This option will alert you to all bad error messages in your network.
[root@deep] /#echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses
Add the above commands to the /etc/rc.d/rc.local
script file and you'll not have to type it again the next time you
reboot your system.
Edit the /etc/sysctl.conf file and add the following line:
# Enable bad error message Protection
net.ipv4.icmp_ignore_bogus_error_responses = 1
You must restart your network for the change to take effect. The command to manually restart the network is the following:
[root@deep] /# /etc/rc.d/init.d/network restart
Setting network parameters [ OK ]
Bringing up interface lo [ OK ]
Bringing up interface eth0 [ OK ]
Bringing up interface eth1 [ OK ]