The current implementation of the whitelist uses the name filed. Steam display names (what you see on your friends list) do not always match user names (the logon value associated to the Steam ID). Likewise, factorio has its own login name.
Is it possible to add the rejected name to the rejection string in the log files? Currently, the name is only displayed after they Successfully connect. However, it would be easier to add names to the whitelist if they appeared here.
Refusing connection for address(77.64.---.---:1062). UserNotWhitelisted
Update to something like:
Refusing connection for address(77.64.---.---:1062). UserNotWhitelisted [NameThatGoesInTheWhiteList]
[15.6] Whitelist Debug Request - UserNotWhitelisted
Re: [15.6] Whitelist Debug Request - UserNotWhitelisted
While not really a bug that does sound useful so I've added it for the next version of 0.15.
If you want to get ahold of me I'm almost always on Discord.