Posts Tagged ‘route-map’

Securing MP-EBGP VPNv4 for Inter-AS MPLS VPN

February 21, 2009 4 comments

1. Securing Inter-AS interfaces

  • Permit only BGP traffic because the other traffic that traverse between ASBRs is IP Labelled traffic.
  • Apply inbound and outbound. Logging the denied traffic for further investigation

interface FastEthernet0/0
ip address
ip access-group ASBR-IN in
ip access-group ASBR-OUT out
ip access-list extended ASBR-IN
permit tcp any any eq bgp
permit tcp any eq bgp any
deny ip any any log
ip access-list extended ASBR-OUT
permit tcp any eq bgp any
permit tcp any any eq bgp
deny ip any any log

  • See the example of IPv4 and IP Labelled traffic that traverse beetwen ASBR routers below. Note that IPv4 is only BGP communication, and the remaining traffic is telnet or icmp traffic that has been labelled.


2. Securing MP-EBGP Peering Session

  • Use BGP MD5 Authentication to ensure that the BGP peer is the legitimate neighbor.

neighbor password 7 011A08105E19071C

  • Use BGP TTL-Security with number of hop is 1. The BGP peering session between ASBRs usually using the back-to-back interface.

neighbor ttl-security hops 1

  • Both ASBR did not communicating ini IPv4 (except BGP communication), so we must turn-off the IPv4 BGP Address-family

no bgp default ipv4-unicast

  • Use BGP Dampening to secure the ASBR CPU from frequently flapped routes

bgp dampening

  • Filter the Route-Target. Only allows Route-Target that need to extend across the AS. Disable BGP default RT filter to allow VPNv4 routes installed in the BGP VPNv4 table even the Route-Target is not configured on the ASBR.

Router BGP 100
no bgp default route-target filter
address-family vpnv4
neighbor route-map ASBR in
exit address-family
route-map ASBR permit 10
match extcommunity 101
ip extcommunity-list 101 permit RT:200:123+
ip extcommunity-list 101 permit RT:200:222+

  • Set the BGP maximum-prefix filter.

neighbor maximum-prefix 100 80

3. General Router Security

  • AAA Authentication
  • SSH Access for Management
  • Access-Class for Line VTY access
  • Read-Only SNMP with ACL
  • using NTP and disabling ntp on not appropriate interfaces
  • Enable CoPP if necessary
  • Specific and strict ACL for inter-AS interface
  • Enable Security Services
  1. Service Password-Encryption
  2. Service Timestamp for Debug and Logging
  3. Logging buffered
  • Disable small Services
  1. Disable udp-small-services (echo, discard)
  2. Disable tcp-small-service
  3. Disable finger-service
  4. Disable pad-service
  5. Disable unused bootp service
  6. Disable cdp
  7. Disable icmp unreachables on all interfaces including null0
  8. Disable ip source-route options
  9. Disable proxy-arp per interfaces
  10. Disable directed-broadcast per interfaces
  11. Disable icmp mask-reply per interfaces
  12. Disable http-service
  13. Disable ident-service