The following is a collection of howtos that cover most of the common questions asked about ProFTPD and how to configure it.

Recommended order of reading:

On how to compile ProFTPD
Covers the various options to the configure script used by ProFTPD's build system
The proftpd.conf file
Covers the location and format of ProFTPD's configuration file, and some of the basic functionality
On configuring the ServerType
Covers how to configure ProFTPD to operate as a standalone daemon or one run via inetd/xinetd
On how clients are authenticated
Covers the steps taken in authenticating a user, and how authentication involves PAM, chroots, shells, etc.
On DefaultRoot and chroots
Covers the DefaultRoot configuration directive, chroots, and why symlinks do not work as expected when chroots are in effect
On AuthUserFiles
Covers the use of AuthUserFile and AuthGroupFile
On the Umask directive
Covers how Umask works, including a basic introduction to Unix filesystem permissions
On debugging
Covers how to configure the daemon so that it produces debugging output, which greatly helps in diagnosing problems
On ProFTPD release versioning
Covers the version naming convention used for ProFTPD releases
On <VirtualHost> sections
Covers how to configure virtual servers, listening on only one IP address, and how the daemon handles client connections to its virtual servers
On virtual users
Covers what virtual users are, how proftpd can be configured to handle virtual users from various sources (i.e. SQL, flat files, LDAP, etc).
On <Directory> sections
Covers how <Directory> sections should be configured, and how the configured paths are matched
On IPv6 support
Covers how IPv6 support and limitations
On .ftpaccess files
Covers how .ftpaccess files work
On <Limit> sections
Covers how <Limit> sections should be configured, and how different <Limit>s interact
On using proftpd in a firewall/NAT environment
Covers how NAT and passive FTP data transfers work, how to configure proftpd to operate in such environments
On ProFTPD quotas
Covers how the mod_quotatab module can be used for implementing quotas
On ProFTPD and timestamps
Covers the situation where the timestamps which appear in log files and directory listings may change, or not be what you expect
On the ListOptions directive
Covers how the ListOptions directive can be used to specify the directory listing options for clients, including showing hidden files and disabling recursive directory listings
On upgrading
Covers the best way to perform an upgrade of ProFTPD
On DSO modules
Covers what DSO modules are, and how to use them properly
On connection ACLs
Covers implementing connection ACLs, and some of the performance concerns related to the different mechanisms
On ASCII transfers
Covers ASCII mode for data transfers, and the affected FTP commands
On FXP, also known as site-to-site transfers
Covers why allowing site-to-site transfers is considered a bad idea, and how to configure proftpd to allow them
On DNS usage
Covers when and how proftpd uses the DNS
On sendfile support
Describes what the sendfile(2) function does, and some cases where it should not be used
On the FTP commands supported
Provides descriptions of the FTP commands supported by the daemon, including some common SITE commands
On the various forms of logging
Covers the various log files that ProFTPD can generate, and how logging capabilities can be extended
On the specific log levels supported
Covers the various log levels that ProFTPD uses for its log messages
On SQL configurations
Covers configuring mod_sql and how to set up your SQL tables, and some of the common questions about using mod_sql
On RADIUS configurations
Covers configuring mod_radius
On memcache support
Covers configuring and using memcache by various modules
On Redis support
Covers configuring and using Redis by various modules
On TCP/FTP/SSH keepalive functionality
Covers keeping long-lived connections alive, using TCP, FTP, and SSH specific mechanisms
On using FTP over SSH
Covers tunneling FTP over SSH
On SSL/TLS configurations
Covers configuring the daemon to handle FTP over SSL/TLS (also known as FTPS), including some of the common questions about FTPS.
On starting/stopping the daemon
Covers how the daemon is commonly started, stopped, and restarted, and includes an example init script
On the ScoreboardFile
Covers what the scoreboard does, and some of the common questions about scoreboards
On Classes
Covers defining and using classes
On Display files
Covers the various Display directives
On the CreateHome directive
Covers how to configure the daemon to create home directories on-demand
On Controls
Covers Controls and mod_ctrls
On rewriting commands using mod_rewrite
Contains a collection of examples of mod_rewrite configurations that solve a variety of different problems
On Tracing
Covers trace logging
On Filters
Covers the various Filter directives, and how to write regular expressions that match what you want
On configuration tricks
Covers various ways that can be used to make the proftpd.conf work in conditional ways
On Regular Expressions
Covers POSIX regular expressions
On ProFTPD and AWS
Covers deploying/using proftpd within AWS
On running proftpd as a nonroot user
Covers configuring proftpd to run as a nonroot user
On globbing
Covers what globbing is, how it can cause problems, and how to configure the daemon to defend against globbing attacks
On testing of proftpd
Covers functional, integration, and regression tests of proftpd, and how to run the testsuite
On translations of proftpd into other languages
Covers which parts of proftpd are translated, and how to add new translations
On best common practices
Covers some of the best common and recommended practices for configuring and running proftpd
On ProFTPD's ECCN
Covers the ECCN classification of the ProFTPD Project software

If your question or issue is not covered by any of these pages, please send a request to the ProFTPD documentation list. Directions for subscribing to the docs list, as well as the other ProFTPD mailing lists, are at:

  http://www.proftpd.org/lists.html

  http://www.proftpd.org/docs/directives/index.html