Arista MLS EOS 4.2x Router Security Technical Implementation Guide
Rules, Groups, and Values defined within the XCCDF Benchmark
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The Arista router must be configured to have Internet Control Message Protocol (ICMP) unreachable notifications disabled on all external interfaces.
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Host unreachable ICMP ...Rule Medium Severity -
SRG-NET-000362-RTR-000114
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The Arista router must be configured to have Internet Control Message Protocol (ICMP) mask replies disabled on all external interfaces.
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Mask Reply ICMP messag...Rule Medium Severity -
SRG-NET-000362-RTR-000115
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The Arista router must be configured to have Internet Control Message Protocol (ICMP) redirects disabled on all external interfaces.
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Redirect ICMP messages...Rule Medium Severity -
SRG-NET-000362-RTR-000117
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SRG-NET-000362-RTR-000118
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The Arista BGP router must be configured to limit the prefix size on any inbound route advertisement to /24 or the least significant prefixes issued to the customer.
The effects of prefix de-aggregation can degrade router performance due to the size of routing tables and also result in black-holing legitimate traffic. Initiated by an attacker or a misconfigured...Rule Low Severity -
SRG-NET-000362-RTR-000120
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The multicast Rendezvous Point (RP) Arista router must be configured to limit the multicast forwarding cache so that its resources are not saturated by managing an overwhelming number of Protocol Independent Multicast (PIM) and Multicast Source Discovery Protocol (MSDP) source-active entries.
MSDP peering between networks enables sharing of multicast source information. Enclaves with an existing multicast topology using PIM-SM can configure their RP routers to peer with MSDP routers. As...Rule Low Severity -
SRG-NET-000362-RTR-000123
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SRG-NET-000362-RTR-000124
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The Arista BGP router must be configured to enable the Generalized TTL Security Mechanism (GTSM).
GTSM is designed to protect a router's IP-based control plane from DoS attacks. Many attacks focused on CPU load and line-card overload can be prevented by implementing GTSM on all Exterior Border ...Rule Low Severity -
SRG-NET-000364-RTR-000109
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SRG-NET-000364-RTR-000110
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The Arista perimeter router must be configured to block inbound packets with source Bogon IP address prefixes.
Bogons include IP packets on the public internet that contain addresses that are not in any range allocated or delegated by the Internet Assigned Numbers Authority (IANA) or a delegated regional in...Rule Medium Severity -
SRG-NET-000364-RTR-000111
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The Arista perimeter router must be configured to have Link Layer Discovery Protocols (LLDPs) disabled on all external interfaces.
LLDPs are primarily used to obtain protocol addresses of neighboring devices and discover platform capabilities of those devices. Use of SNMP with the LLDP Management Information Base (MIB) allows ...Rule Low Severity -
SRG-NET-000364-RTR-000112
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The Arista perimeter router must be configured to have Proxy ARP disabled on all external interfaces.
When Proxy ARP is enabled on a Cisco router, it allows that router to extend the network (at Layer 2) across multiple interfaces (LAN segments). Because proxy ARP allows hosts from different LAN se...Rule Medium Severity -
SRG-NET-000364-RTR-000113
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SRG-NET-000512-RTR-000007
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SRG-NET-000364-RTR-000114
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The Arista multicast Designated Router (DR) must be configured to filter the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Report messages to allow hosts to join only multicast groups that have been approved by the organization.
Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone doing a file download here or there), whereas multicast can have b...Rule Low Severity -
SRG-NET-000364-RTR-000115
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The Arista multicast Designated Router (DR) must be configured to filter the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Report messages to allow hosts to join a multicast group only from sources that have been approved by the organization.
Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone doing a file download here or there), whereas multicast can have b...Rule Medium Severity -
SRG-NET-000364-RTR-000116
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The Arista Multicast Source Discovery Protocol (MSDP) router must be configured to only accept MSDP packets from known MSDP peers.
MSDP peering with customer network routers presents additional risks to the DISN Core, whether from a rogue or misconfigured MSDP-enabled router. To guard against an attack from malicious MSDP traf...Rule Medium Severity -
SRG-NET-000512-RTR-000001
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SRG-NET-000512-RTR-000002
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SRG-NET-000512-RTR-000003
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SRG-NET-000512-RTR-000004
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The MPLS router must be configured to have TTL propagation disabled.
The head end of the label-routered path (LSP), the label edge router (LER) will decrement the IP packet's time-to-live (TTL) value by one and then copy the value to the MPLS TTL field. At each labe...Rule Medium Severity -
SRG-NET-000512-RTR-000005
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SRG-NET-000512-RTR-000006
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The PE router must be configured to have each Virtual Routing and Forwarding (VRF) instance with the appropriate Route Target (RT).
The primary security model for an MPLS L3VPN as well as a VRF-lite infrastructure is traffic separation. Each interface can only be associated to one VRF, which is the fundamental framework for tra...Rule High Severity -
SRG-NET-000512-RTR-000008
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The PE router providing MPLS Virtual Private Wire Service (VPWS) must be configured to have the appropriate virtual circuit identification (VC ID) for each attachment circuit.
VPWS is an L2VPN technology that provides a virtual circuit between two PE routers to forward Layer 2 frames between two customer-edge routers or routers through an MPLS-enabled IP core. The ingres...Rule High Severity -
SRG-NET-000512-RTR-000011
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The Arista Multicast Source Discovery Protocol (MSDP) router must be configured to use its loopback address as the source address when originating MSDP traffic.
Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of MSDP routers. It is easier to construct appropriate ingress filters fo...Rule Low Severity -
SRG-NET-000512-RTR-000012
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The Arista router must be configured to advertise a hop limit of at least 32 in Router Advertisement messages for IPv6 stateless auto-configuration deployments.
The Neighbor Discovery protocol allows a hop limit value to be advertised by routers in a Router Advertisement message being used by hosts instead of the standardized default value. If a very small...Rule Low Severity -
SRG-NET-000512-RTR-000013
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The Arista router must not be configured to use IPv6 Site Local Unicast addresses.
As currently defined, site local addresses are ambiguous and can be present in multiple sites. The address itself does not contain any indication of the site to which it belongs. The use of site-lo...Rule Medium Severity -
SRG-NET-000512-RTR-000014
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The Arista perimeter router must be configured to suppress Router Advertisements on all external IPv6-enabled interfaces.
Many of the known attacks in stateless autoconfiguration are defined in RFC 3756 were present in IPv4 ARP attacks. To mitigate these vulnerabilities, links that have no hosts connected such as the ...Rule Medium Severity -
SRG-NET-000205-RTR-000015
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The perimeter router must be configured to block all packets with any IP options.
Packets with IP options are not fast routered and henceforth must be punted to the router processor. Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of p...Rule Medium Severity -
SRG-NET-000205-RTR-000016
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The PE router must be configured to ignore or block all packets with any IP options.
Packets with IP options are not fast routered and therefore must be punted to the router processor. Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of pa...Rule Medium Severity
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