Re: disable IPV6?

[Brian Krahmer]

>  Curious why more people haven't reported this. Is it card
>  related? Network related? Is IPV6 on for everyone, but for
>  some reason it's not causing everyone a problem? 
Personally, I would like to see an option in the setup for whether you want
to enable IPV6 or not, with the default being Not.  At least, until IPV6
becomes a reality for mainstream users.

I noticed that we are both on comcast.  I didn't play around with nslookup
or dig, but perhaps comcast' dns servers are actually returning IPV6
addresses for some hosts.  If we're getting v6 addresses, but can't connect
to them because we haven't got a tunnel set up, it would explain the delays,
as it attempts a v6 connection, fails, then falls back to v4.

brian

disable IPV6?

[Daniel Roesen]

On Fri, Mar 05, 2004 at 04:02:11PM -0800, Brian Krahmer wrote:
>  Personally, I would like to see an option in the setup for whether
> you want
>  to enable IPV6 or not, with the default being Not.  At least, until IPV6
>  becomes a reality for mainstream users. 
I beg to differ, the default should be on.

>  I noticed that we are both on comcast.  I didn't play around with
> nslookup
>  or dig, but perhaps comcast' dns servers are actually returning IPV6
>  addresses for some hosts.  If we're getting v6 addresses, but can't connect
>  to them because we haven't got a tunnel set up, it would explain the delays,
>  as it attempts a v6 connection, fails, then falls back to v4. 
There should be no delays. If IPv6 is enabled for the interfaces, there
are two options (currently):

- default route via stateless autoconfig (router advertisement)
- static default route

So unless you _have_ IPv6 outside connectivity (either by some router on
your LAN advertising a default route to your host or by yourself
configuring a static IPv6 default route), there is no default route and
any attempt to connect to an IPv6 address outside your local LAN will
_immediately_ result in a "no route to host" and thus a failure. Without
noticable delay.

Guys... VARs are today shipping even laptops with Windows XP with IPv6
enabled by default.

If someone has long timeout delays, there is something misconfigured...
e.g. a static default to a nonexistant default router. THIS needs to
be fixed.


Regards,
Daniel

disable IPV6?

[Derek Tattersall]

* Brian Krahmer (brian(a)krahmer.com) [040306 06:39]:
>  From: "Brian Krahmer" <brian(a)krahmer.com&gt;
>  To: "Fedora (E-mail)" <fedora-test-list(a)redhat.com&gt;
>  Subject: Re: disable IPV6?
>  Message-ID: <000c01c4030e$49050df0$0200a8c0@WARHOLE>
>  X-Mailer: Microsoft Outlook CWS, Build 9.0.6604 (9.0.2911.0)
>  Reply-To: fedora-test-list(a)redhat.com
>  Date: Fri, 5 Mar 2004 16:02:11 -0800
>  
>  > Curious why more people haven't reported this. Is it card
>  > related? Network related? Is IPV6 on for everyone, but for
>  > some reason it's not causing everyone a problem?
>  
>  Personally, I would like to see an option in the setup for whether you want
>  to enable IPV6 or not, with the default being Not.  At least, until IPV6
>  becomes a reality for mainstream users.
>  
>  I noticed that we are both on comcast.  I didn't play around with nslookup
>  or dig, but perhaps comcast' dns servers are actually returning IPV6
>  addresses for some hosts.  If we're getting v6 addresses, but can't connect
>  to them because we haven't got a tunnel set up, it would explain the delays,
>  as it attempts a v6 connection, fails, then falls back to v4.
>  
>  brian
>  
>  
>  
>  
>  -- 
>  fedora-test-list mailing list
>  fedora-test-list(a)redhat.com
>  To unsubscribe: 
>  http://www.redhat.com/mailman/listinfo/fedora-test-list
>   
    I've found that ad.doubleclick.net does not properly handle AAAA
    queries.  The progressively longer timeouts occur until the maximum
    number  arrive, and the requestor shrugs and continues in ipv4.  The
    problem is actually with doubleclick.  If they'd just fix their
    DNS...
-- 
Derek Tattersall   | Accordion, n.:  A bagpipe with pleats. 
                   | 
dlt(a)mebtel.net     | 
                   | 
dlt666(a)yahoo.com   |

disable IPV6?

