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The Cisco perimeter router must be configured to block inbound packets with source Bogon IP address prefixes.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
|---|---|---|---|---|
| V-216755 | CISC-RT-000270 | SV-216755r856441_rule | Medium |
| Description |
|---|
| Packets with Bogon IP source addresses should never be allowed to traverse the IP core. Bogon IP networks are RFC1918 addresses or address blocks that have never been assigned by the IANA or have been reserved. |
| STIG | Date |
|---|---|
| Cisco IOS XR Router RTR Security Technical Implementation Guide | 2023-02-28 |
Details
| Check Text ( C-17987r288654_chk ) |
|---|
| This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that an ingress ACL applied to all external interfaces is blocking packets with Bogon source addresses. Step 1: Verify an ACL has been configured containing the current Bogon prefixes as shown in the example below. ipv4 access-list EXTERNAL_ACL_INBOUND 10 deny ipv4 0.0.0.0 0.255.255.255 any log-input 20 deny ipv4 10.0.0.0 0.255.255.255 any log-input 30 deny ipv4 100.64.0.0 0.63.255.255 any log-input 40 deny ipv4 127.0.0.0 0.255.255.255 any log-input 50 deny ipv4 169.254.0.0 0.0.255.255 any log-input 60 deny ipv4 172.16.0.0 0.15.255.255 any log-input 70 deny ipv4 192.0.0.0 0.0.0.255 any log-input 80 deny ipv4 192.0.2.0 0.0.0.255 any log-input 90 deny ipv4 192.168.0.0 0.0.255.255 any log-input 100 deny ipv4 198.18.0.0 0.1.255.255 any log-input 110 deny ipv4 198.51.100.0 0.0.0.255 any log-input 120 deny ipv4 203.0.113.0 0.0.0.255 any log-input 130 deny ipv4 224.0.0.0 31.255.255.255 any log-input 140 permit tcp any any established 150 permit tcp host x.12.1.9 host x.12.1.10 eq bgp 160 permit tcp host x.12.1.9 eq bgp host x.12.1.10 170 permit icmp host x.12.1.9 host x.12.1.10 echo 180 permit icmp host x.12.1.9 host x.12.1.10 echo-reply … … … 260 deny ipv4 any any log-input External Interfaces connected to the NIPRNet or SIPRNet Review the inbound ACLs on external facing interfaces attached to the NIPRNet or SIPRNet to validate access control lists are configured to block inbound packets with IP sources addresses as documented in RFC5735 and RFC6598. External Interfaces connected to a commercial ISP or other non-DoD network Review the inbound ACLs on external facing interfaces validate access control lists are configured to block inbound packets with IP sources addresses as documented in RFC5735 and RFC6598 as well as address space that has been allocated to the RIRs but not assigned by the RIR to an ISP or other enterprise network. The full list of bogons can be found at the following link: www.team-cymru.org/Services/Bogons/fullbogons-ipv4.txt Step 2: Verify that the inbound ACL applied to all external interfaces will block all traffic from Bogon source addresses. interface GigabitEthernet0/0/0/1 ipv4 address x.12.1.10 255.255.255.2 ipv4 access-group EXTERNAL_ACL_INBOUND ingress If the router is not configured to block inbound packets with source Bogon IP addresses, this is a finding. |
| Fix Text (F-17985r288655_fix) |
|---|
| This requirement is not applicable for the DODIN Backbone. Configure the perimeter to block inbound packets with Bogon source addresses. Step 1: Configure an ACL containing the current Bogon prefixes as shown below. RP/0/0/CPU0:R2(config)#ipv4 access-list EXTERNAL_ACL_INBOUND RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 0.0.0.0 0.255.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 10.0.0.0 0.255.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 100.64.0.0 0.63.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 127.0.0.0 0.255.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 169.254.0.0 0.0.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 172.16.0.0 0.15.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 192.0.0.0 0.0.0.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 192.0.2.0 0.0.0.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 192.168.0.0 0.0.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 198.18.0.0 0.1.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 198.51.100.0 0.0.0.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 203.0.113.0 0.0.0.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip 224.0.0.0 31.255.255.255 any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#permit tcp any any established RP/0/0/CPU0:R2(config-ipv4-acl)#permit tcp host x.12.1.9 host x.12.1.10 eq bgp RP/0/0/CPU0:R2(config-ipv4-acl)#permit tcp host x.12.1.9 eq bgp host x.12.1.10 RP/0/0/CPU0:R2(config-ipv4-acl)#permit icmp host x.12.1.9 host x.12.1.10 echo RP/0/0/CPU0:R2(config-ipv4-acl)#permit icmp host x.12.1.9 host x.12.1.10 echo-reply … … … RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip any any log-input RP/0/0/CPU0:R2(config-ipv4-acl)#end Step 2: Apply the ACL inbound on all external interfaces. RP/0/0/CPU0:R3(config)#int g0/0/0/1 RP/0/0/CPU0:R3(config-if)#ipv4 access-group EXTERNAL_ACL_INBOUND in RP/0/0/CPU0:R3(config-if)#end |