Control Plane Security Configuration

As highlighted above, there are two fundamental mechanisms how traffic is redirected to the CPU, via protocol ACLs, and via route lookup. These are addressed in following two sections.

Secure Control Plane Traffic via Protocol ACLs

This section describes the configuration options for control plane traffic that is redirected to the CPU via protocol ACLs. These ACLs are automatically created by the protocols, and do not need to be - and cannot be - configured manually. For example if you configure a routing protocol like BGP, the required ACLs to match and punt the BGP packets to the control plane are created automatically.

Enabling the Control Plane Security Feature

By default, all packets matching the protocol ACLs will be sent to the control plane without any rate limit, except for PPPoE. The RBFS Control Plane Security feature allows to add policers to all protocol ACLs. If enabled, this feature creates a set of default policers, and applies them to the protocol ACLs. Thereby the control plane gets secured against DDoS attacks matching these ACLs.

Syntax:

set forwarding-options control-plane-security <attribute> <value>

Attribute Description

state (enable|disable)

Enable or disable the control-plane security feature. Default: enable.

Example:

{
    "rtbrick-config:forwarding-options": {
      "control-plane-security": {
        "state": "enable"
      }
    }
}

Configuring Host Path QoS

The host-path-qos enable feature is disabled by default. Once it is enabled, you cannot disable it.

To enable the `host-path-qos' feature, enter the following command:

Syntax:

set forwarding-options class-of-service control-plane-qos ingress-qos <attribute> <value>

Attribute Description

state (enable|disable)

Enable or disable the host path QoS feature. Default: disabled.

Example

supervisor@rtbrick>LEAF01: cfg> show config forwarding-options class-of-service control-plane-qos
{
    "rtbrick-config:control-plane-qos": {

      "ingress-qos": {
        "state": "enable"
      }
    }
  }

By enabling this feature, the default scheduler and queue configurations are installed and the CPU ports queue mapping will change. Also, all control plane ACLs will be reprogrammed to update action_forward_class.

Marking Outbound Control Plane Traffic

RBFS enables you to configure the various protocols to mark the egress control plane traffic. The control plane traffic can be marked with type-of-service (ToS) values.

  • For BGP, OSPF, RADIUS, PIM, L2TPv2, and DHCP protocols, the remark-type should be configured as ToS

  • For the IGMP and PPPoE protocols, the remark-type can be be configured as p-bit or tos

  • The outbound-marking attributes such as name, code-point and remark-type are mandatory

  • If the name of the protocol is L2-all, then the remark-type should configured as p-bit

  • If the name of the protocol is L3-all, then the remark-type should configured as tos

  • Redundancy related control traffic can be marked with specific tos value with the L3-all option

set forwarding-options class-of-service control-plane-qos outbound-marking protocol <protocol-name> <remark-type-value> codepoint <codepoint-value>

Option Description

<protocol-name>

Specifies the protocol name.

<remark-type-value>

Specifies the remark type value that can be p-bit or tos.

<codepoint-value>

Specifies the codepoint value. The supported range for p-bit outbound-marking is 0-7.

Example: Marking Outbound CP Traffic Configuration

supervisor@rtbrick>LEAF01: cfg> show config
{
  "ietf-restconf:data": {
    "rtbrick-config:forwarding-options": {
      "class-of-service": {
        "control-plane-qos": {
          "outbound-marking": {
            "protocol": [
              {
                "protocol": "bgp",
                "remark-type": "tos",
                "codepoint": 192
              },
              {
                "protocol": "dhcp",
                "remark-type": "p-bit",
                "codepoint": 5
              },
              {
                "protocol": "l3-all",
                "remark-type": "tos",
                "codepoint": 224
              },
			        {
                "protocol": "igmp",
                "remark-type": "p-bit",
                "codepoint": 7
              },
              {
                "protocol": "igmp",
                "remark-type": "tos",
                "codepoint": 192
              },
              {
                "protocol": "ppp",
                "remark-type": "p-bit",
                "codepoint": 7
              },
              {
                "protocol": "ppp",
                "remark-type": "tos",
                "codepoint": 192
              },
              {
                "protocol": "radius",
                "remark-type": "tos",
                "codepoint": 100
            }
            ]
          }
        }
      }
    }
  }
}

Restricting Management Access

If you enable inband management access for example via SSH, protocol ACLs will be created that match on the enabled protocols and redirect the management traffic to the control plane. By default, this traffic is not restricted in terms of source IP addresses. You can optionally restrict management access to trusted IP addresses by applying a source prefix list. An additional match condition will then be added to the protocol ACLs for inband management.

Configuring a Prefix List

Syntax:

set forwarding-options prefix-list <options>

Option Description

<prefix-list-name> ipv4-prefix <ipv4_prefix>

Prefix list configuration for IPv4.

<prefix-list-name> ipv6-prefix <ipv6_prefix>

Prefix list configuration for IPv6.

Applying a Prefix List

Syntax:

set inband-management instance <instance-name> source-prefix-list <list-name>

Example: Inband Management Configuration with Source Prefix List

"rtbrick-config:inband-management": {
      "instance": [
        {
          "name": "default",
          "ssh": "true",
          "ntp": "true",
          "source-prefix-list": "list1"
        }
      ]
    },

"rtbrick-config:forwarding-options": {
      "prefix-list": [
        {
          "prefix-list-name": "list1",
          "ipv4-prefix": [
            {
              "ipv4-prefix": "198.51.100.100/24"
            },
            {
              "ipv4-prefix": "198.51.100.33/24"
            },
            {
              "ipv4-prefix": "198.51.100.44/24"
            }
          ]
        }
The inband management is provided to only the source address specified in the prefix list if the prefix list is configured. If the prefix list not configured, it works for all source IPs. Also, the prefix addresses configured should be of /32.

