Difference between revisions of "Enable IPv6"

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(sixxs.net link typo, remove --setloglevel & mention FD01... is OK)
(Enhance optional statement, explain new MBE decision, add -W to netstat, make logging the 1st tool, general cleanup)
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[[Category:HOWTO]]
 
[[Category:HOWTO]]
0.25pre {{gitcommit|37385ba}} allows users the '''option''' of connecting  
+
{{Note box|0.25 allows users the '''option''' of connecting  
to <code>mythbackend</code> via IPv6 for file transfers.
+
to <code>mythbackend</code> via IPv6.
 +
To be clear, enabling IPv6 isn't required for successful
 +
operation of MythTV.
 +
}}
  
This Wiki shows how to activate IPv6. This is
+
This Wiki shows how to activate IPv6. It is
part of a significant change in the way MythTV binds to sockets.
+
part of significant changes in the way
 +
MythTV binds to sockets which should be
 +
transparent to users.
  
 
==IPv6 Configuration==
 
==IPv6 Configuration==
Line 12: Line 17:
  
 
If IPv6 is known to be working, just complete the following.
 
If IPv6 is known to be working, just complete the following.
Otherwise, see [[#Prerequsites]].
+
Otherwise, see [[#Basics]].
  
 
Stop all frontends and backends.
 
Stop all frontends and backends.
  
Using <code>mythtv-setup</code> on the master backend, go to the General page, enter the
+
Using <code>mythtv-setup</code> on the master backend, go to the General page and enter the
address of choice in the <code>IPv6 address:</code> field.
+
address of choice.
 +
 
 +
The configuration of someone who just upgraded to 0.25 will look like this:
  
The field should look something like this.
 
 
<pre>
 
<pre>
IPv6 address: fd01:a:b:1::123
+
Local Backend
 +
    IP address:  192.168.1.123
 +
    IPv6 address: ::1
 +
 
 +
Master Backend
 +
    IP address: 192.168.1.123
 
</pre>
 
</pre>
  
Note that some (non MythTV) programs require their IPv6
+
Change it to look like this:
 +
 
 +
<pre>
 +
Local Backend
 +
    IP address:  192.168.1.123
 +
    IPv6 address: fd01:a:b:1::123
 +
 
 +
Master Backend
 +
    IP address: fd01:a:b:1::123
 +
</pre>
 +
 
 +
The existing IPv4 address shouldn't be changed/removed, as some services
 +
still require it.
 +
 
 +
The pre 0.25 convention that requires both Local Backend and Master Backend addresses
 +
to be the same in order for a backend to be considered a master backend still applies.
 +
It has been expanded to allow for the Master Backend address to equal either the
 +
Local IPv4 '''or''' IPv6 Backend address.
 +
 
 +
Some (non MythTV) programs require their IPv6
 
addresses enclosed in brackets (<code>[]</code>) or the
 
addresses enclosed in brackets (<code>[]</code>) or the
 
addition of a trailing percent sign and Zone Index
 
addition of a trailing percent sign and Zone Index
Line 33: Line 63:
 
backends with their own IPv6 addresses.
 
backends with their own IPv6 addresses.
  
Restart the backend(s). Frontends will now perform file transfers
+
Restart the backend(s).
(e.g. recording playback) via IPv6.
+
  
 
==Which IPv6 address should be used?==
 
==Which IPv6 address should be used?==
Line 43: Line 72:
  
 
Note that even though ULAs are global addresses, no self
 
Note that even though ULAs are global addresses, no self
respecting router will pass them out on the internet.
+
respecting router will pass them out on the internet,
 +
much like IPv4 Private Network addresses (e.g. 192.168.1.123.)
  
 
Use a search engine and look for: 'Unique Local Address generator'
 
Use a search engine and look for: 'Unique Local Address generator'
to find a site that will create ULAs correctly
+
to find a site that will create ULAs correctly like
([http://www.sixxs.net/tools/grh/ula/ for example].)
+
[http://www.sixxs.net/tools/grh/ula/ this], for example.
  
 
For details on constructing ULAs see
 
For details on constructing ULAs see
Line 59: Line 89:
 
Site Local (<code>fec0::/10</code>) addresses were deprecated in 2004.
 
Site Local (<code>fec0::/10</code>) addresses were deprecated in 2004.
  
