Bug 711827

Hmmm, I found that if I moved my /etc/gai.conf out of the way, ping6 started working.


$ sudo mv /etc/gai.conf /etc/gai.conf.OLD

$ ping6 -v -n -c 1 www.google.com
PING www.google.com(2001:4860:b009::69) 56 data bytes
64 bytes from 2001:4860:b009::69: icmp_seq=1 ttl=54 time=67.3 ms


My gai.conf only had defaults in it, though:

$ cat /etc/gai.conf
precedence  ::1/128       50
precedence  ::/0          40
precedence  2002::/16     30
precedence ::/96          20
precedence ::ffff:0:0/96  100

I have this problem on a 32-bit F15.

$ rpm -q --file `which ping6`
iputils-20101006-7.fc15.i686

$ host orange.kame.net
orange.kame.net has address 203.178.141.194
orange.kame.net has IPv6 address 2001:200:dff:fff1:216:3eff:feb1:44d7

$ ping6 orange.kame.net
PING orange.kame.net(::57.0.0.0) 56 data bytes
ping: sendmsg: Address family not supported by protocol

$ host ipv6.l.google.com
ipv6.l.google.com has IPv6 address 2a00:1450:4001:c01::68

$ ping6 ipv6.l.google.com
PING ipv6.l.google.com(fra07s07-in-x68.1e100.net) 56 data bytes
64 bytes from fra07s07-in-x68.1e100.net: icmp_seq=1 ttl=58 time=61.1 ms


The symptoms when there are both IPv4 and IPv6 addresses are the same as when there is only an IPv4 address:

$ host freshmeat.net
freshmeat.net has address 216.34.181.101

$ ping6 freshmeat.net
PING freshmeat.net(::57.0.0.0) 56 data bytes
ping: sendmsg: Address family not supported by protocol


strace shows that ping6 tries to use the IPv4 address even though there is an IPv6 address:

# strace -f -e sendto ping6 orange.kame.net
sendto(4, "\24\0\0\0\26\0\1\3\324\245\357M\0\0\0\0\0\0\0\0", 20, 0, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 20
PING orange.kame.net(::57.0.0.0) 56 data bytes
sendto(3, "\200\0\0\0\7\333\0\1\324\245\357M\325\212\2\0\10\t\n\v\f\r\16\17\20\21\22\23\24\25\26\27"..., 64, 0, {sa_family=AF_INET, sin_port=htons(58), sin_addr=inet_addr("203.178.141.194")}, 28) = -1 EAFNOSUPPORT (Address family not supported by protocol)
ping: sendmsg: Address family not supported by protocol

Works for me fine on F15 as well as F14 (with & without gai.conf). If your issue is affected by gai.conf it will relate to glibc. What's NVR of your's installed glibc?

I'm running with glibc-2.14-2.

$ rpm -qa glibc\* | sort
glibc-2.14-2.i686
glibc-2.14-2.x86_64
glibc-common-2.14-2.x86_64
glibc-devel-2.14-2.x86_64
glibc-headers-2.14-2.x86_64


Just to double-check, I tried again.  Without gai.conf, it works:

$ ls /etc/gai.conf
ls: cannot access /etc/gai.conf: No such file or directory

$ ping6 -n -c 1 www.kame.net
PING www.kame.net(2001:200:dff:fff1:216:3eff:feb1:44d7) 56 data bytes
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=1 ttl=52 time=182 ms

--- www.kame.net ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 182.051/182.051/182.051/0.000 ms


But with gai.conf, it fails:

$ sudo mv /etc/gai.conf.bak /etc/gai.conf

$ cat /etc/gai.conf
label  ::1/128       0
label  ::/0          1
label  2002::/16     2
label ::/96          3
label ::ffff:0:0/96  4
precedence  ::1/128       50
precedence  ::/0          40
precedence  2002::/16     30
precedence ::/96          20
precedence ::ffff:0:0/96  100

$ ping6 -n -c 1 www.kame.net
PING www.kame.net(::) 56 data bytes
ping: sendmsg: Address family not supported by protocol

--- www.kame.net ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms

getaddrinfo() doesn't seem to be honoring the hints which tell it to retrieve IPv6 addresses only.

