This is a third party daemon which speaks SPOE. It gives requests send by HAProxy to ModSecurity and returns the verdict.
You must compile ModSecurity in standalone mode. Below an example for ModSecurity-2.9.1. Note that ModSecurity depends the Apache APR. I assume that the Apache dependencies are installed on the system.
./configure \ --prefix=$PWD/INSTALL \ --disable-apache2-module \ --enable-standalone-module \ --enable-pcre-study \ --without-lua \ --enable-pcre-jit make make -C standalone install mkdir -p $PWD/INSTALL/include cp standalone/.h $PWD/INSTALL/include cp apache2/.h $PWD/INSTALL/include
Note that this compilation method works, but is a little bit rustic. I can't deal with Lua, I supposed that is a dependencies problem on my computer.
After you have compiled it, to start the service, you just need to use "spoa" binary:
$> ./modsecurity -h
Usage: ./spoa [-h] [-d] [-p <port>] [-n <num-workers>] [-f <config-file>]
-h Print this message
-d Enable the debug mode
-f <config-file> Modsecurity configuration file
-m <max-frame-size> Specify the maximum frame size (default : 16384)
-p <port> Specify the port to listen on (default: 12345)
-n <num-workers> Specify the number of workers (default: 5)
-c <capability> Enable the support of the specified capability
-t <time> Set a delay to process a message (default: 0)
The value is specified in milliseconds by default,
but can be in any other unit if the number is suffixed
by a unit (us, ms, s)Note: A worker is a thread.
All information about SPOE configuration can be found in "doc/SPOE.txt". Here is the configuration template to use for your SPOE with ModSecurity module:
[modsecurity]
spoe-agent modsecurity-agent messages check-request option var-prefix modsec timeout hello 100ms timeout idle 30s timeout processing 15ms use-backend spoe-modsecurity
spoe-message check-request args unique-id method path query req.ver req.hdrs_bin req.body_size req.body event on-frontend-http-request
The engine is in the scope "modsecurity". So to enable it, you must set the following line in a frontend/listener section:
frontend my-front ... filter spoe engine modsecurity config spoe-modsecurity.conf ...
Because, in SPOE configuration file, we declare to use the backend "spoe-modsecurity" to communicate with the service, you must define it in HAProxy configuration. For example:
backend spoe-modsecurity mode tcp balance roundrobin timeout connect 5s timeout server 3m server modsec1 127.0.0.1:12345
The modsecurity action is returned in a variable called txn.modsec.code. It contains the HTTP returned code. If the variable contains 0, the request is clean.
http-request deny if { var(txn.modsec.code) -m int gt 0 }
With this rule, all the request not clean are rejected.
When the audit_log is used with the directive "SecAuditLogType Serial", in some systems, the APR mutex initialisation silently fails, this causes a segmentation fault. For my own usage, I have a patched version of modsec where I use another mutex than "APR_LOCK_DEFAULT" like "APR_LOCK_PROC_PTHREAD"
Configuration file loaded with wildcard (eg. Include rules/*.conf), are loaded in reverse alphabetical order. You can found a patch below. The ModSecurity team ignored this patch.
https://github.com/SpiderLabs/ModSecurity/issues/1285 http://www.arpalert.org/0001-Fix-bug-when-load-files.patch
Or insert includes without wildcards.