Trying to resolve hosts using localhost errors out for ipv6 attempts: $ host www.seznam.cz localhost ;; communications error to ::1#53: connection refused ;; communications error to ::1#53: connection refused Using domain server: Name: localhost Address: 127.0.0.1#53 Aliases:
www.seznam.cz has address 77.75.77.222 www.seznam.cz has address 77.75.79.222 ;; communications error to ::1#53: connection refused ;; communications error to ::1#53: connection refused www.seznam.cz has IPv6 address 2a02:598:a::79:222 www.seznam.cz has IPv6 address 2a02:598:2::1222 ;; communications error to ::1#53: connection refused ;; communications error to ::1#53: connection refused
It's because on some distros (like openSUSE), localhost is defined both as 127.0.0.1 and ::1.
So listen on ::1 too. This makes ipv4-switchoff easier. /etc/resolv.conf should likely be updated to contain ::1 eventually too (see update_dns()).
Fixes: #1188