mod_client_management: Use grant id from key This is a minor tweak - it's faster and preserves compatibility with older data formats (that we don't necessarily want to be compatible with, but some of us have messy data stores and it pays to be a little more robust).

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
modules_enabled = {
    -- other modules --
    "s2s_whitelist",

}
s2s_whitelist = {
    "example.org",
}
```