Host (::1) addresses are configured in MythTV automatically, but
+
Host (::1) addresses are only useful for a stand alone system.
are not routable, use them for a stand alone system.
+
  
 
Since all Link Local addresses have the same prefix
 
Since all Link Local addresses have the same prefix
Line 69: Line 98:
  
 
To list currently assigned IPv6 addresses, type:
 
To list currently assigned IPv6 addresses, type:
<code>ifconfig ethX | grep inet6</code>
+
<code>ifconfig | grep inet6</code>
 
<pre>
 
<pre>
 +
inet6 addr: ::1/128 Scope:Host
 
inet6 addr: fe80::222:22ff:fe22:2222/64 Scope:Link
 
inet6 addr: fe80::222:22ff:fe22:2222/64 Scope:Link
 
inet6 addr: fd01:a:b:1::123/64 Scope:Global
 
inet6 addr: fd01:a:b:1::123/64 Scope:Global
Line 76: Line 106:
 
</pre>
 
</pre>
  
In the above, the middle address is probably the best choice.
+
In the above, the 3rd address is probably the best choice.
 
It is also probably one that must be assigned manually.
 
It is also probably one that must be assigned manually.
  
Line 93: Line 123:
 
Back to [[#IPv6 Configuration]]
 
Back to [[#IPv6 Configuration]]
  
==Prerequsites==
+
==Basics==
  
 
Verify that IPv6 is active on each MythTV host.
 
Verify that IPv6 is active on each MythTV host.
Line 128: Line 158:
 
*Be sure any firewalls have been adjusted to accept the IPv6 addresses being used.
 
*Be sure any firewalls have been adjusted to accept the IPv6 addresses being used.
  
 +
<!--
 
*MySQL connections are currently selected by the hostname information in config.xml and mysql.txt files. Unless a version of MySQL that supports IPv6 is being used, no changes are required.
 
*MySQL connections are currently selected by the hostname information in config.xml and mysql.txt files. Unless a version of MySQL that supports IPv6 is being used, no changes are required.
  
 
*If there are entries in <code>/etc/hosts</code> (etc.), for both IPv4 and IPv6 addresses that have the same hostname (which is perfectly legal,) make sure the host's preferences pick IPv4 first. <code>/etc/gai.conf</code> may exist and control this.
 
*If there are entries in <code>/etc/hosts</code> (etc.), for both IPv4 and IPv6 addresses that have the same hostname (which is perfectly legal,) make sure the host's preferences pick IPv4 first. <code>/etc/gai.conf</code> may exist and control this.
 +
-->
 +
*If the MythTV configuration is correct, but no IPv6 traffic is seen during, for example recording playback, Master Backend Override may be enabled in <code>mythtv-setup</code> General section and the Master Backend IP address is still set to an IPv4 address.
  
 
Back to [[#IPv6 Configuration]]
 
Back to [[#IPv6 Configuration]]
  
 
==Tools and sample output==
 
==Tools and sample output==
 +
{{Warning box|The output of some tools and in logfiles may expose IPv6 addresses.
 +
Some addresses contain a modified MAC address or globally addressable IPv6 addresses.
 +
When posting output to a public form, consider camouflaging them.}}
 +
 +
Additional information is available logs for <code>mythbackend</code>
 +
and <code>mythfrontend</code> if the <code>--loglevel debug</code>
 +
option is used.
 +
 +
<pre>
 +
mythbackend --verbose general --nodblog --quiet \
 +
    --logpath /var/log/mythtv --loglevel debug
 +
</pre>
 +
 +
IPv6 addresses in the logs don't follow the
 +
convention that allows consecutive 0:0s to be represented by ::.
 +
So, the address used in this page: <code>fd01:a:b:1::123</code>
 +
will appear as <code>fd01:a:b:1:0:0:0:123</code>.
 +
This is not a problem, only a convention used by the underlying
 +
<code>Qt</code> code.
  
 
These examples are all from a host with <code>mythbackend</code>
 
These examples are all from a host with <code>mythbackend</code>
 
running and IPv6 configured. MySQL is running and using IPv4.
 
running and IPv6 configured. MySQL is running and using IPv4.
 
Obviously, these tools can be run on frontends and slave backends.
 
Obviously, these tools can be run on frontends and slave backends.
 
{{Warning box|The output of some tools and in logfiles may expose IPv6 addresses.
 
Some addresses contain a modified MAC address or globally addressable IPv6 addresses.
 
When posting output to a public form, consider camouflaging them.}}
 
  
 
To make sure <code>mythbackend</code> and <code>mysqld</code>
 
To make sure <code>mythbackend</code> and <code>mysqld</code>
 
are listening for connections:
 
are listening for connections:
  
<code>sudo netstat -pant | egrep '3306|6543'</code>
+
<code>sudo netstat -Wpant | egrep '3306|6543'</code>
  
 
When the backend is running, but no slave backends/frontends are connected, expect:
 
When the backend is running, but no slave backends/frontends are connected, expect:
Line 176: Line 224:
 
could be blocking access.
 
could be blocking access.
  
