IIS Log Request Body / POST Data

Question

Does anyone know how I could get IIS to log POST data or the entire HTTP request?

Answer 1

The IIS logs only record querystring and header information without any POST data.

If you're using IIS7, you can enabled Failed Request Tracing for status code 200. That will record all of the data and you can select which type of data to include.

In either IIS6 or 7, you can use Application_BeginRequest in global.asax and create your own logging of POST data.

Or, in IIS7, you can write a HTTP Module with your own custom logging.

Answer 2

In managed code you can use the Response.AppendToLog method.  This method will append data to the cs-uri-stem field -- the total length is up to 4100 characters (undocumented).  If you exceed that limit, then the value that would have been logged is replaced with "..."

For instance, adding something like this to your Global.asax file should do the trick (C#):

void Application_EndRequest(Object Sender, EventArgs e)
{
    if( "POST" == Request.HttpMethod )
    {
        byte[] bytes    = Request.BinaryRead(Request.TotalBytes);
        string s    = Encoding.UTF8.GetString(bytes);
        if (!String.IsNullOrEmpty(s))
        {
            int QueryStringLength = 0;
            if (0 < Request.QueryString.Count)
            {
                QueryStringLength = Request.ServerVariables["QUERY_STRING"].Length;
                Response.AppendToLog( "&" );
            }

            if (4100 > ( QueryStringLength + s.Length ) )
            {
                Response.AppendToLog(s);
            }
            else
            {
                // append only the first 4090 the limit is a total of 4100 char.
                Response.AppendToLog(s.Substring(0, ( 4090 - QueryStringLength )));
                // indicate buffer exceeded
                Response.AppendToLog("|||...|||");
                // TODO: if s.Length >; 4000 then log to separate file
            }
        }       
    }
}
 

Answer 3

While I appreciate that this is an old question, I found this code gave me exactly what I needed, a text file with the complete request headers and the response, put it into your global.asax.cs:

protected void Application_BeginRequest(Object Sender, EventArgs e)
{
    string uniqueid = DateTime.Now.Ticks.ToString();
    string logfile = String.Format("C:\\path\\to\\folder\\requests\\{0}.txt", uniqueid);
    Request.SaveAs(logfile, true);
}

This will create a text file for each and every request (including images) so be careful where you use it. I only used it to log specific post requests.

Answer 4

Try this in your web.config file to trace everything

<tracing>
  <traceFailedRequests>
    <remove path="*" />
    <add path="*">
      <traceAreas>
        <add provider="ASP" verbosity="Verbose" />
        <add provider="ASPNET" areas="Infrastructure,Module,Page,AppServices" verbosity="Verbose" />
        <add provider="ISAPI Extension" verbosity="Verbose" />
        <add provider="WWW Server" areas="Authentication,Security,Filter,StaticFile,CGI,Compression,Cache,RequestNotifications,Module,FastCGI,WebSocket,Rewrite" verbosity="Verbose" />
      </traceAreas>
      <failureDefinitions timeTaken="00:00:00" statusCodes="200-999" />
    </add>
  </traceFailedRequests>
</tracing>

Answer 5

This looks encouraging, though I have not yet tried it:

https://www.codeproject.com/Tips/1213108/HttpModule-for-Logging-HTTP-POST-Data-in-IIS-Log

How does this differ from the other option offered here, with code in the global.asax.cs? That would only work for ASP.NET page requests, not other pages IIS might process (php, cgi, jsp, cfml). The link I shared is to a module that one could enable in IIS for any site (or at the server level) to process for any type of request.

Answer 6

Try enabling the following in your IIS log settings:

Method (cs-method)

URI Stem (cs-uri-stem)

URI Query (cs-uri-query)