[Randy L Schrickel]

Daniel Roesen wrote:

>  So unless you _have_ IPv6 outside connectivity (either by some router
> on
>  your LAN advertising a default route to your host or by yourself
>  configuring a static IPv6 default route), there is no default route and
>  any attempt to connect to an IPv6 address outside your local LAN will
>  _immediately_ result in a "no route to host" and thus a failure. Without
>  noticable delay. 
>  If someone has long timeout delays, there is something
> misconfigured...
>  e.g. a static default to a nonexistant default router. THIS needs to
>  be fixed. 
Here's the output from a dnslookup, ifconfig, and 'netstat -rn' on my
box, with just IPV4 configured followed by the IPV6 results (as setup by
the Fedora install):

IPV4:

   0.000000 192.168.0.100 -> 68.54.80.5   DNS Standard query A
www.google.com
   0.011393   68.54.80.5 -> 192.168.0.100 DNS Standard query response
CNAME www.g
oogle.akadns.net A 216.239.39.147 A 216.239.39.104 A 216.239.39.99


eth0      Link encap:Ethernet  HWaddr 00:01:03:C1:D1:BE
           inet addr:192.168.0.100  Bcast:192.168.0.255  Mask:255.255.255.0
           inet6 addr: fe80::201:3ff:fec1:d1be/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:51 errors:0 dropped:0 overruns:0 frame:0
           TX packets:51 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:9416 (9.1 Kb)  TX bytes:4229 (4.1 Kb)
           Interrupt:10 Base address:0xd400

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt
Iface
192.168.0.0     0.0.0.0         255.255.255.0   U         0 0          0
eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
0.0.0.0         192.168.0.1     0.0.0.0         UG        0 0          0
eth0


And here's the IPV6 version:
   0.000000 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
www.google.com
   5.000097 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
www.google.com
   5.010537   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.g
oogle.akadns.net
   5.010918 192.168.0.100 -> 68.54.80.5   DNS Standard query A 
www.google.com
   5.024892   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.g
oogle.akadns.net A 216.239.39.104 A 216.239.39.99 A 216.239.39.147
   5.025460 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
104.39.239.216.i
n-addr.arpa
  10.025349 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
104.39.239.216.i
n-addr.arpa
  10.039552   68.54.80.5 -> 192.168.0.100 DNS Standard query response, 
No such na
me
  10.039963 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
www.google.com
  10.050470   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.g
oogle.akadns.net
  10.051063 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
99.39.239.216.in
-addr.arpa
  15.050580 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
99.39.239.216.in
-addr.arpa

(that was from loading http://www.google.com Note the AAAA responses)

eth0      Link encap:Ethernet  HWaddr 00:01:03:C1:D1:BE
           inet addr:192.168.0.100  Bcast:192.168.0.255  Mask:255.255.255.0
           inet6 addr: fe80::201:3ff:fec1:d1be/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:123 errors:0 dropped:0 overruns:0 frame:0
           TX packets:163 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:68112 (66.5 Kb)  TX bytes:17927 (17.5 Kb)
           Interrupt:10 Base address:0xd400

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt 
Iface
192.168.0.0     0.0.0.0         255.255.255.0   U         0 0          0 
eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
0.0.0.0         192.168.0.1     0.0.0.0         UG        0 0          0 
eth0

Routing looks the same in either case. /etc/resolv.conf is the same for 
both, namely this:

; generated by /sbin/dhclient-script
nameserver 68.54.80.5


If there's something else in the config that's needed, without shutting 
off ipv6, that'd be fine. I just wanted to get my net connection working 
the way it should, and turning ipv6 off did the trick. .Any other tests 
or suggestions?

Thanks,
randy

disable IPV6?

[Daniel Roesen]

On Sat, Mar 06, 2004 at 03:10:42PM -0500, Randy Schrickel wrote:
>  Here's the output from a dnslookup, ifconfig, and 'netstat
> -rn' on my
>  box, with just IPV4 configured followed by the IPV6 results (as setup by
>  the Fedora install): 
Who is doing the DNS lookup?

>  eth0      Link encap:Ethernet  HWaddr 00:01:03:C1:D1:BE
>             inet addr:192.168.0.100  Bcast:192.168.0.255  Mask:255.255.255.0
>             inet6 addr: fe80::201:3ff:fec1:d1be/64 Scope:Link 
As you can see, IPv6 is enabled in the kernel. Otherwise you would
have no inet6 link-local addr.

Please show "ip addr show dev eth0" to make sure we have all the info.

