nanog mailing list archives

Re: CGN fixed/hashed nat question


From: Simon Perreault <simon.perreault () viagenie ca>
Date: Wed, 23 Jan 2013 16:54:45 +0100

Le 2013-01-23 16:37, William Herrin a écrit :
NAT traversal using port prediction is a Worst Current Practice.

In fact, were someone to use those "worst current practices" to build
some generic p2p VPN software, even old games could leverage it to
allow someone behind a CGN to host.

Have a look at this:
http://tools.ietf.org/html/draft-ietf-behave-lsn-requirements

These are the IETF's requirements for CGNs. The intent is to provide guidelines to vendors so that their CGNs can be as harmless as possible.

A CGN that obeys these requirements will allow NAT traversal by virtue of having an Endpoint-Independent Mapping behaviour. That is the BCP. Not port prediction.

Simon


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