<code>nmap -P0 -p 3306,6543 -6 --reason someHostName</code>
+
<code>nmap -P0 -p 6543 -6 --reason someHostName</code>
  
 
The expected response is:
 
The expected response is:
 
<pre>
 
<pre>
 
PORT    STATE SERVICE REASON
 
PORT    STATE SERVICE REASON
3306/tcp closed mysql  conn-refused
 
 
6543/tcp open  mythtv  syn-ack
 
6543/tcp open  mythtv  syn-ack
 
</pre>
 
</pre>
 
Port 3306 fails in this test, as expected, because the MySQL version used
 
doesn't support IPv6 (remove the <code>-6</code> flag above and this will work.)
 
 
Additional information is available from both <code>mythbackend</code>
 
and <code>mythfrontend</code> if the <code>--loglevel debug</code> is
 
used.
 
 
<pre>
 
mythbackend --verbose general --nodblog --quiet \
 
    --logpath /var/log/mythtv --loglevel debug
 
</pre>
 
 
IPv6 addresses in the logs will have a-f in upper case and the
 
convention that allows consecutive 0s to be represented by ::
 
isn't used. So, the address used in this page: <code>fd01:a:b:1::123</code>
 
will appear as <code>FD01:A:B:1:0:0:0:123</code>.
 
  
 
Back to [[#IPv6 Configuration]]
 
Back to [[#IPv6 Configuration]]

Revision as of 21:36, 16 February 2012


Important.png Note: 0.25 allows users the option of connecting to mythbackend via IPv6. To be clear, enabling IPv6 isn't required for successful operation of MythTV.

This Wiki shows how to activate IPv6. It is part of significant changes in the way MythTV binds to sockets which should be transparent to users.

IPv6 Configuration

Interfaces typically have multiple IPv6 addresses. For help picking the right one, see #Which IPv6 address should be used?.

If IPv6 is known to be working, just complete the following. Otherwise, see #Basics.

Stop all frontends and backends.

Using mythtv-setup on the master backend, go to the General page and enter the address of choice.

The configuration of someone who just upgraded to 0.25 will look like this:

Local Backend
    IP address:   192.168.1.123
    IPv6 address: ::1

Master Backend
    IP address: 192.168.1.123

Change it to look like this:

Local Backend
    IP address:   192.168.1.123
    IPv6 address: fd01:a:b:1::123

Master Backend
    IP address: fd01:a:b:1::123

The existing IPv4 address shouldn't be changed/removed, as some services still require it.

The pre 0.25 convention that requires both Local Backend and Master Backend addresses to be the same in order for a backend to be considered a master backend still applies. It has been expanded to allow for the Master Backend address to equal either the Local IPv4 or IPv6 Backend address.

Some (non MythTV) programs require their IPv6 addresses enclosed in brackets ([]) or the addition of a trailing percent sign and Zone Index (e.g. %eth0.) Neither of these should be used with MythTV.

Use mythtv-setup to configure any slave backends with their own IPv6 addresses.

Restart the backend(s).

Which IPv6 address should be used?

The most likely choice is a Unique Local Address (ULA.) Use ULA's if all access to the backend will be within a LAN.

Note that even though ULAs are global addresses, no self respecting router will pass them out on the internet, much like IPv4 Private Network addresses (e.g. 192.168.1.123.)

Use a search engine and look for: 'Unique Local Address generator' to find a site that will create ULAs correctly like this, for example.

For details on constructing ULAs see RFC 4193.

MythTV must have a globally routeble IPv6 address (e.g. 2001:db8::1) configured only if it is necessary to run MythTV from a frontend/slave over the internet.

Site Local (fec0::/10) addresses were deprecated in 2004.

Host (::1) addresses are only useful for a stand alone system.

Since all Link Local addresses have the same prefix (fe80::/10), they require a Zone Index (e.g. %eth0) for routing and shouldn't be used. MythTV will automatically ignore these addresses.

To list currently assigned IPv6 addresses, type: ifconfig | grep inet6

inet6 addr: ::1/128 Scope:Host
inet6 addr: fe80::222:22ff:fe22:2222/64 Scope:Link
inet6 addr: fd01:a:b:1::123/64 Scope:Global
inet6 addr: 2001:db8::123/64 Scope:Global

In the above, the 3rd address is probably the best choice. It is also probably one that must be assigned manually.

If the desired address doesn't exist, use the configuration tool provided with the host's distribution to add it.

