My server is a CentOS updated server, running mod_security 2.5.9 (using EPEL yum
repo).

After installing this i've found that a call from a provider (i think is made
using a http call from .NET) don't pass anymore the paramters in the POST scope.

I've found that even including only modsecurity_crs_10_config.conf the problem
appears, so I've created a whitelist entry on the top of the file for source IP
but I want to understand what is the problem.

Could someone help me?

I've taken some examples using post_log apache module:
Without mod_security (i've marked some XXX for privacy)
==70370b74==============================
Request: 84.55.xx.xx 212.249.xx.xx - - [22/Dec/2009:19:05:42 +0100] "POST
/gateway/mobilex.cfm HTTP/1.1" 200 5313 "-" "NTH Gateway/5.43.1"
DejKlFQ3wEsAACZVMBAAAAAA "-"
Handler: jrun-handler
----------------------------------------
POST /gateway/mobilex.cfm HTTP/1.1
User-Agent: NTH Gateway/5.43.1
Connection: Close
Content-Type: application/x-www-form-urlencoded
Host: 84.55.xx.xx
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Content-Length: 142

142
destination=5555&messageid=6740368&keyword=FFF&sender=0041795244021&time=2009.12.22+19%3A06%3A04&text=fff+lungo+50+test&provider=22802&header=

HTTP/1.1 200 OK
Connection: close
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8

With mod_security:
==1c8fee30==============================
Request: 84.55.xx.xx 212.249.xx.xx - - [22/Dec/2009:18:56:42 +0100] "POST
/gateway/mobilex.cfm HTTP/1.1" 500 8467 "-" "NTH Gateway/5.43.1"
7bMmnFQ3wEsAACS@MF4AAAAB "-"
Handler: jrun-handler
----------------------------------------
POST /gateway/mobilex.cfm HTTP/1.1
User-Agent: NTH Gateway/5.43.1
Connection: Close
Content-Type: application/x-www-form-urlencoded
Host: 84.55.xx.xx
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Content-Length: 142

0


HTTP/1.1 500 The required parameter DESTINATION was not provided.
server-error: true
Content-Length: 8467
Connection: close
Content-Type: text/html; charset=UTF-8