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I installed Google chrome browser on Fedora 18. Now when I try update softwares using yum upgrade, it report the following error and I can't get chrome updated.

http://dl.google.com/linux/chrome/rpm/stable/x86_64/repodata/repomd.xml: [Errno 14] curl#7 - "Failed to connect to 2404:6800:4005:c00::88: Network is unreachable"

It looks like dl.google.com is resolved to an IPv6 address, but I don't use IPv6, and ping dl.google.com returns an IPv4 address as expected.

# ping dl.google.com
PING dl.l.google.com (74.125.128.93) 56(84) bytes of data.

What's the possible reason, and how can I fix this?

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Not sure about other implementations of ping, but at least the ping from iputils only uses IPV4, ping6 uses IPv6. – Wieland Mar 20 at 19:59

2 Answers

up vote 1 down vote

I don't know about yum. Sounds like it's missing an implementation of Happy Eyeballs, i.e. fallback to ipv4. There is an ipv6 address...

$ host dl.google.com
dl.google.com is an alias for dl.l.google.com.
dl.l.google.com has address 173.194.34.132
...many randomly permuted addresses...
dl.l.google.com has address 173.194.34.137
dl.l.google.com has IPv6 address 2a00:1450:400c:c06::5d

Apparently there's a workaround for when this goes wrong, which is to edit /etc/gai.conf and uncomment the line precedence ::ffff:0:0/96 100. This gives precedence to ipv4 addresses.

I think normally it should just work. You'll have a link-local ipv6 address, but a site-local ipv4 address (or a public one without NAT). The libc DNS resolver should then prefer ipv4 destinations. This is specified in RFC 3484.

I wonder if this is a Teredo-style problem. Has your router (e.g. an Apple Airport) assigned you a global IPV6 address through an unreliable tunnel? My computer (no global ipv6) looks like this:

$ ip addr |grep inet6
    inet6 ::1/128 scope host 
    inet6 fe80::215:afff:fe9f:fcd2/64 scope link
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weird, yum provides "/etc/gai.conf" said it's in glibc package, I've already installed glibc, but I don't have gai.conf file under /etc. This's a gai.conf file under /usr/share/doc/glibc-common-2.16 which comes from glibc-common package – LiuYan 刘研 Mar 21 at 3:52
my router is TP-Link WRT841N, it only understand IPv4. ip addr shows inet6 entries, but they're already there before (i probably refuse to use IPv6 in my life, i don't need it). – LiuYan 刘研 Mar 21 at 4:03
created /etc/gai.conf manually with the following content: reload yes precedence ::ffff:0:0/96 100, but i still got same error – LiuYan 刘研 Mar 21 at 4:57
up vote 0 down vote

You can completely disable IPv6 by adding

net.ipv6.conf.all.disable_ipv6 = 1

to a file in /etc/sysctl.d, for example /etc/sysctl.d/disable-ipv6.conf.

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well, i added this config, restart computer, and ip addr does not show inet6 entries anymore, but the error still occurs. – LiuYan 刘研 Mar 21 at 15:45

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