diff --git a/README.md b/README.md
index 275efd1..66f1526 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ Features:
 Docs:
 
 * docs/install.md -- generic installation instructions
+* docs/configuration.md -- config file description and configuration notes
 
 Similar software:
 
diff --git a/docs/configuration.md b/docs/configuration.md
new file mode 100644
index 0000000..7b7e99f
--- /dev/null
+++ b/docs/configuration.md
@@ -0,0 +1,102 @@
+General notes
+=============
+
+f2b config consists from main config `/etc/f2b/f2b.conf` and several config parts located in `/etc/f2b/conf-enabled/`.
+All config parts should ends with `.conf` and ill be sorted before processing.
+
+Config consists from several sections of various types:
+
+* [main] -- daemon settings
+* [defaults] -- jail defaults
+* [source:*] -- source module definitions
+* [filter:*] -- filter module definitions
+* [backend:*] -- backend module definitions
+* [jail:*] -- jail definitions
+
+Options may be redefined by creating section with same name and option with changed value. Like this:
+
+    # from f2b.conf
+    [main]
+    <skipped>
+    loglevel = info  # <- you want to redefine this
+    # from conf-enabled/99-local.conf
+    [main]
+    loglevel = error # <- this will be actual value
+
+Also you need to define one or more jails.
+Each jail should have at least `source`, `filter` and `backend` options.
+Missing options will be inherited from `[default]` section.
+Jail will be ignored unless `enabled` option set to `yes`.
+
+Example:
+
+    [jail:test] # <- this jail will be named 'test'
+    enabled = yes
+    source = files:/var/log/messages
+    # search for source named `files` and init it with string '/var/log/messages'
+    filter = preg:/etc/f2b/filters/ssh.preg
+    # search for filter named 'preg' and init it with path '/etc/f2b/filters/ssh.preg'
+    # note '.preg' extension - it's a hint for you,
+    # that this file contains regexps compatible with posix syntax
+    # see regex(7) manpage
+    backend = exec-ipset:banned
+    # search for backend named 'exec-ipset' and init it with string 'banned'
+    # So <ID> token will be replaced with 'banned' string
+
+Module-specific settings
+========================
+
+Each module has so-called "init string" with different syntax for each module.
+Example:
+
+    [jail:test]
+    <skipped>
+    backend = backend_name:init-string
+
+Source-modules
+--------------
+
+files
+:   Init string is path to file which should be polled for data.
+    Also may by file pattern if `glob = yes` is set.
+    For pattern syntax see glob(7)
+
+redis
+:   Init string is name of pubsub channel on redis server (will be prefixed with "f2b-")
+    Options are:
+    * server -- ip address for redis server we should connect
+    * port -- redis server port (set if non-standart)
+    * database -- database number on redis server (see SELECT redis command)
+    * password -- password for redis auth after connect (see AUTH redis command)
+
+Filter-modules
+--------------
+
+Init string is path to file with patterns list. Each pattern should has exactly one <HOST> token in place of ip address appears.
+
+preg
+:   Only option is `icase` - set to 'yes' for case-insensitive pattern matches
+    This module has additional restriction. <HOST> token must be placed before first capture group.
+
+pcre
+:   Options are:
+    * icase -- set to 'yes' for case-insensitive pattern matches
+    * study -- if set to 'yes' each pattern consumes more memory, but matches faster
+    * usejit -- set to 'yes' to use jit pcre usage (only for pcre >= 8.20)
+
+Backend-modules
+---------------
+
+Each backend has at least these options:
+* shared  -- is this module may be reused between different jails
+* timeout -- timeout for commands ban/check/unban
+
+exec
+:   Init string is arbitrary string which may be used in args of executed command(s) with <ID> token.
+    Options start/stop/ban/unban/check should contain path to script/binary to execute on named action.
+    This options can be used more than once, commands will be executed in order they appers in config.
+    Tokens <ID>/<IP> will be replaced with actual values.
+
+redis
+:   Init string is name of pubsub channel on redis server (will be prefixed with "f2b-")
+    Options almost the same as source/redis. 'ping' option - for keeping connection alive (see PING redis command)