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Yehuda Afek, Tel-Aviv University / WANWall Ltd. Anat Bremler-Barr, Alon Golan, Hank Nussbacher, Dan Touitou WANWall Ltd. Diversion & Sieving Techniques to Defeat DDoS. DDoS protection, Where & How?. R4. R5. peering. R2. R3. 1000. 1000. R1. 100. R. R. R. FE. Server1. Victim.
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Yehuda Afek, Tel-Aviv University / WANWall Ltd.Anat Bremler-Barr, Alon Golan, Hank Nussbacher, Dan Touitou WANWall Ltd. Diversion & Sieving Techniques to Defeat DDoS
. . . . . . . . DDoS protection, Where & How? R4 R5 peering R2 R3 1000 1000 R1 100 R R R FE Server1 Victim Server2
1 ACLs, CARs, null/rt. . . . . . . . . At the Routers R4 R5 peering R2 R3 • Rand. Spoofing • Throws good with bad • Router degradation 1000 1000 R1 100 R R R FE Server1 Victim Server2
2 . . . . . . . . At the Edge R4 R5 peering R2 R3 • Chocked • Point of failure • Not scalable 1000 1000 R1 100 R R R FE Server1 Victim Server2
3 . . . . . . . . At the Back Bone R4 R5 peering R2 R3 • Throughput • Point of failure • All suffer 1000 1000 R1 100 R R R FE Server1 Victim Server2
4 4 . . . . . . . . Diversion R4 R5 peering R2 R3 • Not on critical path • Router route • Upstream • Sharing • Dynamic 1000 1000 R1 100 R R R FE Server1 Victim Server2
Basic Scheme AS 56 ISP Backbone PR AS 24 Victim
Basic Concepts Divert victim’s traffic Sieve Legitimate traffic continues on its route Victim traffic R Victim clean traffic Malicious packets Database
2 1 Victim Operational process N O C AS x
Sieving Malicious traffic Output Anti spoofing Learning & Statistical analysis HTTP Analysis & Authentication Packet filtering
Sieving techniques Filters: IP's, ports, flags, etc. Anti-spoofing: • TCP • Other Recognition: • Statistical Analysis • Layers 3-7 High-level Protocols: • HTTP specific (recognize anomalous behavior) • Other
Diversion • Divert • Return good traffic Without looping ! Victim traffic R Victim clean traffic Malicious packets Database
Diversion: BGP + next L3 • Divert: BGP announce a /32 from the box no_export and no_advertise community • Return: Next layer 3 device R Victim traffic L2 device Victim clean traffic L3 Malicious packets
Diversion: BGP + GRE • Divert: BGP • Return: GRE GRE de-cap increases VIP load < 20% [Wessels & Hardie, NANOG19, Albuquerque] BGP Victim traffic R GRE Victim clean traffic R Malicious packets
Phase 2: Attack + Normal traffic Phase 2: Attack + Normal traffic Phase 3: Attack + Normal traffic + Diversion Diversion test A A C Phase 1: Normal traffic X Gig R Gig W X 100BT R I V victim Non-victim
Diversion effect Attack + diversion Attack normal usec
Diversion WCCP v2 Web Cache Coordination Protocol v2 [IETF internet draft draft-wilson-wrec-wccp-v2-00.txt] • remote diversion • Protocol, no dynamic config. Current Status Available on 6500, 7200, 7500, 7600SR, from IOS 12.0(3)T and 12.0(11)S with dCEF Other vendors? Victim traffic R WCCP Victim clean traffic Malicious packets
Diversion PBR / FBF • Divert: Policy Based Routing Filter Based Forwarding • Return: Normal Route Table PBR Victim traffic R Victim clean traffic Malicious packets
Diversion: BGP + PBR • Divert: BGP • Return: PBR guard’s Interface card BGP Victim traffic R PBR Victim clean traffic Malicious packets
PBR Dynamic configuration • adding access list on demand CPU load: • VIP or RSP CPU load • Juniper FBF dedicated processor, Internet proc II (from JunOS 4.4) Victim traffic R PBR Victim clean traffic Malicious packets
PBR Warts 12.1(8a)E4 and 12.0(18)S and 12.2(2)T with “distributed cef” will not PBR properly! BUG ID: cscdp78100 • all packets diverted - rather than what is matched • but “ip cef” works properly • tested on 7513 on FE as well as GE (GEIP+) ip access-list extended WW33 permit ip any victim-ipvictim-mask route-map WWMap permit 33 match ip address WW33 set ip next-hop Guard-guard-IP end interface GigabitEthernet0/0/0 ip policy route-map WWMap
Diversion Double Addressing • Divert: BGP • Return: Double addressing victim with private IP address, routed only internally BGP Victim traffic R Victim clean traffic Malicious packets
Double Addressing PR NAT AS Data Center Victim
Reverse Protection AS y Victim AS x
AS x Flash Crowd Reverse Proxy [Wessels & Hardie; Surrogate NANOG19]
Diversion for DDoS Summary • Maximize goodput to victim • Leave data path free • Let routers route • Protect any device • Sharing a large resouce on demand • Upstream (ala push back)