>  Kernel IP routing table 
With "netstat -rn" you look up only IPv4 routes. Use "netstat -A inet6
-rn" or (much better): "ip -6 route".

>  And here's the IPV6 version:
>     0.000000 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
>  www.google.com 
68.54.80.5 is being asked for AAAA RR but gives no reply. Retry:

>     5.000097 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA
>
>  www.google.com
>     5.010537   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
>  CNAME www.g
>  oogle.akadns.net 
Now it answers with the CNAME. I'm seeing the same effect from here:

; <<>> DiG 9.2.3 <<>> www.google.com AAAA
[...]
;; ANSWER SECTION:
www.google.com.         3600    IN      CNAME   www.google.akadns.net.
[...]
;; Query time: 4727 msec

Why the resolver doesn't do an AAAA query for www.google.akadns.net.
consequently, is beyond me. Looks like a bug.

Instead of following the CNAME, it asks for an A RR:

>     5.010918 192.168.0.100 -> 68.54.80.5   DNS Standard query A 
>  www.google.com
>     5.024892   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
>  CNAME www.g
>  oogle.akadns.net A 216.239.39.104 A 216.239.39.99 A 216.239.39.147 
There, Akamai's DNS servers answer directly with A RRs for the CNAME.

>     5.025460 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
>  104.39.239.216.in-addr.arpa
>    10.025349 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
>  104.39.239.216.in-addr.arpa
>    10.039552   68.54.80.5 -> 192.168.0.100 DNS Standard query response, 
>  No such name 
Interesting. Same "no response to first query" problem on a simple
PTR query. Nothing IPv6 specific here.

>    10.039963 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA
>
>  www.google.com
>    10.050470   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
>  CNAME www.g
>  oogle.akadns.net 
This one goes quickly... 68.54.80.5 has the answer cached.

>  (that was from loading http://www.google.com Note the AAAA responses)
There are ne AAAA responses, but only a CNAME.

Actually, I see nothing going wrong IPv6-specific. There are two
pretty normal IPv4 DNS queries not being answered - one of them even
asking for a normal PTR RR, not even AAAA.

This will be probably tricky to debug properly.

Are those two different installations? Or how do you toggle "IPv6
enabled" (whatever that actually means - as both systems are obviously
IPv6 enabled per se).

IPv6 transport is not involved, but pls show "ip -6 route" anyway.

>  If there's something else in the config that's needed,
> without shutting 
>  off ipv6, that'd be fine. I just wanted to get my net connection working 
>  the way it should, and turning ipv6 off did the trick. .Any other tests 
>  or suggestions? 
Currently, it looks like 68.54.80.5 or your network's NAT is misbehaving
somehow. What kind of device is doing the NAT?


Best regards,
Daniel

disable IPV6?

[Randy L Schrickel]

Daniel Roesen wrote:

>  Please show "ip addr show dev eth0" to make sure we have
> all the info. 
I'm at work now, no access to the machine having the problem. So I'll 
skip over all the command output you asked for right now. I can do 
those from home later today, but I'll answer the questions that don't 
need access to the machine.

>  Are those two different installations? Or how do you toggle
> "IPv6
>  enabled" (whatever that actually means - as both systems are obviously
>  IPv6 enabled per se). 
It's a single installation. FC1 worked fine, the Win XP side when I 
dual boot works fine. I "disable IPv6" by adding the line

alias net-pf-10 off

to my /etc/modprobe.conf file as mentioned earlier in this thread.

My original issue was incredibly slow DNS. Looking at things across 
systems with ethereal showed those multiple AAAA messages. That lead 
me to wondering if it was something strange going on with ipv6 on my 
machine, so I wanted to "turn it off" as a test. Adding that line to 
the file did "turn it off", and DNS was fine.

>  Currently, it looks like 68.54.80.5 or your network's NAT is
> misbehaving
>  somehow. What kind of device is doing the NAT? 
It's a D-Link wireless access point (but the machine in question isn't 
  wireless). I get the same result whether I point my DNS to the 
d-link (as dhcp configures it) or if I point it to the upstream 
comcast address.

Thanks for the input Daniel.

randy

disable IPV6?

