-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 | The tor man page says, | | "MinUptimeHidServDirectoryV2 N seconds|minutes|hours|days|weeks | Minimum uptime of a v2 hidden service directory to be accepted | as such by authoritative directories. (Default: 24 hours)" | | My questions are, what is the justification for the default of 24 hours? And | why have this particular option at all? Why not instead have a "no longer | fresh/up to date" indicator somewhere, much like the fresh-until line for | consensus/status documents, so that a server that beomes disconnected or goes | down for only a brief time will remain available to provide hidden service | directory service as much of the time as possible? Or, better yet, why not | simply handle this issue the same way that it is handled for normal directory | (mirror) service?
The default of 24 hours ensures that hidden service directories are available for the next few hours with a certain probability. The idea is that there are hundreds of hidden service directories at some point which are not authoritative any more, but provide a more scalable and robust storage than the three authoritative ones can. Hidden services and clients need to have a view as consistent as possible of which hidden service directories are out there, so that clients can find previously stored hidden service descriptors. The 24 hours have turned out to be a characteristic that allows distinguishing highly available relays from others. The rationale behind it is that a certain number of relay operators turn their relays off over night. The following diagram shows the variation of relays with different minimum uptimes over an interval of 2+ months. You can see the difference between minimum uptimes of 16 hours and lower and those of 20 hours and higher. That is the reason for the default of 24 hours. http://freehaven.net/~karsten/dirnodesminuptime.pdf The option MinUptimeHidServDirectoryV2 is mainly there to perform tests with the distributed hidden service directory without having to wait for 24 hours. It is not required to set it in the public Tor network. (It only has an effect on directory authorities anyway.) I should probably make the design paper of the distributed hidden service directory available rather soon. It answers questions like yours. Hope that helps! - --Karsten -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFImE8S0M+WPffBEmURAseDAJ9zbmc9Fr0u1NDSdfBZCMf3IHxAnwCghAYp ioWjbih5vuaFVbydCthSGu0= =BusG -----END PGP SIGNATURE-----