Disable ICMP Timestamp Response Ubuntu LTS

Disable ICMP Timestamp Response Ubuntu LTS

### Disable ICMP Timestamp Response Ubuntu LTS ###

# sysctl disable tcp_timestamps
echo 0 > /proc/sys/net/ipv4/tcp_timestamps && \
echo "net.ipv4.tcp_timestamps = 0" > /etc/sysctl.d/tcp_timestamps.conf && \
sysctl -p && \
sysctl -a | grep "net\.ipv4\.tcp_timestamps"

# open icmp to specified segment
iptables -A INPUT -s 10.10.0.0/16 -p icmp -m icmp --icmp-type 8 -j ACCEPT

# delete icmp echo-request
iptables -D ufw-before-forward -p icmp -m icmp --icmp-type 8 -j ACCEPT && \
iptables -D ufw-before-input -p icmp -m icmp --icmp-type 8 -j ACCEPT

# check icmp echo-request
iptables -L | grep icmp | grep echo-request

# check by ping
ping YourServerIPv4