Title

The Juniper router must be configured to have Gratuitous ARP disabled on all external interfaces. (Cat II impact)

Discussion

A gratuitous ARP is an ARP broadcast in which the source and destination MAC addresses are the same. It is used to inform the network about a host IP address. A spoofed gratuitous ARP message can cause network mapping information to be stored incorrectly, causing network malfunction.

Check Content

Review the configuration to determine if gratuitous ARP is disabled on all external interfaces. [edit interfaces] <external interface> { no-gratuitous-arp-reply; no-gratuitous-arp-request; unit <number> { family inet { address <IPv4 address>/<mask>; } family inet6 { address <IPv6 address>/<mask>; } } } If gratuitous ARP is enabled on any external interface, this is a finding.

Fix Text

Disable gratuitous ARP on all external interfaces. set interfaces <external interface> no-gratuitous-arp-reply set interfaces <external interface> no-gratuitous-arp-request set interfaces <external interface> unit <number> family inet address <IPv4 address>/<mask> set interfaces <external interface> unit <number> family inet6 address <IPv6 address>/<prefix>

Additional Identifiers

Rule ID: SV-254032r844129_rule

Vulnerability ID: V-254032

Group Title: SRG-NET-000362-RTR-000111

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.