BGP Origin Authentication and RPKI
June 14, 2012
The Internet is built on a web of trust. As an engineer, it's astonishing that the Internet works reliably or even at all because nothing is guaranteed or certain. Internet security continues to be free and open, but also untrustworthy and insecure.
The most recent initiative to provide assurance for the future of the Internet is BGP Origin Authentication. For every IP network connected to the Internet, a BGP route is announced to your upstream provider and neighbors. In turn, each router then announces these routes to all the other routers across the globe.
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The lesser-known problem is that anyone, anywhere can announce any IP route. There are no controls on what routes can be announced, by whom and where. Thus, if a network administrator decides to use your public IP address space and starts to announce that route to the Internet, there's nothing to prevent it.
There are a significant number of hijacked prefixes. How does this happen ? Let's say a company goes out of business and its /20 route is pulled from the Internet as its Internet service is terminated. At some point, the RIR will reclaim the IP allocation when membership fees aren't renewed. In the meantime, a less scrupulous person may have started to announce the route to the Internet that had been used for hosted services. Today, many spam and darknets are using illegitimate IP addressing in their hosting centers, as are many well-recognized companies where an engineer needs a quick fix.
There is no solution today to theft of IP addressing. For the past five or so years, the nerds in the bowels of the Internet have argued about ways to solve the problem. Most of the debate is arcane and cryptic, but a solution has reached consensus: BGP Origin Authentication is a "good-enough" solution to solving the validation of routes in the Internet.
Each organization that owns a public IP address allocation must be a registered member with a Routing Registry such as RIPE, APNIC or ARIN. Membership also allows an entity to be the owner of an Autonomous System Number (ASN). Both IP addresses and ASN are globally unique identifiers that are intended to prevent duplicate identifiers.
This membership must be renewed regularly with a membership fee (demonstrating commitment). As such, the RIRs are a central point in the Internet routing hierarchy and can act as a certificate authority for issuing cryptographic certificates. So far, scale and security appears probable because there are only five RIRs in the world that don't have a commercial imperative like existing CAs that have failed with SSL certificates.
Each member of the RIR can apply to receive a cryptographic certificate for its IP route and ASN. This certificate is loaded onto the Internet router and included in the routing announcement. The certificate proves that you are the registered owner of the IP Addresses and ASN and, therefore, are the authorized owner of that resource. It's worth noting that BGP supports the addition of new services in this way. Most Internet routers won't support RPKI, but they will transparently pass the data into the wider Internet and this is how gradual adoption of RPKI can be achieved without requiring major changes to the infrastructure.
BGP Origin Authentication is a positive step in enhancing Internet security. As IP addresses and ASN are integral to the Internet and are becoming regarding as corporate property, the need to secure these core functions is vital. While path validation would be a much better solution, BGP Origin Authentication looks like an 80/20--80% of the result for 20% of the effort. The Internet has been a good-enough solution for the last 20 years--wishing for the best might always be out of reach.
You can find more information in a Pocket Pushers podcast recorded recently with Alex White from RIPE and Russ White, during which a detailed discussion was held about the technology, limits and implementation challenges.