A slightly-modified version of Steve Kemp's Xen Shell is provided so that customers may perform some administrative tasks on their VPS, such as booting, shutting down and accessing its console even when it's not running or has no networking capability.
Accessing the Xen Shell
Access details are provided in /root/PASSWORDS when your VPS is provisioned. These credentials are common to all BitFolk customer interfaces (such as this wiki).
To connect to your Xen Shell, ssh to email@example.com, where username is the name of your BitFolk account. If you wish to authenticate by SSH key instead of your BitFolk password then you may manage the list of SSH keys from the BitFolk Panel.
BitFolk's sshds listen on port 22 and port 922 (see below).
If you've forgotten the password to your BitFolk account then you can do an email password reset using the "forgotten password" link on the login page of the Panel.
Being locked out
If you fail your login more than 10 times then your IP address will be firewalled off for 10 minutes from port 22. Port 922 is not subject to these lockouts.
SSH keys and "Too many authentication failures"
If you have many SSH keys in your agent then it might be presenting too many wrong ones first, and not giving you chance to log in. If you're experiencing this then you can work around it with IdentitiesOnly and specifying an identity file, as discussed in this SuperUser answer.
Using the Xen Shell
The Xen Shell is a character-based menu driven interface. It runs under GNU Screen so you can have multiple "windows" open at once, and if you disconnect then it will still be there when you connect again. This can be helpful if you want to issue Xen Shell commands in one window while watching your VPS's console in another.
The key bindings are as default for GNU Screen, so for example Ctrl+a then c will create a new window, Ctrl+a then a returns you to the previous window you were looking at, etc.
Using the console command will drop you into your VPS's console. This is similar to a serial console on a "real" server. In order to exit the console to get back to the main Xen Shell menu you need to type Ctrl+]. Alternatively you may find it more convenient to create a new window (Ctrl+a then c) which would start at the main menu. You could then toggle between console and menu with Ctrl+a then a.
The console will also allow you to use Magic SysRq keys using Ctrl+o. For example, the combination Ctrl+o then h will display the kernel's help for SysRq commands. SysRq commands can be useful in situations where your VPS crashes or becomes unresponsive even on the console: you might still be able to Sync, Unmount, and reBoot in these situations.
Will "destroy" damage my VPS?
destroy is roughly the equivalent of yanking the power on a "real" server; it isn't polite and has the potential for causing filesystem corruption, but it's unfortunately sometimes necessary with some types of problem. For example, if your VPS is in an OOM death spiral then it will be too busy swapping to be able to even shut down, so destroy would be your only recourse.
destroy is not intended to nuke your VPS or wipe your disks or anything. Suggestions for a less scary name for this command are appreciated.