Monkeysphere User README ======================== You don't have to be an OpenSSH or OpenPGP expert to use the Monkeysphere. However, you should be comfortable using secure shell (ssh), and you should already have GnuPG installed and an OpenPGP key pair before you begin. As a regular user on a system where the monkeysphere package is installed, you probably want to do a few things: Keep your keyring up-to-date ---------------------------- Regularly refresh your GnuPG keyring from the keyservers. This can be done with a simple cronjob. An example of crontab line to do this is: 0 12 * * * /usr/bin/gpg --refresh-keys > /dev/null 2>&1 This would refresh your keychain every day at noon. Keeping your `known_hosts` file in sync with your keyring ----------------------------------------------------------- With your keyring updated, you want to make sure that OpenSSH can still see the most recent trusted information about who the various hosts are. This can be done with the monkeysphere-ssh-proxycommand (see next section) or with the `update-known_hosts` command: $ monkeysphere update-known_hosts This command will check to see if there is an OpenPGP key for each (non-hashed) host listed in the `known_hosts` file, and then add the key for that host to the `known_hosts` file if one is found. This command could be added to a crontab as well, if desired. Using `monkeysphere-ssh-proxycommand`(1) ---------------------------------------- The best way to handle host keys is to use the monkeysphere ssh proxy command. This command will make sure the `known_hosts` file is up-to-date for the host you are connecting to with ssh. The best way to integrate this is to add the following line to the "Host *" section of your `~/.ssh/config` file: ProxyCommand monkeysphere-ssh-proxycommand %h %p The "Host *" section specifies what ssh options to use for all connections. If you don't already have a "Host *" line, you can add it by entering: Host * On a line by itself. Add the ProxyCommand line just below it. Once you've completed this step - you are half-way there. You will now be able to verify servers participating in the monkeysphere provided their keys have been signed by someone that you trust. FIXME: We should setup a way for someone to download a test gpg key and then connect to a test server that is signed by this gpg key so users can establish that they are setup correctly. The remaining steps will complete the second half: allowing servers to verify you based on your OpenPGP key. Setting up an OpenPGP authentication key ---------------------------------------- First things first: you'll need to create an "authentication" subkey for your current key, if you don't already have one. If you already have a GPG key, you can add an authentication subkey with: $ monkeysphere gen-subkey If you have more than one secret key, you'll need to specify the key you want to add the subkey to on the command line. Using your OpenPGP authentication key for SSH --------------------------------------------- Once you have created an OpenPGP authentication subkey, you will need to feed it to your ssh agent. Currently (2008-08-23), gnutls does not support this operation. In order to take this step, you will need to upgrade to a patched version of gnutls. You can easily upgrade a Debian system by adding the following to `/etc/apt/sources.list.d/monkeysphere.list`: deb http://archive.monkeysphere.info/debian experimental gnutls deb-src http://archive.monkeysphere.info/debian experimental gnutls Next, run `aptitude update; aptitude install libgnutls26`. With the patched gnutls installed, you can feed your authentication subkey to your ssh agent by running: $ monkeysphere subkey-to-ssh-agent FIXME: using the key with a single ssh connection? Establish trust --------------- Now that you have the above setup, you will need to establish an acceptable trust path to the admin(s) of a monkeysphere-enabled server that you will be connecting to. You need to do this because the admin is certifying the host, and you need a mechanism to validate that certification. The only way to do that is by indicating who you trust to certify hosts. This is a two step process: first you must sign the key, and then you have to indicate a trust level. The process of signing another key is outside the scope of this document, however the gnupg README details the signing process and you can find good [documentation ](http://www.debian.org/events/keysigning) online detailing this process. If you have signed your admins' key, you need to denote some kind of trust to that key. To do this you should edit the key and use the 'trust' command. For the Monkeysphere to trust the assertions that are made about a host, you need full calculated validity to the host certifiers. This can be done either by giving full trust to one host-certifying key, or by giving marginal trust to three different host-certifiers. In the following we demonstrate how to add full trust validity to a host-certifying key: $ gpg --edit-key Command> trust pub 2048R/3B757F8C created: 2008-06-19 expires: 2008-11-16 usage: CA trust: unknown validity: full [ unknown ] (1). ssh://monkeysphere.info [ unknown ] (2) ssh://george.riseup.net Please decide how far you trust this user to correctly verify other users' keys (by looking at passports, checking fingerprints from different sources, etc.) 1 = I don't know or won't say 2 = I do NOT trust 3 = I trust marginally 4 = I trust fully 5 = I trust ultimately m = back to the main menu Your decision? 4 Note: Due to a limitation with gnupg, it is not currently possible to limit the domain scope properly, which means that if you fully trust an admin, this admin can currently assert host verification for any hosts. Because the Monkeysphre relies on GPG's definition of the OpenPGP web of trust, it is important to understand [how GPG calculates User ID validity for a key](/trust-models). Miscellaneous ------------- Users can also maintain their own `~/.ssh/authorized_keys` files with the Monkeysphere. This is primarily useful for accounts on hosts that are not already systematically using the Monkeysphere for user authentication. If you're not sure whether this is the case for your host, ask your system administrator. If you want to do this as a regular user, use the `update-authorized_keys` command: $ monkeysphere update-authorized_keys This command will take all the user IDs listed in the `~/.monkeysphere/authorized_user_ids` file and check to see if there are acceptable keys for those user IDs available. If so, they will be added to the `~/.ssh/authorized_keys` file. You must have indicated reasonable ownertrust in some key for this account, or no keys will be found with trusted certification paths. If you find this useful, you might want to place this command in your crontab so that revocations and rekeyings can take place automatically.