Ubuntu
eglibc package

  1. Bug #417757
  2. Comment #274

Comment 274 for bug 417757

Revision history for this message
Martin Pitt (pitti) wrote : Re: [Bug 417757] Re: [karmic regression] all network apps / browsers suffer from multi-second delays by default due to IPv6 DNS lookups

Tollef Fog Heen [2010-04-14 20:15 -0000]:
> If it works fine with Karmic and works fine with Lucid with IPv6
> disabled, but is slow at resolving DNS with IPv6 enabled, that is this
> bug.

Oh, interesting. I have such a buggy router as well, and in karmic it
was fixed with local-ipv6-lookup.diff.

ipv6.disable=1 does not make any difference for me in Lucid (I haven't
tested that with karmic, since the eglibc in karmic-updates fixed it)

> In grub, add «ipv6.disable=1» after the line with loads the kernel (this
> one presumably ends with «quiet splash»).

The option was recognized, dmesg says "IPv6: Loaded, but
administratively disabled", and "ip a" dropped the "inet6" lines as
well. But the 20 second DNS resolution timeout still happens.

> Can you include the output of running «ip a» in your reply as well?
> Preferably both before and after disabling IPv6.

Before:
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN qlen 1000
    link/ether 00:1d:72:df:71:c3 brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 00:17:c4:53:a9:f8 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.109/24 brd 192.168.2.255 scope global wlan0
    inet6 fe80::217:c4ff:fe53:a9f8/64 scope link
       valid_lft forever preferred_lft forever

After:
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN qlen 1000
    link/ether 00:1d:72:df:71:c3 brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 00:17:c4:53:a9:f8 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.109/24 brd 192.168.2.255 scope global wlan0

Matthias Klose [2010-04-16 0:16 -0000]:
> There's a eglibc testbuild prepared; it's tested to install and survive
> a reboot; if you want to test it, please add to /etc/apt/sources.list:
>
> deb http://ppa.launchpad.net/ubuntu-toolchain/ppa/ubuntu lucid main

Makes no difference here. Is that still the same patch as
local-ipv6-lookup.diff in karmic-updates?

The only workaround which works fine for me is to change DNS server. I
have a script /etc/network/if-up.d/0nameserver which overwrites
/etc/resolv.conf to use my providers' DNS servers instead of my
router.