[Daniel Roesen]

On Mon, Mar 08, 2004 at 06:26:35AM -0500, Randy L Schrickel wrote:
>  It's a single installation. FC1 worked fine, the Win XP side when
> I 
>  dual boot works fine. I "disable IPv6" by adding the line
>  
>  alias net-pf-10 off
>  
>  to my /etc/modprobe.conf file as mentioned earlier in this thread. 
Well, but your second ifconfig output shows clearly, that there is
an IPv6 link-local address assigned to eth0, which happens only if
the IPv6 kernel module gets loaded. So in fact, your box _was_ IPv6
enabled in both cases.


Best regards,
Daniel

disable IPV6?

[Randy L Schrickel]

Daniel Roesen wrote:

>  Well, but your second ifconfig output shows clearly, that there is
>  an IPv6 link-local address assigned to eth0, which happens only if
>  the IPv6 kernel module gets loaded. So in fact, your box _was_ IPv6
>  enabled in both cases. 
Oops. Nope, that was just a bad cut and paste job on my part. The 
inet6 addresses definitely don't show up when I do the ifconfig with 
the ipv6 "disabled". My mistake. Will try it again tonight, correctly. 
I think it looks the same, except no inet6 addr. Sorry for the 
misleading info!

randy

disable IPV6?

[Randy L Schrickel]

Daniel Roesen wrote:

>  Try:
>  ip -6 route del default dev eth0
>  
>  and try wether you still get those timeouts. 
Ok, I did that. Hmmmm, interesting....

nslookup www.google.com

159.905296 192.168.0.100 -> 68.54.80.5   DNS Standard query A www.google.com
164.906050 192.168.0.100 -> 68.54.80.5   DNS Standard query A www.google.com
164.918972   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.google.akadns.net A 64.233.161.104 A 64.233.161.99

nslookup www.amazon.com199.788366 192.168.0.100 -> 68.54.80.5   DNS 
Standard query A www.amazon.com
199.800101   68.54.80.5 -> 192.168.0.100 DNS Standard query response A 
207.171.185.16

Definitely makes a difference for some (most?) web pages, but not all. 
cnn.com for instance took minutes to load, and spewed out hundreds of 
dns lines in my ethereal trace.

lynx www.google.com

620.363071 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
www.google.com
620.374913   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.google.akadns.net
620.392936 192.168.0.100 -> 68.54.80.5   DNS Standard query A www.google.com
620.405477   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.google.akadns.net A 216.239.37.147 A 216.239.37.104 A 
216.239.37.99
620.430031 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
www.google.com
625.432955 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
www.google.com
625.445163   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.google.akadns.net
625.445556 192.168.0.100 -> 68.54.80.5   DNS Standard query A www.google.com
625.469632   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
CNAME www.google.akadns.net A 216.239.37.99 A 216.239.37.147 A 
216.239.37.104

Removing that default route certainly has an effect - but it doesn't 
seem to be a consistent one. Does that output help?

(really appreciate you (daniel) and whoever else actually takes the time 
to look at this!)

Thanks,
randy

disable IPV6?

[Daniel Roesen]

On Tue, Mar 09, 2004 at 10:23:04PM -0500, Randy Schrickel wrote:
>  Removing that default route certainly has an effect - but it
> doesn't 
>  seem to be a consistent one. Does that output help? 
Not really. There seems to be a certain pattern that always the first
query to a certain name server may time out. Are you sure that the
v6 default route _really_ makes a difference, or is that just
coincidence? Can you reproduce results by re-adding the default etc?

I seriously have not the slightest clue why v6 should make ANY
difference, given that all I'm ssing from these outputs is pure
IPv4 stuff. And it's not some antipathy of your ISP's DNS cache against
AAAA RRs as (if I'm not mistaken) even A RR requests timed out.

One serious problem with debugging is that your ISP's cache might
be the problem, or the remote nameservers. Your box only qeries
the ISP cache, but we have no clue what THIS one does with your
query in order to deliver results.

Can you try installing a local BIND as local cache and use 127.0.0.1
as resolver in /etc/resolv.conf, and try that?


Best regards,
Daniel

disable IPV6?

[Randy L Schrickel]

Daniel Roesen wrote:

>  Not really. There seems to be a certain pattern that always the
> first
>  query to a certain name server may time out. Are you sure that the
>  v6 default route _really_ makes a difference, or is that just
>  coincidence? Can you reproduce results by re-adding the default etc? 
I can try re-adding the default.

