BGP over TLS (was: Re: "Using Cloud Resources to Dramatically Improve Internet Routing")

Mon Oct 21 19:37:11 UTC 2019

> On Oct 21, 2019, at 3:25 PM, Brandon Martin <lists.nanog at monmotha.net> wrote:
> 
> On 10/21/19 11:30 AM, Keith Medcalf wrote:
>> Why cannot one just put the MD5 authenticated connection inside a TLS connection?  What is the advantage to be gained by replacing the authentication mechanism with weaker certificate authentication method available with TLS?
> 
> Self-issued certificates with either CA pinning or end-certificate hash pinning is arguably more secure than a shared passphrase as used by TCP-MD5 in that someone with knowledge of the secrets of one end cannot use it to impersonate the other end whereas a shared passphrase is inherently shared and symmetric in that respect.  Whether that really provides much value in the context of a BGP session is perhaps questionable.

Considering a lot of hand-wringing from the various security conscious folk is over the ability to easily re-key, I think it mostly just complicates things.  Certs are effectively a much nicer single use key.  Exactly how the cert lifetime interacts with peering sessions is likely to be several flavors of ugly.

> 
> Wouldn't ipsec be a "cleaner" solution to this (buginess of implementations and difficulty of configuration aside)?  It would also solve the TCP-RST injection issues that TCP-MD5 was intended to resolve.  You can use null encryption with ESP or even just AH if you want authentication without confidentiality, too.  Or are we all going to admit that ipsec is almost dead in that it's just too darned complex?  Just run BGP over TCP as normal and install a security policy that says it must use ipsec with appropriate (agreed-upon) authentication.  "Just", right?

BGP over ipsec works fine.  But that said, it's mostly done with pre-shared keys.

The ugly issue of ipsec is that the ecosystem really wants IKE to do the good things people associate with long lived sessions.  I don't even vaguely pretend to be an ipsec/ike expert, but the wrangling over this and router bootstrapping issues generated a lot of heat and a small amount of light in IETF a while back.

And if you have a rather scaled out router, imagine the cpu melting that goes with a cold startup scenario where you have to get all of those IKE sessions up to start up your BGP.  Now think what that does to your restart time. 

-- Jeff