What is IP Address ::1 ?

Jonathan Ryshpan jonrysh at pacbell.net
Thu Mar 18 02:03:41 UTC 2010


Fetchmail produced a number of errors like:
        connection to localhost:smtp [::1/25] failed: Connection
        refused.
These appeared to be caused by this /etc/hosts file:
        127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
        ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
which has two possible resolutions for localhost, one of which, namely "::1",
isn't recognized.  I attempted to fix things by eliminating the "::1"
line, to produce the hosts file:
        127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
But using this file causes mounts on /media to fail (in my case a
detachable hard drive and a camera).
Both problems are cured with this hosts file:
        127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
        ::1         localhost6 localhost6.localdomain6

All this seems related to IPV6 configuration, but how isn't clear to me.
Can anyone elucidate?  Should I file a bug against the
original /etc/hosts ?

Thanks - jon




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