Understanding IP Spoofing

One method of attempting to gain access to a restricted area of the network is to insert a false source address in the packet header to make the packet appear to come from a trusted source. This technique is called IP spoofing. The mechanism to detect IP spoofing relies on route table entries. For example, if a packet with source IP address 10.1.1.6 arrives at ge-0/0/1, but JUNOS Software has a route to 10.1.1.0/24 through ge-0/0/0, a check for IP spoofing discovers that this address arrived at an invalid interface as defined in the route table. A valid packet from 10.1.1.6 can only arrive via ge-0/0/0, not ge-0/0/1. Therefore, JUNOS Software concludes that the packet has a spoofed source IP address and discards it.

Related Topics

• JUNOS Software Feature Support Reference for SRX Series and J Series Devices