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Ip/mac binding, Ip/mac binding” on – Fortinet FortiGate 100 User Manual

Page 166

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166

Fortinet Inc.

Configuring IP/MAC binding for packets going through the firewall

Firewall configuration

IP/MAC binding

IP/MAC binding protects the FortiGate unit and your network from IP spoofing attacks.
IP spoofing attempts to use the IP address of a trusted computer to connect to or
through the FortiGate unit from a different computer. The IP address of a computer
can easily be changed to a trusted address, but MAC addresses are added to
Ethernet cards at the factory and cannot easily be changed.

You can enter the static IP addresses and corresponding MAC addresses of trusted
computers in the Static IP/MAC table.

If you have trusted computers with dynamic IP addresses that are set by the FortiGate
DHCP server, the FortiGate unit adds these IP addresses and their corresponding
MAC addresses to the Dynamic IP/MAC table. See

“Providing DHCP services to your

internal network” on page 119

. The dynamic IP/MAC binding table is not available in

Transparent mode.

IP/MAC binding can be enabled for packets connecting to the firewall or passing
through the firewall.

This section describes:

Configuring IP/MAC binding for packets going through the firewall

Configuring IP/MAC binding for packets going to the firewall

Adding IP/MAC addresses

Viewing the dynamic IP/MAC list

Enabling IP/MAC binding

Configuring IP/MAC binding for packets going through the firewall

Use the following procedure to use IP/MAC binding to filter packets that would
normally be allowed through the firewall by a firewall policy.

1

Go to Firewall > IP/MAC Binding > Setting.

2

Select Enable IP/MAC binding going through the firewall.

3

Go to Firewall > IP/MAC Binding > Static IP/MAC.

4

Select New to add IP/MAC binding pairs to the IP/MAC binding list.

All packets that would normally be allowed through the firewall by a firewall policy are
first compared with the entries in the IP/MAC binding list. If a match is found, then the
firewall attempts to match the packet with a policy.

Note: If you enable IP/MAC binding and change the IP address of a computer with an IP or
MAC address in the IP/MAC list, you must also change the entry in the IP/MAC list or the
computer will not have access to or through the FortiGate unit. You must also add the IP/MAC
address pair of any new computer that you add to your network or this computer will not have
access to or through the FortiGate unit.