Configuring Protocol ACL Options

This section describes how to configure policers per protocol and configure match on IPv4 ToS or IPv6 TC fields for protocol ACLs.

  • If control plane security is disabled, this configuration has no effect in the system

  • Protocol-specific configuration will take priority over ALL configuration in the control-plane-security protocol

Syntax:

set forwarding-options control-plane-security protocol <protocol-name> <attribute> <value>

Option Description

protocol <protocol-name>

Name of the protocol. You can configure individual protocols, and/or all protocols using the 'ALL' value keyword.

match-tc <tc-value>

Configure IPv6 TC value. The range is 0 to 248.

match-tos <tos-value>

Configure IPv4 ToS value. The range is 0 to 248.

policer <policer>

Configure policer name.

Example:

{
  "ietf-restconf:data": {
    "rtbrick-config:forwarding-options": {
      "class-of-service": {
        "policer": [
          {
            "policer-name": "_DEFAULT_POLICER_BGP_LL",
            "flags": "color-blind",
            "level1-rates": {
              "cir": 1000,
              "cbs": 1000,
              "pir": 1200,
              "pbs": 1000
            },
            "levels": 1,
            "type": "two-rate-three-color"
          }
        ]
      },
      "control-plane-security": {
        "state": "enable",
        "protocol": [
          {
            "protocol": "PIM",
            "policer": "_DEFAULT_POLICER_PIM",
            "match-tos": 192,
            "match-tc": 120
          }
        ]
      }
    }
  }
}

Secure Control Plane Traffic via Route Lookup

This section describes the configuration to secure the control plane for traffic that is redirected to the CPU via route lookup. Any packet sent to one of the router’s IP addresses ("my IP") and not matching any ACL, will be redirected to the CPU via route lookup. By default this type of traffic is not restricted or rate-limited. In order to secure the control plane, you need to apply ACLs by configuration. Please note you do not need to consider and allow any protocol traffic that is already captured by the automatically created protocol ACLs. You only need to explicitly define rules for any other traffic sent to "my IP". In the simplest case, you can deny any other traffic sent to the router. Typically you will want to allow some additional traffic like ICMP, and deny anything else.

Configuring ACLs

This section describes how to configure ACLs to secure the control plane to protect "my IP". In RFBS, ACLs are applied globally, that is, you do not need to attach them by configuration. Besides, for ACLs matching traffic sent to one of the router’s IP addresses, the redirect-to-cpu action applies implicitly and does not need to be configured.

Syntax:

set forwarding-options acl <options>

Option Description

l3v4

ACL configuration for IPv4

l3v6

ACL configuration for IPv6

rule <rule-name>

Name of the ACL rule

ordinal <ordinal-value>

Number of the configuration entry. Please note the order of the configuration entries (ordinals) does not determine the processing.

match <condition>

Supported match conditions are IP source/destination prefix, prefix lists, source/destination Port, IP protocol, and direction.

action <action>

Supported actions are permit, drop, and police.

priority <value>

ACL entry priority. Determines the processing precedence for multiple matching i.e. conflicting rules. A less-specific rule should have a lower priority so that a more-specific rules takes precedence. Default: 10.

Example 1: Denying any Traffic destined to the Router’s Loopback Addresses

supervisor@rtbrick>LEAF01: cfg> show config forwarding-options acl
{
    "rtbrick-config:acl": {
      "l3v4": {
        "rule": [
          {
            "rule-name": "BLOCK_LOOPBACK_TRAFFIC_v4",
            "ordinal": [
              {
                "ordinal-value": 20,
                "match": {
                  "destination-ipv4-prefix": "198.51.100.43/24",
                  "direction": "ingress"
                },
                "action": {
                  "drop": "true"
                },
                "priority": 20
              }
            ]
          }
        ]
      },
      "l3v6": {
        "rule": [
          {
            "rule-name": "BLOCK_LOOPBACK_TRAFFIC_v6",
            "ordinal": [
              {
                "ordinal-value": 20,
                "match": {
                  "destination-ipv6-prefix": "2001:db8:0:10::/32",
                  "direction": "ingress"
                },
                "action": {
                  "drop": "true"
                },
                "priority": 20
              }
            ]
          }
        ]
      }
    }
  }
supervisor@rtbrick>LEAF01: cfg>

Example 2: ACL allowing and rate-limiting ICMPv4/v6, and denying any other Traffic

supervisor@rtbrick>LEAF01: cfg> show config forwarding-options acl
{
    "rtbrick-config:acl": {
      "l3v4": {
        "rule": [
          {
            "rule-name": "BLOCK_LOOPBACK_TRAFFIC_v4",
            "ordinal": [
              {
                "ordinal-value": 20,
                "match": {
                  "destination-ipv4-prefix": "198.51.100.43/24",
                  "direction": "ingress",
                  "ip-protocol": "ICMP"
                },
                "action": {
                  "permit": "true"
                },
                "priority": 20
              }
            ]
          }
        ]
      },
      "l3v6": {
        "rule": [
          {
            "rule-name": "BLOCK_LOOPBACK_TRAFFIC_v6",
            "ordinal": [
              {
                "ordinal-value": 20,
                "match": {
                  "destination-ipv6-prefix": "2001:db8:0:10::/32",
                  "direction": "ingress",
                  "ip-protocol": "IPv6_ICMP"
                },
                "action": {
                  "permit": "true"
                },
                "priority": 20
              }
            ]
          }
        ]
      }
    }
  }