How can I disable ping replies?

Applications IP Networking
2

you can use:

iptables -A OUTPUT -p icmp --icmp-type 8 -j DROP

you can also try this (I never used personally):

echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_all

OR do it permanently on sysctl.conf

vi /etc/sysctl.conf
net.ipv4.icmp_echo_ignore_all = 1

hope this helps