The routes from the two IGP domains are redistributed to each other.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17816	NET0986	SV-19299r1_rule		Medium

Description
If the gateway router is not a dedicated device for the OOBM network, several safeguards must be implemented for containment of management and production traffic boundaries. Since the managed network and the management network are separate routing domains, separate IGP routing instances must be configured on the router—one for the managed network and one for the OOBM network. In addition, the routes from the two domains must not be redistributed to each other.

Description

If the gateway router is not a dedicated device for the OOBM network, several safeguards must be implemented for containment of management and production traffic boundaries. Since the managed network and the management network are separate routing domains, separate IGP routing instances must be configured on the router—one for the managed network and one for the OOBM network. In addition, the routes from the two domains must not be redistributed to each other.

STIG	Date
Perimeter L3 Switch Security Technical Implementation Guide - Cisco	2018-08-22

Details

Check Text ( C-20200r1_chk )
Verify that the IGP instance used for the managed network does not redistribute routes into the IGP instance used for the management network and vice versa. Route advertisements between two the two routing domains such as OSPF and EIGRP can only be shared via redistribution. Verify that there are no redistribute commands configured under IGP domain for the management network that would enable distributing routes from the IGP domain of the managed network, or vice-versa. The following would be an example of redistributing routes from EIGRP into OSPF. router ospf 1 network 172.20.0.0 redistribute eigrp 12 IOS supports multiple instances of OSPF and EIGRP that are configured using a different process ID. Each EIGRP or OSPF process will run only on the interfaces of the networks specified. Each EIGRP process maintains a separate topology database; likewise, each OSPF process maintains a separate link-state database. Route advertisements between two processes can only be shared via redistribution. Verify that there are no redistribution commands that would distribute routes from the IGP routing domain for the management network into the IGP routing domain of the managed network, or vice-versa. The following would be an example of redistributing routes from one EIGRP into another EIGRP. ! router eigrp 15 network 172.20.0.0 ! router eigrp 10 network 10.0.0.0 redistribute eigrp 15 As an alternative, static routes can be used to forward management traffic to the OOBM interface; however, this method may not scale well. If static routes are used to forward management traffic to the OOB backbone network, verify that the OOBM interface is not an IGP adjacency and that the correct destination prefix has been configured to forward the management traffic to the correct next-hop and interface for the static route. In the following configuration examples, 10.1.1.0/24 is the management network and 10.1.20.4 is the interface address of the OOB backbone router that the OOB gateway router connects to. The network 10.1.20.0/24 is the OOBM backbone. interface Serial0/0 description to_OOBM_Backbone ip address 10.1.20.3 255.255.255.0 interface Fastethernet 0/0 description to_our_PrivateNet ip address 172.20.4.2 255.255.255.0 interface Fastethernet 0/1 description to_our_ServiceNet ip address 172.20.5.2 255.255.255.0 ! router ospf 1 network 172.20.0.0 ! ip route 10.1.1.0 255.255.255.0 10.1.20.4 Serial0/0

Check Text ( C-20200r1_chk )

Verify that the IGP instance used for the managed network does not redistribute routes into the IGP instance used for the management network and vice versa.

Route advertisements between two the two routing domains such as OSPF and EIGRP can only be shared via redistribution. Verify that there are no redistribute commands configured under IGP domain for the management network that would enable distributing routes from the IGP domain of the managed network, or vice-versa. The following would be an example of redistributing routes from EIGRP into OSPF.

router ospf 1
network 172.20.0.0
redistribute eigrp 12

IOS supports multiple instances of OSPF and EIGRP that are configured using a different process ID. Each EIGRP or OSPF process will run only on the interfaces of the networks specified. Each EIGRP process maintains a separate topology database; likewise, each OSPF process maintains a separate link-state database. Route advertisements between two processes can only be shared via redistribution. Verify that there are no redistribution commands that would distribute routes from the IGP routing domain for the management network into the IGP routing domain of the managed network, or vice-versa. The following would be an example of redistributing routes from one EIGRP into another EIGRP.
!
router eigrp 15
network 172.20.0.0
!
router eigrp 10
network 10.0.0.0
redistribute eigrp 15

As an alternative, static routes can be used to forward management traffic to the OOBM interface; however, this method may not scale well.

If static routes are used to forward management traffic to the OOB backbone network, verify that the OOBM interface is not an IGP adjacency and that the correct destination prefix has been configured to forward the management traffic to the correct next-hop and interface for the static route. In the following configuration examples, 10.1.1.0/24 is the management network and 10.1.20.4 is the interface address of the OOB backbone router that the OOB gateway router connects to. The network 10.1.20.0/24 is the OOBM backbone.

interface Serial0/0
description to_OOBM_Backbone
ip address 10.1.20.3 255.255.255.0
interface Fastethernet 0/0
description to_our_PrivateNet
ip address 172.20.4.2 255.255.255.0
interface Fastethernet 0/1
description to_our_ServiceNet
ip address 172.20.5.2 255.255.255.0
!
router ospf 1
network 172.20.0.0
!
ip route 10.1.1.0 255.255.255.0 10.1.20.4 Serial0/0

Fix Text (F-17731r1_fix)
Ensure that the IGP instance used for the managed network does not redistribute routes into the IGP instance used for the management network and vice versa.