Yes, it's normal:
ifconfig eth0
or
ifconfig ens33
Look for the "inet6" line.
and test via lsof:
[root@srv]# lsof -i :443
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
httpd 15319 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 26197 root 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 26218 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 26219 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 26220 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 26310 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 80303 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 107496 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 112527 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
httpd 128430 nobody 8u IPv6 5287623 0t0 TCP *:https (LISTEN)
[root@srv]# lsof -i :80
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
httpd 15319 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 26197 root 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 26218 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 26219 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 26220 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 26310 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 80303 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 107496 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 112527 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
httpd 128430 nobody 4u IPv6 5287612 0t0 TCP *:http (LISTEN)
If you would like to disable IPv6, add these lines to /etc/sysctl.conf
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
and run
sysctl -p
Then confirm with:
ifconfig eth0
or
ifconfig ens33