add a few notes and a usage example

README.md

@@ -3,4 +3,52 @@
 Martin Schütte <info@mschuette.name>
 
 This module tries to automate the configuration of a Freifunk (Hamburg) Gateway.
+The idea is to implement the step-by-step guide on http://wiki.freifunk.net/Freifunk_Hamburg/Gateway
 
+A generalization for other communities would be nice, but right now this is all
+experimental and we will be glad when it works for our own gateways.
+
+Also note that this is a really ugly puppet module that ignores all principles
+of modularity and interoperability; instead it follows the "Big ball of mud"
+design pattern.
+
+## Usage
+
+Install as a puppet module, then include with node-specific parameters.
+
+Basically there are three kinds of parameters: user accounts (optional if you
+do manual user management), network config (has to be in sync with the wiki
+page), and credentials for fastd and openvpn.
+
+Example puppet code:
+
+```class { 'ff_gw':
+    # user accounts:
+    accounts => {
+        mschuett => {
+            comment => 'Martin Schuette',
+            ssh_key => 'AAAAB3NzaC1yc2EAAAADAQABAAABAQC4qcAOjmLCv+DaF405K9/napCQCq8qJnTJtkbeQR+PGLHAR3kxXFh5rQXKp5n3IxEhZt4js7yin5EBmfCMv+CHYSndT4BGVDarjqIoM7RAKI8MyJUus0SOf5WsnAGamp97mCh8iWHg7v+emqYcF308FFkubKzFLdHjdLGZBCduClUvkyuuUc7vtkXZ3IkInXGkrN5hn388/lHsT1ewUva7j2fZmbVou8P2FHC4+azPInoyezwiIE6YrFKAyquDhuFRDir5QqlFaZpD6C8T+vEiqWRyqPxI7YVGBudh2oec5m99VTWkrPw7cOsC92ndLAgQ2MjxEeDhPh/Tgxly6flb',
+            groups => ['sudo', 'users'],
+        }
+    },
+
+    # network config (example data for gw12)
+    mesh_mac        => 'de:ad:be:ef:01:14',
+    gw_ipv4         => '10.112.30.1',
+    gw_ipv6         => 'fd51:2bb2:fd0d::501',
+    dhcprange_start => '10.112.30.2',
+    dhcprange_end   => '10.112.31.254',
+
+    # secret credentials for fastd and vpn
+    secret_key      => '...',
+    vpn_ca_crt      => '-----BEGIN CERTIFICATE-----
+MIIE ...
+-----END CERTIFICATE-----',
+    vpn_usr_crt     => '-----BEGIN CERTIFICATE-----
+MIIE ...
+-----END CERTIFICATE-----',
+    vpn_usr_key     => '-----BEGIN CERTIFICATE-----
+MIIE ...
+-----END CERTIFICATE-----',
+}
+```