Below is a simple program that calls getaddrinfo() on www.kame.net with hints.ai_family restricted to AF_INET6 only, but it prints out both IPv4 and IPv6 addresses.

$ ./getaddrinfo-example 
203.178.141.194
203.178.141.194
203.178.141.194
2001:200:dff:fff1:216:3eff:feb1:44d7
2001:200:dff:fff1:216:3eff:feb1:44d7
2001:200:dff:fff1:216:3eff:feb1:44d7



$ cat getaddrinfo-example.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>

int main(void)
{
    struct addrinfo *result;
    struct addrinfo *res;
    struct addrinfo hint;
    int error;

    memset(&hint, 0, sizeof(struct addrinfo));
    hint.ai_family = AF_INET6;
    hint.ai_socktype = 0;
    hint.ai_protocol = 0;
    hint.ai_flags = 0;

    /* resolve the domain name into a list of addresses */
    error = getaddrinfo("www.kame.net", NULL, &hint, &result);
    if (error != 0)
    {
        fprintf(stderr, "error in getaddrinfo: %s\n", gai_strerror(error));
        return EXIT_FAILURE;
    }

    /* loop over all returned results and print the addresses */
    for (res = result; res != NULL; res = res->ai_next)
    {
        void *addr;
        char address[64] = "";
        if (res->ai_family == AF_INET) {
           addr = &((struct sockaddr_in *)(res->ai_addr))->sin_addr;
        } else if (res->ai_family == AF_INET6) {
           addr = &((struct sockaddr_in6 *)(res->ai_addr))->sin6_addr;
        }
        inet_ntop(res->ai_addr->sa_family, addr, address, 64);
        printf("%s\n", address);
    }

    freeaddrinfo(result);
    return EXIT_SUCCESS;
}

The above test program correctly returns the IPv6 address only on a RHEL 6.1 system with glibc-2.12-1.25.el6.x86_64

Changing component to glibc.

Downgrading to 2.13.90-9 fixes it (it shows only the IPv6 addresses); upgrading back to 2.14-2 breaks it again (it shows both IPv4 and IPv6 addresses).

$ sudo yum downgrade glibc-2.13.90-9 \
                     glibc-common-2.13.90-9 \
                     glibc-devel-2.13.90-9 \
                     glibc-headers-2.13.90-9 \
                     nscd-2.13.90-9
...

$ rpm -q glibc
glibc-2.13.90-9.x86_64
glibc-2.13.90-9.i686

$ ./getaddrinfo-example-hints
2001:200:dff:fff1:216:3eff:feb1:44d7
2001:200:dff:fff1:216:3eff:feb1:44d7
2001:200:dff:fff1:216:3eff:feb1:44d7

$ sudo yum -y update glibc
...

$ rpm -q glibc
glibc-2.14-2.x86_64
glibc-2.14-2.i686

$ ./getaddrinfo-example-hints                         
203.178.141.194
203.178.141.194
203.178.141.194
2001:200:dff:fff1:216:3eff:feb1:44d7
2001:200:dff:fff1:216:3eff:feb1:44d7
2001:200:dff:fff1:216:3eff:feb1:44d7

glibc-2.14-3 has been submitted as an update for Fedora 15.
https://admin.fedoraproject.org/updates/glibc-2.14-3

Package glibc-2.14-3:
* should fix your issue,
* was pushed to the Fedora 15 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing glibc-2.14-3'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/glibc-2.14-3
then log in and leave karma (feedback).

glibc-2.14-3 has been pushed to the Fedora 15 stable repository.  If problems still persist, please make note of it in this bug report.