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The Cisco perimeter switch must be configured to enforce approved authorizations for controlling the flow of information between interconnected networks in accordance with applicable policy.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
|---|---|---|---|---|
| V-101891 | CISC-RT-000250 | SV-110995r1_rule | Medium |
| Description |
|---|
| Information flow control regulates authorized information to travel within a network and between interconnected networks. Controlling the flow of network traffic is critical so it does not introduce any unacceptable risk to the network infrastructure or data. An example of a flow control restriction is blocking outside traffic claiming to be from within the organization. For most switches, internal information flow control is a product of system design. |
| STIG | Date |
|---|---|
| Cisco NX-OS Switch RTR Security Technical Implementation Guide | 2020-05-20 |
Details
| Check Text ( C-100779r1_chk ) |
|---|
| Review the switch configuration to verify that ACLs are configured to allow or deny traffic for specific destination addresses as well as ports and protocols. In the example below, the switch is peering BGP with DISN. ICMP echo and echo-reply packets are allowed for troubleshooting connectivity. WWW traffic is permitted inbound to the NIPRNet host-facing web server (x.11.2.3). Step 1: Verify that an inbound ACL is applied to all external interfaces as shown in the example below: interface Ethernet2/2 description link to DISN no switchport ip access-group EXTERNAL_ACL in ip address x.11.1.2 255.255.255.254 Step 2: Review inbound ACL to verify that it is configured to deny all other traffic that is not explicitly allowed. ip access-list EXTERNAL_ACL 10 permit tcp any any established 20 permit tcp x.11.1.1/32 eq bgp x.11.1.2/32 30 permit tcp x.11.1.1/32 x.11.1.2/32 eq bgp 40 permit icmp x.11.1.1/32 x.11.1.2/32 echo 50 permit icmp x.11.1.1/32 x.11.1.2/32 echo-reply 60 permit tcp any x.11.2.3/32 eq www 70 permit … … … … 90 deny ip any any log If the switch is not configured to enforce approved authorizations for controlling the flow of information between interconnected networks, this is a finding. |
| Fix Text (F-107573r1_fix) |
|---|
| Step 1: Configure an ACL to allow or deny traffic as shown in the example below: SW2(config)# ip access-list EXTERNAL_ACL SW2(config-acl)# permit tcp any any established SW2(config-acl)# permit tcp x.11.1.1/32 eq bgp x.11.1.2/32 SW2(config-acl)# permit tcp x.11.1.1/32 x.11.1.2/32 eq bgp SW2(config-acl)# permit icmp x.11.1.1/32 x.11.1.2/32 echo SW2(config-acl)# permit icmp x.11.1.1/32 x.11.1.2/32 echo-reply SW2(config-acl)# permit tcp any x.11.2.3/32 eq www SW2(config-acl)# deny ip any any log SW2(config-acl)# exit Step 2: Apply the ACL inbound on all applicable interfaces. SW1(config)#int e2/2 SW1(config-if)# ip access-group EXTERNAL_ACL in |