Refuse responding to broadcasts request

Securing and Optimizing Linux: RedHat Edition -A Hands on Guide
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# 5.25. Refuse responding to broadcasts request

As for the ping request, it's also important to disable broadcast request. When a packet is sent to an IP broadcast address (i.e. 192.168.1.255) from a machine on the local network, that packet is delivered to all machines on that network. Then all the machines on a network respond to this ICMP echo request and the result can be severe network congestion or outages -denial-of-service attacks. See the RFC 2644 for more information.

                  [root@deep] /# echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts

You can add this line in your `/etc/rc.d/rc.local` file so the command will be automatically set if your system reboots.

Edit the `/etc/sysctl.conf` file and add the following line:

                  # Enable ignoring broadcasts request
                  net.ipv4.icmp_echo_ignore_broadcasts = 1

You must restart your network for the change to take effect. The command to restart the network is the following:

To restart all networks devices manually on your system, use the following command:

                  [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 ]`

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