Setting up access control is an important initial step as the system initially is wide open.

When Tvheadend verifies access is scan through all the enabled access control entries. The permission flags are combined for all matching access entries. An access entry is said to match if the username / password matches and the IP source address of the requesting peer is within the prefix.

The access rules are listed / edited in a grid.

The columns have the following functions:

Enabled
Make the entry participate in access control. If disabled, the entry is inactive.
Username
Name of user, if no username is needed for match it should contain a single asterisk (*).
Password
Password to combine with user, if username is '*' (unused), the password should be the same.
Prefix
IPv4 prefix for matching based on source IP address. If set to 0.0.0.0/0 it will match everything.
Streaming
Enables access to streaming function. The 'streaming' access is enough to make Showtime (over HTSP) work.
Video Recorder
Enables access to all video recording functions. This also include administration of the auto recordings.
All Configs (VR)
Allow use of and configuration of DVR configuration profiles.
Web interface
Required for web user interface access. Also gives access to the EPG.
Admin
Enables access to the Configuration tab.
Channel Tag Only
If enabled, the user will only be able to access channels with a tag the same name as the username. This provides a very rudimentary way of limiting access to certain channels.
Comment
Allows the administrator to set a comment only visible in this editor. It does not serve any active purpose.

Let's also take a look at an example:

First line gives clients originating from 192.168.0.0 - 192.168.0.255 network access to streaming functions. Typically you would use this for your local media players at home (All though Showtime can prompt for username & password in its HTSP client)

The second line adds a user with world wide access who might want to modify recordings, etc, perhaps from the job, or mobile phone.

The third line provide admin access to the 'admin' user. As an extra precaution this user is only allowed to log in from the home network.