Entries in /etc/hosts (DHCP, router etc.) are optional. The following is an example for one host:

192.168.1.123              masterbe.local    masterbe
fd01:a:b:1::123            masterbe.local    masterbe
2001:db8::123              masterbe.local    masterbe

Back to #IPv6 Configuration

Basics

Verify that IPv6 is active on each MythTV host.

If ssh, for example, is known to work, a simple test (run from the master backend) is:

for HOST in <list all frontend and slave backends here>
do  ssh -6 $HOST hostname
done

If the test works for all frontends and slave backends, IPv6 can be added to MythTV.

If the above fails, see the following section.

Back to #IPv6 Configuration

What if there's a problem

  • Make sure IPv6 hasn't been disabled either system wide or for the interface MythTV will use. Type:

sysctl -a 2> /dev/null | grep "ipv6.*disable"

net.ipv6.conf.all.disable_ipv6 = 0
net.ipv6.conf.default.disable_ipv6 = 0
net.ipv6.conf.lo.disable_ipv6 = 0
net.ipv6.conf.eth0.disable_ipv6 = 0
  • Some distributions keep these options in files under /etc/sysctl.d.
  • Be sure any firewalls have been adjusted to accept the IPv6 addresses being used.
  • If the MythTV configuration is correct, but no IPv6 traffic is seen during, for example recording playback, Master Backend Override may be enabled in mythtv-setup General section and the Master Backend IP address is still set to an IPv4 address.

Back to #IPv6 Configuration

Tools and sample output

Warning.png Warning: The output of some tools and in logfiles may expose IPv6 addresses. Some addresses contain a modified MAC address or globally addressable IPv6 addresses. When posting output to a public form, consider camouflaging them.

Additional information is available logs for mythbackend and mythfrontend if the --loglevel debug option is used.

mythbackend --verbose general --nodblog --quiet \
    --logpath /var/log/mythtv --loglevel debug

IPv6 addresses in the logs don't follow the convention that allows consecutive 0:0s to be represented by ::. So, the address used in this page: fd01:a:b:1::123 will appear as fd01:a:b:1:0:0:0:123. This is not a problem, only a convention used by the underlying Qt code.

These examples are all from a host with mythbackend running and IPv6 configured. MySQL is running and using IPv4. Obviously, these tools can be run on frontends and slave backends.

To make sure mythbackend and mysqld are listening for connections:

sudo netstat -Wpant | egrep '3306|6543'

When the backend is running, but no slave backends/frontends are connected, expect:

tcp   0  0  0.0.0.0:3306            0.0.0.0:*      LISTEN      1198/mysqld     
tcp   0  0  192.168.1.123:6543      0.0.0.0:*      LISTEN      26961/mythbackend
tcp   0  0  127.0.0.1:6543          0.0.0.0:*      LISTEN      26961/mythbackend
tcp6  0  0  fd01:a:b:1::123:6543    :::*           LISTEN      26961/mythbackend
tcp6  0  0  ::1:6543                :::*           LISTEN      26961/mythbackend

With one frontend connected and playing a recording, expect:

tcp   0  0 0.0.0.0:3306           0.0.0.0:*              LISTEN      1384/mysqld     
tcp   0  0 192.168.1.123:6543     0.0.0.0:*              LISTEN      26961/mythbackend
tcp   0  0 127.0.0.1:6543         0.0.0.0:*              LISTEN      26961/mythbackend
tcp   0  0 192.168.1.123:3306     192.168.1.234:56538    ESTABLISHED 1384/mysqld     
tcp   0  0 192.168.1.123:3306     192.168.1.234:56601    ESTABLISHED 1384/mysqld     
tcp   0  0 192.168.1.123:6543     192.168.1.234:42760    ESTABLISHED 26961/mythbackend
tcp   0  0 192.168.1.123:6543     192.168.1.234:42761    ESTABLISHED 26961/mythbackend
tcp   0  0 192.168.10.204:3306    192.168.1.234:56532    ESTABLISHED 1384/mysqld     
tcp6  0  0 fd01:a:b:1::123:6543   fd01:a:b:1::456:36345  ESTABLISHED 26961/mythbackend
tcp6  0  0 fd01:a:b:1::123:6543   fd01:a:b:1::456:36346  ESTABLISHED 26961/mythbackend
tcp6  0  0 ::1:6543               :::*                   LISTEN      26961/mythbackend

If installed, nmap may help diagnose the reason that a connection fails. For example, a firewall could be blocking access.

nmap -P0 -p 6543 -6 --reason someHostName

The expected response is:

PORT     STATE SERVICE REASON
6543/tcp open   mythtv  syn-ack

Back to #IPv6 Configuration