One great new feature of the 0.2.5.x branch is support for Linux seccomp. There is a similar project that's cross-platform (FreeBSD, DragonFly BSD, Linux for now) called Capsicum.

It is a project supported by University of Cambridge Computer Laboratory, grants from Google, the FreeBSD Foundation and DARPA. Its goals are similar to seccomp, but the Capsicum project utilizes approaches quite different from how seccomp does things, potentially preventing a different set of attacks.

While the FreeBSD implementation is the furthest so far with Linux development still not being in mainline yet there are a number of applications (ping, tcpdump, gzip, Chromium (wip)) already supporting Capsicum. According to a presentation of the project adding support for Capsicum tends to be easier, than for adding seccomp support.

Is anyone working on this right now? Are there any plans on supporting it? And most importantly is there any reason to not support it?

  • 1
    i would suggest taking this to [tor-dev] - you're a lot more likely to get appropriate answers there. if i'm not mistaken, this is the web equivalent of [tor-talk] for usage questions ...
    – mroq
    Commented Nov 6, 2014 at 15:20
  • 1
    @mroq Dev questions are welcome here too (but I don't disagree, you're more likely to get a good answer on [tor-dev]).
    – user5
    Commented Nov 6, 2014 at 20:52

1 Answer 1


As far as I am aware (and I may be mistaken):

  • There is no one working on it right now.
  • There are no plans for anyone working on it in the near future.
  • There is no reason not to support it.

It comes down to a matter of "all the official developers are really busy with other projects", the big one being a fairly major hidden service revamp. That said, the seccomp support was a Google Summer of Code project, and there is nothing stopping an enterprising developer from adding Capcicum support and submitting patches for review and eventual merging.

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