The beep when users connect plays a system beep on every connection.  This option only works when CrushFTP is running in GUI mode.

Always do transfers in binary prevents CrushFTP from altering ascii text files line endings even if the FTP client request such.

The hide splash screen will keep CrushFTP from displaying its startup window.

The check for new versions allows CrushFTP to notify you when a new version has been found.  A new version can either be downloaded from the check for update from the file menu or by going directly to my website.

Allow MacBinary operations is a global enable/disable for MacBinary support.  Sometimes you just don't want it to be possible.

Allow extended PASV/PORT as EPSV/EPRT is a compatibility thing.  Some clients just can't handle if its enabled because of a network configuration.

Allow directory caching determines if Crush will keep temporary caches of dir listings to reduce the CPU load on CrushFTP with very active servers.

Use 'ls -la' for dir listings will use the native OS command to get a dir listing for FTP so that Crush can report the true owner, group, and privs information.

Auto IP discovery is how often CrushFTP should scan to be sure your current external IP is still the same.
If you want to specify your external IP address, you do so in the box in the [IP Servers] window.

CrushFTP can announce itself via Bonjour (formerly Rendevouz) so clients that are Bonjour aware you just select CrushFTP from the drop down list.  No need to know IP addresses.

Slow down hack attempts will incrementally slow down responses to clients that appear to be a robot scanning for writable directories on your server.  This makes their scan take a lot longer, and helps make those robots less useful.  It doesn't use any extra CPU load.

Disable referer cookie will disable crush forwarding a user who was deep linking into a specific directory after they have authenticated.

The default privs option lets you specify the default privs to be applied to new folders as you add them to users in the user manager.  It can save you a couple clicks to enter the data here.  If your unsure of what to put, open a users VFS.XML file to see an example of the permissions. (read)(write)(view)(delete)(resume)(rename)(makedir)(deletedir)

The date and time format is a Java format for how to log time stamps with each line.  If you want to alter it, check out the formatting character by googling : java simpledateformat.

The default owner and group of settings files allows CrushFTP to change the owner and group of all settings files as it is writing them.  So if you don't want the settings files all owned by root for some reason, you change these settings here.

CrushFTP is keeping backups every time you make a change and save a user in the User Manager.  If for some reason you don't want so many kept, you can control the setting here.  Additionally, if you have an alternate localization you want to use, or a custom one with different messages, you can specify it here.

Localizations are XML files that are in the Localization folder.  On OS X, this is in CrushFTP4.app/Contents/Resources/Java/Localization/.  Never edit the current.xml file as your changes will be lost immediately.  Instead, duplicate the "English.XML" file to some other name and make your changes their.  Then specify the name of your localization here without the ".XML".  It may take two restarts in a row of CrushFTP for your changes to take full affect.  CrushFTP copies over the current localization file and replaces the current.xml file.  If you do a partial, or full translation of CrushFTP into another language, please send me the XML file so that I may include it in my official releases.

ZIP Compression level is what CrushFTP will use when zipping files/folders on the fly.  Did you know you can ask for any folder name plus add on ".zip" and crush will instead zip it and send it to you?

The reverse of this zip on the fly is .zipstream.  Any file that is named with the extension .zipstream will be unzipped as its coming in, never writing the zip file to disk.  This allows for seamless decompression on the fly with all protocols.

Another unique feature is ':filetree'.  Downloading this special file in any directory will instead give you a text file of all files and subdirectories from that current location.

Disable MDTM modifications allows you to block FTP clients that upload a file, then set the modified date on the file.

Delete partial uploads will remove any files that don't make it to what appears not to be a complete successful upload.

Remote admin refresh interval will specify how frequently to have the remote admin window update.  Having this be too fast may make a very busy server have trouble.

Disable dir filtering allows you to disable FTP clients that look for files by asking the server to filter down its list based on a filter string.

Delay between dir listings allows you to make a client pause before they can get another dir listing.  Some clients may recursively list your entire FTP server repeatedly looking for changes making you use a lot of server CPU to do fulfill their requests.  Here you can slow them down.

Allow re-use in email events allows you to have multiple email events that all include the same notifications on files.  Rarely would you want this.

Remember invalid usernames will make crush block a robot testing for passwords.  Some robots will scan your server very heavily using a lot of CPU while crush tries to verify on your LDAP server, or whatever if the user is valid.  This option will block the username attempted for so many seconds after one failed login attempt before it bothers to even try again.  If the username is valid in the CrushFTP [user manager] it will ignore this setting and allow them to keep trying new passwords.

Run events asynchronously allows you to have events "complete" even when say an email server is slow to process the outgoing message or a LaunchProcess event is slow to finish.

The server welcome message is how CrushFTP identifies itself to clients when they connect.

The WebDAV timezone offset lets you manually adjust times reported to WebDAV to fix some clients being off by so many hours.