Tested on RCPL35: The 'netstat' utility throws "getnameinfo failed" (with 'UNKNOWN' address) when it can't resolve ipv6 address to name, but in the same situation for ipv4 addresses it just prints values in the numeric format. This issue with 'netstat' was fixed in the original 'net-tools' 30-sep-2013 https://github.com/ecki/net-tools/commit/a70c568b907d23ec2cf7defc81be50c351968f12 with a note: -------------------- lib/inet6.c:INET6_rresolve() - various fixes 1) Fall-back to numeric address if getnameinfo fails. Reverse lookup is not mandatory, therefore its fail is not an error. Just return numeric address in that case. This makes netstat/route show IPv6 address instead of [UNKNOWN] in case of DNS problems. -------------------- cat /etc/hosts 127.0.0.1 localhost -------------------------------------------------------------------------------- When the ntp service is running bound to interfaces with ipv4 and ipv6 addresses: === root@eqm01s07p2 GPB ~ # netstat -na | grep -e 'failed' -e '123' udp 0 0 127.0.0.254:123 0.0.0.0:* udp 0 0 127.0.0.1:123 0.0.0.0:* udp 0 0 0.0.0.0:123 0.0.0.0:* udp6 0 0 ::1:123 :::* udp6 0 0 :::123 :::* -------------------------------------------------------------------------------- === root@eqm01s07p2 GPB ~ # netstat -a | grep -e 'failed' -e 'ntp' udp 0 0 127.0.0.254:ntp *:* udp 0 0 127.0.0.254:ntp *:* udp 0 0 localhost:ntp *:* udp 0 0 *:ntp *:* getnameinfo failed udp6 0 0 [UNKNOWN]:ntp [::]:* udp6 0 0 [::]:ntp [::]:* --------------------------------------------------------------------------------
