IP Source Guard provides source IP address filtering on a Layer 2 port to prevent a malicious host from impersonating a legitimate host by assuming the IP address of the legitimate host.
IP Source Guard uses dynamic DHCP snooping and static IP source binding to match IP addresses to hosts on untrusted Layer 2 access ports. At first, all IP traffic on the protected port is blocked except for DHCP packets. After a client receives an IP address from the DHCP server, or after s static IP source binding is configured, all traffic with that IP source address is permitted from that client. Traffic from other hosts is denied. This filtering limits a host's ability to attack the network by claiming a neighbor host's IP address.