown                         |       Priority:  minor
  Version:  Master Head                     |      Component:  MythTV -
 Keywords:                                  |  General
                                            |       Severity:  medium
                                            |  Ticket locked:  0
 If a user upgrades to 0.25{pre}, and their distribution sets bindv6only =
 their frontends (combined or remote) will not connect to their backend.

 1st, thanks to Ian Clark (mrrooster) and Erich (mepisrocks) for their help
 in diagnosing this. Their Debian and Mepis systems (respectively) were
 failing and had bindb6only = 1.

 Users can check their system by typing:
 sysctl -a 2>/dev/null | grep bindv6only
 To duplicate:
 On a master backend:
 Run 0.25pre
 Verify that IPv4 addresses are set for the ...ServerIPs
 Add /etc/sysctl.d/mythtv-bind-test.conf
 Put: net.ipv6.bindv6only = 1 in that file
 Start a mythfrontend running

 The FE will get the "Could not connect to the master backend server."
 pop up.

 Solution 1 (probably correct, easily overlooked):

 Users / Distributions should not set bindv6only = 1. Note: #9820, #9840
 and #10165
 as well as posts on the -users list say this is already a problem.

 Most likely solved by searching for bindv6only in files under
 /etc/sysctl.d and
 removing it, commenting it out or setting it to 0.

 Solution 2 (delay the problem):

 Tested under v0.25pre-4146-g633370e.

 The attached patch will prevent binding to IPv6 '''as long as''' the user
 hasn't configured any IPv6 routable addresses on their system.  It does
 this by ignoring Host (::1) and Link Local (fe80::) addresses that are
 automatically configured by the system.

 If/when a user adds a Global IPv6 address, the FE will not connect if
 bindv6only = 1.

 Solution 3 (bindv6only check/error message)

 Included in the patch (in the #ifdef at the end) is a test of the
 bindv6only setting. I used the /proc/sys interface only because in
 the ubuntu man pages it says sysctl(2) may go away.

Ticket URL: <http://code.mythtv.org/trac/ticket/10288>
MythTV <http://code.mythtv.org/trac>
MythTV Media Center

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