sysctl -a 2>/dev/null | grep disable_ipv6

net.ipv6.conf.all.disable_ipv6 = 0
net.ipv6.conf.default.disable_ipv6 = 0
net.ipv6.conf.enp1s0.disable_ipv6 = 0
net.ipv6.conf.enp2s0.disable_ipv6 = 0
net.ipv6.conf.enp3s0.disable_ipv6 = 0
net.ipv6.conf.enp4s0.disable_ipv6 = 0
net.ipv6.conf.lo.disable_ipv6 = 0

Si net.ipv6.conf.all.disable_ipv6 = 1 alors IPv6 est désactivé de façon globale sur le serveur.