[Nut-upsuser] NUT fails on openSUSE 11.3 if IPv6 turned off

[Arjen de Korte]

Citeren Roger Price <roger op rogerprice.org>:

> By default IPv6 is turned on in openSUSE 11.3.  I visited YaST ->
> Network Settings -> Global options and deselected "Enable IPv6".  I
> then restarted the box.  When I entered the command "rcupsd start" to
> start NUT, I received the reply:
>
> Starting NUT UPS drivers ....done
> Starting NUT UPS server startproc:  exit status of parent of  
> /usr/sbin/upsd: 1
> ....failed
>
> File /var/log/messages tails with
>
> Nov  7 09:53:57 glacon usbhid-ups[4974]: Startup successful
> Nov  7 09:53:57 glacon upsd[4977]: listening on 127.0.0.1 port 3493
> Nov  7 09:53:57 glacon upsd[4977]: not listening on ::1 port 3493
> Nov  7 09:53:59 glacon usbhid-ups[4974]: Signal 15: exiting
>
> The fix for this problem is to turn IPv6 on again, but I wondered if
> there was a way of specifying to NUT "no IPv6".

Yes. If NUT was compiled with both IPv4 and IPv6 enabled, you can  
force it to listen on a specific interface by appending '-4' (IPv4) or  
'-6' (IPv6). This isn't in the man page for upsd, but will be in the  
list of options that are displayed when you type 'upsd -h'.  
Alternatively, you can enter the sockets it should listen to with the  
LISTEN directive in 'upsd.conf'. This will then override the build in  
defaults (which is a good idea anyway). See 'man 5 upsd.conf'.

> By the way, why is NUT sensitive to IPv6 operation?

A couple of releases ago we decided to no longer listen on all  
interfaces, but instead only on the loopback interface. This in order  
to not automatically expose the upsd service on systems that are  
connected to the internet (which is a security risk if you don't  
protect the communication through SSL). In order to allow the least  
amount of surprises for people that are upgrading their systems, we  
decided to listen to both the IPv4 and IPv6 loopback addresses if IPv6  
support is detected at compilation time. In most of the cases, there  
is really no benefit to switch off IPv6 and in the rare cases there  
is, there is an option that can be passed to the upsd server to  
override this default.

Best regards, Arjen
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