Update README.md

README.md

@@ -4,35 +4,69 @@
 ## Overview
 Brief description of what, why, how, and pointer to website.
 
-### What kind of events can falco detect?
+### What kind of events can Falco detect?
 
 
 
 ## Installing Falco
-Installation instructions.
+Instructions for installing via .deb, .rpm, or docker. To be filled in pre-release.
+
+For now, local compilation and installation is the way to install (see "Building Falco" below).
 
 ## Configuring Falco
 
-Digwatch is primarily configured via two files: a configuration file (such as the `falco.yaml` in this repository) and a rules file (such as the `digwatch_rules.conf` file in `rules/`). These two files are written to `/etc` after you install the Falco package.
+Digwatch is primarily configured via two files: a configuration file (such as the `falco.yaml` in this repository) and a rules file (such as the `falco_rules.conf` file in `rules/`). These two files are written to `/etc` after you install the Falco package.
 
 ### Rules file
-Explain the rules file syntax
+
+The rules file is where you define the events and actions that you want to be notified on. We've provided a sample rule file `./rules/falco_rules.conf` as a starting point, but you'll want to familiarize yourself with the contents, and most likely, to adapt it to your environment. 
+
+_Call for contributions: If you come up with additional rules which you think should be part of this core set - PR welcome! And likewise if you have an entirely separate ruleset that may not belong in the core rule set._
+
+A Falco rules file is comprised of two kinds of elements: rules and macro definitions. 
+
+Here's an example of a rule that alerts whenever a bash shell is run inside a container:
+
+`container.id != host and proc.name = bash | WARNING Bash run in a container (%user.name %proc.name %evt.dir %evt.type %evt.args %fd.name)`
+
+The part to the left of the pipe (`|`) is the _condition_. It is expressed using the Sysdig [filter syntax](http://www.sysdig.org/wiki/sysdig-user-guide/#filtering). Any Sysdig filter expression is a valid Falco expression (with the caveat of certain excluded system calls, discussed below). In addition, Falco expressions can contain _macro_ terms, which are not present in Sysdig syntax.
+
+The part to the right of the pipe is the _output_. It is composed of a priority level and an output format. The priority level is case-insensitive and should be one of "emergency", "alert", "critical", "error", "warning", "notice", "informational", or "debug". The output format specifies the message that should be output if a matching event occurs, and follows the Sysdig [output format syntax](http://www.sysdig.org/wiki/sysdig-user-guide/#output-formatting).
+
+Macro definitions provide a way to define common sub-portions of rules in a reusable way. The syntax for a macro is:
+
+`macro_name: macro_definition`
+
+where `macro_name` is a string, and `macro_definition` is any valid Falco condition. 
+
+(_insert example here_).
+
+
+
+
+
+
+
 
 ### Configuration file
-Explain the config file contents and syntax
+Falco is configured via a yaml file. The sample config `falco.yaml` in this repo has comments describing the various options.
-
 
 ## Running Falco
 
-Digwatch is intended to be run as a service. But for experimentation and designing/testing rulesets, you will likely want to run it manually from the command-line.
+Falco is intended to be run as a service. But for experimentation and designing/testing rulesets, you will likely want to run it manually from the command-line.
 
 ### Running Falco as a service
 Instructions for Centos and Ubuntu.
 
 ### Running Falco manually
 
+`falco --help`
+
+
 
 ## Building Falco
+Building Falco requires having `cmake` and `g++` installed.
+
 
 ### Building
 Clone this repo in a directory that also contains the sysdig source repo. The result should be something like:
@@ -60,15 +94,15 @@ $ make
 as a result, you should have a falco executable in `build/userspace/falco/falco`.
 
 
-### Running locally-built sysdig
+### Running locally-built Falco
 
-Assuming you are in the `build` dir, you can run falco as:
+Assuming you are in the `build` dir, you can run Falco as:
 
 `$ sudo ./userspace/falco/falco -c ../falco.yaml -r ../rules/falco_rules.conf`
 
 Or instead you can try using some of the simpler rules files in `rules`. Or to get started, try creating a file with this:
 
-Create a file with some [falco rules](Rule-syntax-and-design). For example:
+Create a file with some [Falco rules](Rule-syntax-and-design). For example:
 ```
 write: (syscall.type=write and fd.typechar=f) or syscall.type=mkdir or syscall.type=creat or syscall.type=rename
 interactive: proc.pname = bash or proc.pname = sshd