X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=website%2Fdoc.mdwn;h=3464455f45820a8394618177888c72c048867483;hb=8bba6f27dd299180bd55d9f27b8d1b219c356095;hp=33fe340b84ffcac4383ae11911be846a115ebc8f;hpb=4ac01c98191fd4d6d0ab3654de427fa02f0e93f7;p=monkeysphere.git diff --git a/website/doc.mdwn b/website/doc.mdwn index 33fe340..3464455 100644 --- a/website/doc.mdwn +++ b/website/doc.mdwn @@ -1,12 +1,123 @@ +[[!template id="nav"]] + # Monkeysphere Documentation # + ## Dependencies ## * Monkeysphere relies on [GnuTLS](http://gnutls.org/) version 2.4.0 or later. +## Getting started ## + + * Getting started as a [user](/getting-started-user) + * Getting started as a [server admin](/getting-started-admin) + ## References ## * [Initial specifications at CMRG](http://cmrg.fifthhorseman.net/wiki/OpenPGPandSSH) * [OpenPGP (RFC 4880)](http://tools.ietf.org/html/rfc4880) * [Secure Shell Authentication Protocol (RFC 4252)](http://tools.ietf.org/html/rfc4252) -* [URI scheme for SSH, RFC draft](http://tools.ietf.org/wg/secsh/draft-ietf-secsh-scp-sftp-ssh-uri/) + * [URI scheme for SSH, RFC draft](http://tools.ietf.org/wg/secsh/draft-ietf-secsh-scp-sftp-ssh-uri/) + +## Similar Projects ## + +The monkeysphere isn't the only project intending to implement a PKI +for OpenSSH. We provide links to these other projects because they're +interesting, though we have concerns with their approaches. + +All of the other projects we've found so far require a patched version +of OpenSSH, which makes adoption more difficult. Most people don't +build their own software, and simply overlaying a patched binary is +associated with significant maintenance (and therefore security) +problems. A PKI becomes more useful the more people participate in +it, so widespread adoption is important. + +### `openssh-gpg` ### + +[openssh-gpg](http://www.red-bean.com/~nemo/openssh-gpg/) is a patch +against OpenSSH to support OpenPGP certificates. According to its +documentation, it is intended to support [`pgp-sign-rsa` and +`pgp-sign-dss` public key algorithms for hosts, as specified by the +IETF](http://tools.ietf.org/html/rfc4253#section-6.6). + +Some concerns with `openssh-gpg`: + + * This patch is significantly old; it doesn't appear to have been + maintained beyond OpenSSH 3.6p1. As of this writing, OpenSSH is on + version 5.1p1. + + * It only provides infrastructure in one direction: the user + authenticating the host by name. There doesn't seem to be a + mechanism for dealing with identifying users by name, or allowing + users to globally revoke or update keys. + + * The choice of User ID (`anything goes here (and here!) + `) for host keys overlaps with the current use + of the User ID space. While it's unlikely that someone actually + uses this e-mail address in the web of trust, it would be a nasty + collision, as the holder of that key could impersonate the server + in question. The monkeysphere uses [User IDs of the form + `ssh://foo.example.net`](http://tools.ietf.org/wg/secsh/draft-ietf-secsh-scp-sftp-ssh-uri/) + to avoid collisions with existing use. + + * It's not clear that `openssh-gpg` acknowledges or respects the + usage flags on the host keys. + + * It requires patching OpenSSH. + + +### Perspectives OpenSSH client ### + +[The Perspectives project](http://www.cs.cmu.edu/~perspectives/) at +CMU has released an [openssh client that uses network +notaries](http://www.cs.cmu.edu/~perspectives/openssh.html) to bolster +your confidence in new keys. This offers a defense against a narrow +MITM attack (e.g. by someone who controls your local gateway) by +simply verifying that other machines from around the network see the +same keys for the remote host that you're seeing. + +This is quite useful, but doesn't take the system as far as it could +go, and doesn't tie into the existing web of trust. + +Some concerns with the Perspectives OpenSSH client: + + * This client won't help if you are connecting to machines behind + firewalls, on NAT'ed LANs, with source IP filtering, or otherwise + in a restricted network state. + + * There is still a question of why you should trust these particular + notaries during your verification. Who are the notaries? How + could they be compromised? + + * It only provides infrastructure in one direction: the user + authenticating the host by name. There is no mechanism for dealing + with identifying users by name, or allowing users to globally + revoke or change keys. + + * It requires patching OpenSSH + +### OpenSSH with X.509v3 certificates ### + +Roumen Petrov [maintains a patch to OpenSSH that works with the X.509 +PKI model](http://www.roumenpetrov.info/openssh/). This is the +certificate hierarchy commonly used by TLS (and SSL before that). + +Some concerns about OpenSSH with X.509v3: + + * the X.509 certificate specification itself [encourages corporate + consolidation and centralized global "trust" because of its + single-issuer architectural + limitation](http://lair.fifthhorseman.net/~dkg/tls-centralization/). + This results in an expensive and cumbersome system for smaller + players, and it also doesn't correspond to the true distributed + nature of human-to-human trust. Furthermore, centralized global + "trusted authorities" create a tempting target for attack, and a + single-point-of-failure if an attack is successful. + + Depending on how you declare your trust relationships, OpenPGP is + capable of providing the same hierarchical structure as X.509, but + it is not limited to such a structure. The OpenPGP Web of Trust + model is more flexible and more adaptable to represent real-world + trust than X.509's rigid hierarchy. + + * It requires patching OpenSSH.