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[[meta title="Documentation"]]
-# Monkeysphere Documentation #
-[[toc ]]
-
## Dependencies ##
Monkeysphere relies on:
* [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/)
-## 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.
-
-While ultimately contributing a patch to
-[OpenSSH](http://openssh.com/) (or any
-[free](http://www.chiark.greenend.org.uk/~sgtatham/putty/)
-[SSH](http://www.lysator.liu.se/~nisse/lsh/)
-[implementation](http://matt.ucc.asn.au/dropbear/dropbear.html)) is
-not a bad thing, we hope to be able to better establish the use of a
-PKI without resorting to source modification.
-
-### 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 old; it doesn't appear to have been maintained beyond
- OpenSSH 3.6p1. As of this writing, OpenSSH 5.1p1 is current.
-
- * 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!)
- <ssh@foo.example.net>`) 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](http://tools.ietf.org/html/rfc4880#section-5.2.3.21)
- on the host keys. This means that it could accept a "sign-only"
- key as suitable for authenticating a host, despite the
- clearly-marked intentions of the key-holder.
-
-### 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 newly-seen 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 tactic is quite useful, but doesn't take the system as far as it
-could go, and doesn't tie into any 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 doesn't provide any mechanism for key rotation or revocation:
- Perspectives won't help you if you need to re-key your machine.
-
-### 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).
-
-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.
-
- * X.509 certificates can identify hosts by name, but not by
- individual service. This means that a compromised web or e-mail
- server with access to the X.509 key for that service could re-use
- its certificate as an SSH server, and it would be able to
- masquerade successfully.
+## Other ##
- 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/),
- so they are not by-default shared across services on the same host
- (you can still share a key across services on the same host if you
- like, but the service User IDs can be certified independently of
- one another).
+ * [Similar Projects](/similar)
--- /dev/null
+[[!template id="nav"]]
+[[meta title="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.
+
+While ultimately contributing a patch to
+[OpenSSH](http://openssh.com/) (or any
+[free](http://www.chiark.greenend.org.uk/~sgtatham/putty/)
+[SSH](http://www.lysator.liu.se/~nisse/lsh/)
+[implementation](http://matt.ucc.asn.au/dropbear/dropbear.html)) is
+not a bad thing, we hope to be able to better establish the use of a
+PKI without resorting to source modification.
+
+## 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 old; it doesn't appear to have been maintained beyond
+ OpenSSH 3.6p1. As of this writing, OpenSSH 5.1p1 is current.
+
+ * 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!)
+ <ssh@foo.example.net>`) 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](http://tools.ietf.org/html/rfc4880#section-5.2.3.21)
+ on the host keys. This means that it could accept a "sign-only"
+ key as suitable for authenticating a host, despite the
+ clearly-marked intentions of the key-holder.
+
+## 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 newly-seen 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 tactic is quite useful, but doesn't take the system as far as it
+could go, and doesn't tie into any 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 doesn't provide any mechanism for key rotation or revocation:
+ Perspectives won't help you if you need to re-key your machine.
+
+## 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).
+
+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.
+
+ * X.509 certificates can identify hosts by name, but not by
+ individual service. This means that a compromised web or e-mail
+ server with access to the X.509 key for that service could re-use
+ its certificate as an SSH server, and it would be able to
+ masquerade successfully.
+
+ 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/),
+ so they are not by-default shared across services on the same host
+ (you can still share a key across services on the same host if you
+ like, but the service User IDs can be certified independently of
+ one another).
projects / monkeysphere.git / commitdiff