Libguestfs - Jan 2014 - Re: [PATCH] appliance: Disable ipv6 in the appliance because qemu usernet is ipv4 only

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---

Untested in this environment.

 appliance/init | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/appliance/init b/appliance/init
index b25ea26..cc8c978 100755
--- a/appliance/init
+++ b/appliance/init
@@ -71,6 +71,10 @@ for f in /sys/block/{h,s,ub,v}d*/queue/scheduler; do echo
noop > $f; done
 # Update the system clock.
 hwclock -u -s
 
+# Disable ipv6 because host names resolve to ipv4 and ipv6
+# Resolver may prefer ipv6 and qemu usernet does only ipv4
+for f in /proc/sys/net/ipv6/conf/*/disable_ipv6; do if test -w $f ; then echo 1
> $f; fi; done
+
 # Set up the network.
 ip addr add 127.0.0.1/8 brd + dev lo scope host
 ip link set dev lo up

On Thu, Jan 23, Olaf Hering wrote:
> +++ b/appliance/init
>  # Update the system clock.
>  hwclock -u -s
Why is that needed? Just wondering...


Olaf

On Thu, Jan 23, 2014 at 11:46:33PM +0100, Olaf Hering
wrote:
> On Thu, Jan 23, Olaf Hering wrote:
> 
> > +++ b/appliance/init
> >  # Update the system clock.
> >  hwclock -u -s
> 
> Why is that needed? Just wondering...
I suspect it's not needed at all.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines.  Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://people.redhat.com/~rjones/virt-top

On Thu, Jan 23, 2014 at 11:44:52PM +0100, Olaf Hering
wrote:
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> ---
> 
> Untested in this environment.
> 
>  appliance/init | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/appliance/init b/appliance/init
> index b25ea26..cc8c978 100755
> --- a/appliance/init
> +++ b/appliance/init
> @@ -71,6 +71,10 @@ for f in /sys/block/{h,s,ub,v}d*/queue/scheduler; do
echo noop > $f; done
>  # Update the system clock.
>  hwclock -u -s
>  
> +# Disable ipv6 because host names resolve to ipv4 and ipv6
> +# Resolver may prefer ipv6 and qemu usernet does only ipv4
> +for f in /proc/sys/net/ipv6/conf/*/disable_ipv6; do if test -w $f ; then
echo 1 > $f; fi; done
There's no error checking in init, so this should work:

  for f in /proc/sys/net/ipv6/conf/*/disable_ipv6; do echo 1 > $f; done

However I don't understand why disabling IPv6 should be necessary.  If
sites resolve to AAAA+A records, then presumably it's going to choose
the A (IPv4) route since no IPv6 route exists.  If a site resolves to
only an AAAA record, then it's not reachable whatever we do.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines.  Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://people.redhat.com/~rjones/virt-top

On Fri, Jan 24, Richard W.M. Jones wrote:
> However I don't understand why disabling IPv6 should be necessary.  If
> sites resolve to AAAA+A records, then presumably it's going to choose
> the A (IPv4) route since no IPv6 route exists.  If a site resolves to
> only an AAAA record, then it's not reachable whatever we do.
For me the code tries to reach the ipv6 address, which wont work.

Olaf