FVS338 ProSafe VPN Firewall 50 Re ference Manual
4-26 Firewall Protection and Content Filtering
v1.0, March 2008
6. When you have completed adding MAC addresses, click Apply to save your settings.

IP/MAC Binding

IP/MAC Binding allows you to bind an IP to a MAC address and vice-versa. Some machines are
configured with static addresses. To prevent users from changing their static IP addresses, IP/MAC
Binding must be enabled on the router. If the router sees packets with a matching IP address, but
with an inconsistent MAC address (or vice-versa), it will drop these packets. If users have enabled
the logging option for IP/MAC Binding, these packets will be logged before they are dropped. The
router will then display the total number of dropped packets that violated either the IP-to-MAC
Binding or the MAC-to-IP Binding.
Example: If three computers on the LAN are set up as follows:
Host1: MAC address (00:01:02:03:04:05) and IP address (192.168.10.10)
Host2: MAC address (00:01:02:03:04:06) and IP address (192.168.10.11)
Host3: MAC address (00:01:02:03:04:07) and IP address (192.168.10.12)
If all the above host entries are added to the IP/MAC Binding table, the following scenarios
indicate the possible outcome.
Host1: Matching IP & MAC address in IP/MAC Table.
Host2: Matching IP but inconsistent MAC address in IP/MAC Table.
Host3: Matching MAC but inconsistent IP address in IP/MAC Table.
The router will block the traffic coming from Host2 and Host3, but allow the traffic coming from
Host1 to any external network. The total count of dropped packets will be displayed.
To invoke the IP/MAC Binding Table screen:
1. Select Security from the main menu and IP/MAC Binding from the sub-menu. The IP/MAC
Binding screen will display.