X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=website%2Fgetting-started-admin.mdwn;h=aad4251740090a5fc025ef15fadb7bf79d2dcabe;hb=b959e0f646558328567c91b77d1ecee2c674099e;hp=e97c7944e0ea99af7cbba8bac2ed7229a9c2452d;hpb=8bba6f27dd299180bd55d9f27b8d1b219c356095;p=monkeysphere.git diff --git a/website/getting-started-admin.mdwn b/website/getting-started-admin.mdwn index e97c794..aad4251 100644 --- a/website/getting-started-admin.mdwn +++ b/website/getting-started-admin.mdwn @@ -1,77 +1,182 @@ Monkeysphere Server Administrator README ======================================== -FIXME: distinguish between publishing a new monkeysphere-enabled host -key and accepting user identification via the web-of-trust. + Note: This documentation is for Monkeysphere version 0.23 or later. + If you are running a version prior to 0.23, we recommend that you upgrade. +As the administrator of an SSH server, you can take advantage of the +Monkeysphere in two ways: -server service publication --------------------------- -To publish a server host key: +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 - # monkeysphere-server gen-key - # monkeysphere-server publish-key +2. you can set up your machine to automatically identify connecting +users by their presence in the OpenPGP Web of Trust. -This will generate the key for server with the service URI -(ssh://server.hostname). The server admin should now sign the server -key so that people in the admin's web of trust can authenticate the -server without manual host key checking: +These two pieces are independent: you can do one without the other. - $ gpg --search ='ssh://server.hostname' - $ gpg --sign-key ='ssh://server.hostname' +Monkeysphere for host verification (monkeysphere-host) +====================================================== +Server host key publication +--------------------------- -Update OpenSSH configuration files ----------------------------------- +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: -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 key): + # monkeysphere-host import-key /etc/ssh/ssh_host_rsa_key server.example.net - HostKey /var/lib/monkeysphere/ssh_host_rsa_key +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. -FIXME: should we just suggest symlinks in the filesystem here instead? +Now you can display information about the host key's certificate with +the 'show-key' command: -FIXME: What about DSA host keys? The SSH RFC seems to require that DSA be available, though OpenSSH will work without a DSA host key. + # monkeysphere-host show-key -To enable users to use the monkeysphere to authenticate against the -web-of-trust, add this line to /etc/ssh/sshd_config (again, making -sure that no other AuthorizedKeysFile directive exists): +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: - AuthorizedKeysFile /var/lib/monkeysphere/authorized_keys/%u + # monkeysphere-host publish-key +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. -MonkeySphere authorized_keys maintenance ----------------------------------------- +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: + + $ gpg --search '=ssh://server.example.net' + $ gpg --sign-key '=ssh://server.example.net' + +Make sure you compare the fingerprint of the retrieved certificate +with the output from the 'show-key' command above! + +Next, find out your key's Key ID, which is a hexadecimal string like "ABCDEF19" + + $ gpg --list-keys '=ssh://server.example.net' + +which will output something like: + + pub 2048R/ABCDEF19 2009-05-07 + uid [ full ] ssh://server.example.net + +Finally, publish your signatures back to the keyservers, so that your +users can automatically verify your machine when they connect: -A system can maintain monkeysphere authorized_keys files for it's -users. + $ gpg --send-key ABCDEF19 + +See http://web.monkeysphere.info/signing-host-keys/ for more info +signing host keys. + +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 +---------------------------------------- For each user account on the server, the userids of people authorized -to log into that account would be placed in: +to log into that account would be placed, one per line, in: + + ~/.monkeysphere/authorized_user_ids + +For example, this file could contain: - ~/.config/monkeysphere/authorized_user_ids + Joe User + Joe User at Work -However, in order for users to become authenticated, the server must -determine that the user 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 user. This would generally be -the server admin. If the server admin's keyid is XXXXXXXX, then on -the server run: +Provided that those exact strings are among the uids for which the user's gpg +key is valid. - # monkeysphere-server add-identity-certifier XXXXXXXX +The server will use the Monkeysphere to look up matching OpenPGP +certificates, validate them, and generate an `authorized_keys` file. -To update the monkeysphere authorized_keys file for user "bob", the -system would then run the following: +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. - # monkeysphere-server update-users bob +You will need to know your full 40 hex character gpg fingerprint. This can be learned by doing: -To update the monkeysphere authorized_keys file for all users on the + gpg --with-colons --fingerprint user@example.org + +Replacing "user@example.org" with either your gpg key id, or your gpg uid. +The output of this command is very long and difficult to read. Look for a line like: + + fpr:::::::::D8E6414012D371BFC5AB8E2540D6B49E0E708ADF: + +The portion between the ":::::::::" and ":" is your 40 digit fingerprint. + +With your OpenPGP 40-digit hex fingerprint replacing `$GPGFPR`, then +run the following command on the server: + + # monkeysphere-authentication add-identity-certifier $GPGFPR + +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. + +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-generated `authorized_keys` file for user +"bob", run: + + # monkeysphere-authentication update-users bob + +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 regularly. +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 + +Warning: Be aware that with this change in configuration, only those users whose +authorized keys files appear under the above path will be able to log in via +ssh. This includes the root user if root has ssh access. Remember to run +'monkeysphere-authentication update-users' if you are unsure whether any users' +authorized_keys files have been updated. -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.