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  ]