Description:

What we have in /etc/hosts related to IPv6 is

::1 localhost.localdomain localhost

and that's not sufficient, it makes some IPv6 capable tools not being able to use localhost (most notably ab [http://httpd.apache.org/docs/2.2/programs/ab.html] but also seen with the IPv6 enabled git version of glusterfs [https://github.com/gluster/glusterfs]).

The proper configuration for localhost would be the one described here:

http://www.bieringer.de/linux/IPv6/IPv6-HOWTO/IPv6-HOWTO-6.html

Additional info:

* package version(s): filesystem 2011.04-1, referred /etc/hosts file is http://projects.archlinux.org/svntogit/packages.git/tree/filesystem/trunk/hosts?id=b8efbc3c43bf9c8f60edb684e680567427ea0b30

Steps to reproduce:

* Start a http server on localhost, eg.:

ruby -rwebrick -e 's=WEBrick::HTTPServer.new(:Port => 8001 ); s.mount_proc("/") { |rq, rs| rs.body="hello world" }; %w[TERM INT].each { |sig| trap(sig) { s.shutdown }; s.start }'

* Try to reach the local httpd with ab:

ab http://localhost:8001/

* Actual result:

Benchmarking localhost (be patient)...apr_socket_recv: Connection refused (111)

* Expected result:

Benchmarking localhost (be patient).....done


Server Software: WEBrick/1.3.1
Server Hostname: localhost
Server Port: 8001

Document Path: /
Document Length: 11 bytes

Concurrency Level: 1
Time taken for tests: 0.006 seconds
Complete requests: 1
Failed requests: 0
Write errors: 0
Total transferred: 154 bytes
HTML transferred: 11 bytes
Requests per second: 180.05 [#/sec] (mean)
Time per request: 5.554 [ms] (mean)
Time per request: 5.554 [ms] (mean, across all concurrent requests)
Transfer rate: 27.08 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 0
Processing: 5 5 0.0 5 5
Waiting: 5 5 0.0 5 5
Total: 6 6 0.0 6 6

* Fix: using the configuration suggested in the IPv6 Howto (cited above) fixes the problem.