He everyone! I'm Markus, the author of this blog post and the related USENIX paper. It's great to see the interest in this line of research. I would like to address some of the points brought up in the comments and provide additional information:

- Path-aware Internet architectures and SCION in particular are not source-routing architectures. End hosts neither have/need a full view of the network topology, nor can they unilaterally choose paths. Instead, network operators explore and distribute candidate paths. End hosts get a set of such pre-selected paths from which they can then choose the one they want to use. This is one of the main points of the paper: How can autonomous systems in the Internet efficiently restrict the choices of end hosts. - SCION does not help with censorship. On the contrary: compared to the BGP/IP Internet, some power is shifted from network operators to end hosts. It is these end hosts, who can implement "geo-fencing" not the network operators. While these still retain a significant amount of control over paths (see above) it is easier for end hosts to circumvent networks that employ censorship. - One important point about SCION and other path-aware architectures is that the path control of end hosts is at an autonomous-system level. Thus, most problems with LSRR/SSRR are not present in SCION. For example: - End hosts cannot choose paths at a router level and thus not evade firewalls (unless they are very poorly deployed). - End hosts do not learn any information about the intra-domain topology, only about the inter-domain topology. This information can already be inferred today and is available in public datasets such as the CAIDA AS-relationship dataset [1] - There is a Tor-like anonymous-communication network designed to use with SCION: HORNET [2].

Of course, path control by itself cannot solve all problems. This is why SCION includes several additional innovations such as a public-key infrastructure (PKI) that does not depend on global trust anchors and single points of failure, a secure routing mechanism, highly efficient mechanisms for packet authentication, etc.

[1] https://www.caida.org/data/as-relationships/index.xml [2] https://netsec.ethz.ch/research/anonymity.php

user:	mlegner
created:	November 29, 2020
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