>  I seriously have not the slightest clue why v6 should make ANY
>  difference, given that all I'm ssing from these outputs is pure
>  IPv4 stuff. And it's not some antipathy of your ISP's DNS cache against
>  AAAA RRs as (if I'm not mistaken) even A RR requests timed out. 
Me either. This is my first experience with v6. It just showed up as the 
only noticeable difference, and taking it out fixed the problem.

>  Can you try installing a local BIND as local cache and use 127.0.0.1
>  as resolver in /etc/resolv.conf, and try that? 
Haven't done that before, but I can give it a try.

randy

disable IPV6?

[Randy L Schrickel]

Randy Schrickel wrote:

>  (really appreciate you (daniel) and whoever else actually takes the
> time 
>  to look at this!) 
It's been a couple weeks, and I'm still playing with this, so I thought
I'd post my latest news (solution?). Someone (thanks Ricky) emailed me a
nice link for testing "internet speed" that should be pretty DNS
intensive - http://www.numion.com/YourSpeed . Even though my last fix
seemed to help, that website told me I was only getting about 30-50 kbps
download speeds. The same machine, dual booted into Windows XP Pro came
out about 350kbps!

So I finally did something tonight I've been thinking of - unplugging my
  "wireless broadband router" (a D-Link DI-614+) and plugging the cable
modem directly into the PC. It's been cabled to the D-Link, not wireless
on this machine. Wow. My speed to that site now came up between 400 and
500 kbps! Cool. Except my wife wouldn't be happy with no wireless to the
other PC, so this won't do.

I decided to flash upgrade the router bios to see if that makes a
difference. So I did that, and re-connected to the router. Now I'm
getting at least 350kbps! Current bios version is "2.20, Tue 19 Aug 
2003" and I've got kernel 2.6.3-2.1.253. I also wrote to D-Link's tech 
support, and they suggested that I change the 614's MTU to 1492. I 
haven't tried that, but I'm not sure it will help any more - from what 
I've read, that value should be used for DSL (PPoE).

I haven't tried it yet with "ipv6 enabled" to see if that original 
setting makes any difference at all now. Interestingly, I found this 
link 
http://www.experts-exchange.com/Networking/Linux_Networking/Q_20868797.html 
which talks about the same problem I've described only with Mandrake. 
Their solution - disable ipv6, just like I'd done before!

Sorry for the long posting, but I like to be complete. ;) I'll probably 
post my results again after I re-enable ipv6.

Thanks to all who have helped and offered suggestions.

randy

disable IPV6?

[Randy L Schrickel]

Randy Schrickel wrote:

> http://www.experts-exchange.com/Networking/Linux_Networking/Q_20868797.html 
>  which talks about the same problem I've described only with Mandrake. 
>  Their solution - disable ipv6, just like I'd done before! 
Minor correction, that link refers to the same issue with SUSE, not 
Mandrake.

randy

disable IPV6?

[Randy L Schrickel]

Randy Schrickel wrote:

> >
> http://www.experts-exchange.com/Networking/Linux_Networking/Q_20868797.html 
> > which talks about the same problem I've described only with Mandrake. 
> > Their solution - disable ipv6, just like I'd done before! 
Rebooted with ipv6 enabled, looks like the speed is still right up 
there. Not as good as without the D-Link, but it's usable now.

randy

disable IPV6?

[Gene Smith]

Randy Schrickel wrote, On 03/26/2004 11:03 PM:
>  Randy Schrickel wrote:
>  
> >> http://www.experts-exchange.com/Networking/Linux_Networking/Q_20868797.html 
> >> which talks about the same problem I've described only with Mandrake. 
> >> Their solution - disable ipv6, just like I'd done before!
>  
>  
>  Rebooted with ipv6 enabled, looks like the speed is still right up 
>  there. Not as good as without the D-Link, but it's usable now.
>  
>  randy 
Randy,
Sorry to contact you at home but not sure if you are still monitoring 
this list.

Was wondering if upgrading your D-Link unit still looks like the right 
solution for you, even with ipv6 re-enabled. Any idea why XP was getting 
good results with the original d-link firmware while fc2 did not?

I don't have a D-link router but a homebrew Bering-Leaf router (LRP) on 
a old PC. It contains a program called dnscache which I use as my dns 
server. It works a lot faster when ipv6 is disabled in fc2t2 and I might 
need to find out if it can be upgraded to handle the AAAA record better 
too, like possibly your d-link now does.

Just thought I'd ask.

Tks,
-gene