Update updater.md

updater.md

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 # Updater
 
+The updater is the central piece to get your XOA on the latest bits of Xen Orchestra.
+
+It allows also to transform your current version in any others (Trial, Starter, Enterprise or Premium) **without downloading a new XOA**.
+
+## Requierements
+
+In order to work, the updater needs to access to xen-orchestra.com (port 443).
+
+## Usage
+
+The updater is configurable directly in the web interface, or via the CLI.
+
+### From the web interface
+
+By default for a new XOA, you'll have this icon in the top right:
+
+![](updater_notreg.png)
+
+It means your appliance is not registered. Click on this icon and follow the next step.
+
+#### Register
+
+Updates and trial will be available as soon as you registered your appliance. To register, use your https://xen-orchestra.com credentials you gave to download it previously (your email and your password):
+
+![](updater_reg.png)
+
+#### Upgrade
+
+#### Check for new versions
+
+### From the CLI
+
+If you interface is not accessible, or you just prefer to use CLIs commands, it's totally possible to do all the operations. You need to access your XOA by SSH.
+
+#### Register
+
+#### Upgrade
+
+#### Check for new versions
+
+## Troubleshooting
+
+Connect to your XOA in SSH then:
+
+* you should be able to successfully `ping xen-orchestra.com`
+* if not, check your `/etc/resolv.conf` file and modify it if necessary (give a correct DNS server)
+* use `ifconfig` to check your network configuration
+* check your firewall(s) and allow XOA to reach xen-orchestra.com (port 443)