========================================
As the administrator of an SSH server, you can take advantage of the
-monkeysphere in two ways: you can publish the host key of your machine
-so that your users can have it automatically verified, and you can set
-up your machine to automatically identify connecting users by their
-presence in the OpenPGP web of trust.
+Monkeysphere in two ways:
+1. you can publish the host key of your machine to the Web of Trust
+(WoT) so that your users can automatically verify it, and
+
+2. you can set up your machine to automatically identify connecting
+users by their presence in the OpenPGP Web of Trust.
+
+These two pieces are independent: you can do one without the other.
+
+Monkeysphere for host verification (monkeysphere-host)
+======================================================
Server host key publication
---------------------------
-To generate and publish a server host key:
- # monkeysphere-server gen-key
- # monkeysphere-server publish-key
+To begin, you must first import an ssh host key. This assumes that
+you have the ssh server installed, and that you have generated a host
+RSA key. Once that has been done, import the key:
-This will generate the key for server with the service URI
-(`ssh://server.example.net`). The server admin should now sign the
-server key so that people in the admin's web of trust can identify the
-server without manual host key checking:
+ # monkeysphere-host import-key /etc/ssh/ssh_host_rsa_key server.example.net
- $ gpg --search '=ssh://server.example.net'
- $ gpg --sign-key '=ssh://server.example.net'
+This will generate an OpenPGP certificate for the server. The primary
+user ID for this certificate will be the ssh service URI for the host,
+(eg. `ssh://server.example.net`). Remember that the name you provide
+here should probably be a fully qualified domain name for the host in
+order for your users to find it.
+Now you can display information about the host key's certificate with
+the 'show-key' command:
-Update OpenSSH configuration files
-----------------------------------
+ # monkeysphere-host show-key
-To use the newly-generated host key for ssh connections, put the
-following line in `/etc/ssh/sshd_config` (be sure to remove references
-to any other keys):
+Once the host key's certificate has been generated, you'll probably
+want to publish it to the public keyservers which distribute the Web
+of Trust:
- HostKey /var/lib/monkeysphere/ssh_host_rsa_key
+ # monkeysphere-host publish-key
-FIXME: should we just suggest symlinks in the filesystem here instead?
+But anyone could publish a simple self-signed certificate to the WoT
+with any name attached. Your users should be able to tell that
+someone they know and trust with the machine (e.g. *you*, the
+administrator) has verified that this particular key is indeed the
+correct key. So your next step is to sign the host's key with your
+own OpenPGP key.
-FIXME: What about DSA host keys? The SSH RFC seems to require implementations support DSA, though OpenSSH will work without a DSA host key.
+On your (the admin's) local machine retrieve the host key (it may take
+several minutes for the key to propagate across the keyserver
+network), and sign it:
-To enable users to use the monkeysphere to authenticate using the
-OpenPGP web of trust, add this line to `/etc/ssh/sshd_config` (again,
-making sure that no other AuthorizedKeysFile directive exists):
+ $ gpg --search '=ssh://server.example.net'
+ $ gpg --sign-key '=ssh://server.example.net'
- AuthorizedKeysFile /var/lib/monkeysphere/authorized_keys/%u
+Make sure you compare the fingerprint of the retrieved certificate
+with the output from the 'show-key' command above!
+
+Finally, publish your signatures back to the keyservers, so that your
+users can automatically verify your machine when they connect:
+
+ $ gpg --send-key '=ssh://server.example.net'
+
+See http://web.monkeysphere.info/signing-host-keys/ for more info
+signing host keys.
-And then read the section below about how to ensure these files are
-maintained. You'll need to restart `sshd` to have your changes take
-effect. As with any change to `sshd_config`, be sure to retain an
-existing session to the machine while you test your changes so you
-don't get locked out.
+Monkeysphere for user authentication (monkeysphere-authentication)
+==================================================================
+A host can maintain ssh-style `authorized_keys` files automatically
+for its users with the Monkeysphere. This frees you (the
+administrator) from the task of manually checking/placing SSH keys,
+and enables users to do relatively painless key transitions, and to
+quickly and universally revoke access if they find that their ssh key
+has become compromised.
+
+You simply tell the system what *person* (identified by her OpenPGP
+User ID) should have access to an account, the Monkeysphere takes care
+of generating the proper `authorized_keys` file and keeping it
+up-to-date, and `sshd` reads the generated `authorized_keys` files
+directly.
Monkeysphere authorized_keys maintenance
----------------------------------------
-A host can maintain ssh authorized_keys files automatically for its
-users with the Monkeysphere.
-
For each user account on the server, the userids of people authorized
to log into that account would be placed in:
~/.monkeysphere/authorized_user_ids
-However, in order for users to become authenticated, the server must
-determine that the user IDs on their keys have "full" validity. This
-means that the server must fully trust at least one person whose
-signature on the connecting user's key would validate the relevant
-user ID. The individuals trusted to identify users like this are
-known in the Monkeysphere as "Identity Certifiers". In a simple
-scenario, the host's administrator would be trusted identity certifer.
-If the admin's OpenPGP keyid is `$GPGID`, then on the server run:
+The server will use the Monkeysphere to look up matching OpenPGP
+certificates, validate them, and generate an `authorized_keys` file.
+
+To validate the OpenPGP certificates, the server needs to know who it
+can trust to correctly identify users. The individuals trusted to
+identify users like this are known in the Monkeysphere as "Identity
+Certifiers". One obvious choice is to trust *you*, the administrator,
+to be an Identity Certifier. If your OpenPGP keyid is `$GPGID`, then
+run the following command on the server:
+
+ # monkeysphere-authentication add-identity-certifier $GPGID
+
+You'll probably only set up Identity Certifiers when you set up the
+machine. After that, you'll only need to add or remove Identity
+Certifiers when the roster of admins on the machine changes, or when
+one of the admins switches OpenPGP keys.
- # monkeysphere-server add-identity-certifier $GPGID
+Now that the server knows who to trust to identify users, the
+Monkeysphere can generate ssh-style `authorized_keys` quickly and
+easily:
-To update the monkeysphere authorized_keys file for user "bob" using
-the current set of identity certifiers, run:
+To update the Monkeysphere-generated `authorized_keys` file for user
+"bob", run:
- # monkeysphere-server update-users bob
+ # monkeysphere-authentication update-users bob
-To update the monkeysphere authorized_keys file for all users on the
+To update the monkeysphere `authorized_keys` file for all users on the
the system, run the same command with no arguments:
- # monkeysphere-server update-users
+ # monkeysphere-authentication update-users
You probably want to set up a regularly scheduled job (e.g. with cron)
-to take care of this automatically.
+to do this automatically.
+
+Update OpenSSH server AuthorizedKeysFile configuration
+------------------------------------------------------
+
+Generating the `authorized_keys` files is not quite enough, because
+`sshd` needs to know where to find the generated keys.
+
+You can do this by adding the following line to
+`/etc/ssh/sshd_config`, commenting out any other `AuthorizedKeysFile`
+directives:
+
+ AuthorizedKeysFile /var/lib/monkeysphere/authorized_keys/%u
-FIXME: document other likely problems and troubleshooting techniques
+You'll need to restart `sshd` to have your changes take effect. As
+with any change to `sshd_config`, if you're doing this remotely, be
+sure to retain an existing session to the machine while you test your
+changes so you don't get locked out if something went wrong.
projects / monkeysphere.git / blobdiff