Configuring BGP to Block Denial-of-Service Attacks
RFC 3882
Document | Type |
RFC - Informational
(October 2004; No errata)
Was draft-turk-bgp-dos (rtg)
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Author | Doughan Turk | ||
Last updated | 2015-10-14 | ||
Stream | ISE | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | ISE state | (None) | |
Consensus Boilerplate | Unknown | ||
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3882 (Informational) | |
Telechat date | |||
Responsible AD | Alex Zinin | ||
Send notices to | (None) |
Network Working Group D. Turk Request for Comments: 3882 Bell Canada Category: Informational September 2004 Configuring BGP to Block Denial-of-Service Attacks Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document describes an operational technique that uses BGP communities to remotely trigger black-holing of a particular destination network to block denial-of-service attacks. Black-holing can be applied on a selection of routers rather than all BGP-speaking routers in the network. The document also describes a sinkhole tunnel technique using BGP communities and tunnels to pull traffic into a sinkhole router for analysis. Table of Contents 1. Existing BGP-Triggered Black holing Techniques . . . . . . . . 2 2. Enhanced BGP-Triggered Black holing Technique. . . . . . . . . 3 3. Sinkhole Tunnels . . . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations. . . . . . . . . . . . . . . . . . . . 7 5. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 7 6. Informative References . . . . . . . . . . . . . . . . . . . . 7 7. Author's Addresses . . . . . . . . . . . . . . . . . . . . . . 7 8. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 8 Turk Informational [Page 1] RFC 3882 Configuring BGP to Block DoS Attacks September 2004 1. Existing BGP-Triggered Black-holing Techniques Current BGP-triggered black-holing techniques rely on altering the BGP next hop address of a network targeted by an attack throughout the iBGP network. A customized iBGP advertisement is generated from a router participating in the destination/attacked AS where the next hop address for the targeted network or host is modified to point to an RFC 1918 [RFC1918] (private internet) address. Most routers on the Internet, especially edge routers, have static routes pointing RFC 1918 addresses to the null interface. Those static routes drive all traffic destined to the network under attack to the null interface. When an iBGP-speaking router inside the destination AS receives the iBGP update, the advertised prefix will be added to the routing table with a next hop of one of the networks listed in RFC 1918. The router will then attempt to resolve the RFC 1918 next-hop in order to qualify the route and derive a forwarding interface. This process will return a valid next hop as the null interface. Assuming the router is properly configured to direct RFC 1918 destined traffic to a null interface, traffic destined to the attacked network gets dropped, making the attacked network unreachable to the attacker and everyone else. While this technique shields the internal infrastructure from the attack, protecting a large number of devices, it has the undesirable side effect of rendering the targeted/attacked network unreachable throughout the entire destination AS. Even if a static route pointing an RFC 1918 address to a null interface is not configured on all routers within the destination AS, the modified next hop makes the traffic un-routable to its legitimate destination. Network operators usually use the BGP-triggered black holes for a short period of time. The technique causes traffic drops on all ingress points of the AS for traffic destined to the attacked network. By default, routers dropping traffic into a null interface should send an "ICMP unreachable" message to the source address belonging to the origin/attacking AS. Once the procedure reaches this point, one of the source addresses of the attack traffic is hijacked by introducing a device with the same source IP address into the BGP domain of the destination/attacked AS. The device hijacking the source address collects the ICMP unreachable packets. The source addresses of these ICMP unreachable packets reveal which edge routers within the destination/attacked AS the attack is coming from. The network operator may then opt to manually stop the traffic on the routers from which attack traffic is entering. Turk Informational [Page 2] RFC 3882 Configuring BGP to Block DoS Attacks September 2004 2. Enhanced BGP-Triggered Black-holing Technique This paper describes a technique developed to instruct a selected set of routers to alter the next hop address of a particular prefix by use of the BGP protocol. The next hop can either be a null interface or, as discussed later on in this paper, a sinkhole tunnel interface.Show full document text