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CISC-RT-000270 - The Cisco perimeter router must be configured to block inbound packets with source Bogon IP address prefixes.

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Information

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.

Solution

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

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XR_Router_Y24M07_STIG.zip

Item Details

References: CAT|II, CCI|CCI-002403, Rule-ID|SV-216755r856441_rule, STIG-ID|CISC-RT-000270, STIG-Legacy|SV-105855, STIG-Legacy|V-96717, Vuln-ID|V-216755

Plugin: Cisco

Control ID: 7aa34b0833ea3d52fb30e8b0eb0233975cd2424e36aef138353824b68b25a9b7