Monday, 30 September 2013

Get user's IP address in load balancing environment in ASP.NET

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One of our requirement is to get user's IP address in load balancing environment. Production servers are setup in load balancing environment (also known as Web Farm environment).
I've tried following Request Server Variables to get visitor's IP address
Response.Write("  HTTP_X_COMING_FROM" + Request.ServerVariables["HTTP_X_COMING_FROM"]);

Response.Write(" || HTTP_X_FORWARDED_FOR" + Request.ServerVariables["HTTP_X_FORWARDED_FOR"]);

Response.Write(" || HTTP_X_FORWARDED" + Request.ServerVariables["HTTP_X_FORWARDED"]);

Response.Write(" || HTTP_VIA" + Request.ServerVariables["HTTP_VIA"]);

Response.Write(" || HTTP_COMING_FROM" + Request.ServerVariables["HTTP_COMING_FROM"]);

Response.Write(" || HTTP_FORWARDED_FOR" + Request.ServerVariables["HTTP_FORWARDED_FOR"]);

Response.Write(" || HTTP_FORWARDED" + Request.ServerVariables["HTTP_FORWARDED"]);

Response.Write(" || HTTP_FROM " + Request.ServerVariables["HTTP_FROM"]);

Response.Write(" || HTTP_PROXY_CONNECTION" + Request.ServerVariables["HTTP_PROXY_CONNECTION"]);

Response.Write(" || CLIENT_IP" + Request.ServerVariables["CLIENT_IP"]);

Response.Write(" || FORWARDED " + Request.ServerVariables["FORWARDED"]);

Response.Write(" || REMOTE_ADDR " + Request.ServerVariables["REMOTE_ADDR"]);

Response.Write(" || HTTP_CLIENT_IP" + Request.ServerVariables["HTTP_CLIENT_IP"]);

Response.Write(" || X-Forwarded-For " + Request.ServerVariables["X-Forwarded-For"]);

Response.Write(" || X_FORWARDED_FOR " + Request.ServerVariables["X_FORWARDED_FOR"]);

Response.Write(" || REMOTE_HOST " + Request.ServerVariables["REMOTE_HOST"]);

Response.Write(" || HTTP_X_CLUSTER_CLIENT_IP " + Request.ServerVariables["HTTP_X_CLUSTER_CLIENT_IP"]);

Response.Write(" || User Host " + Request.UserHostAddress);
The main point to note is that load balancer is acting as a proxy. Based on Load Balancer setting HTTP_X_FORWARDED_FOR is returning visitor's IP address. REMOTE_HOST and REMOTE_ADDR are returning Load Balancer IP address.
By using HTTP_X_FORWARDED_FOR, I was able to get visitor's IP address but I got a small problem. Sometimes HTTP_X_FORWARDED_FOR is returning a comma delimited list of IP addresses!
For example:

HTTP_X_FORWARDED_FOR = "10.44.14.47, 82.132.237.233"
HTTP_X_FORWARDED_FOR = "10.16.36.14, 217.33.137.230, 95.131.110.106"
HTTP_X_FORWARDED_FOR = "192.168.10.47, 192.168.10.47, 127.0.0.1, 86.156.34.80"

Reason is that request has passed through multiple proxies thus HTTP_X_FORWARDED_FOR contains multiple IP address.

The general format of the field is:
X-Forwarded-For: client, proxy1, proxy2 

Use below code to get IP address :
HttpContext.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] ?? "").Split(',').Last().Trim();
The FIRST IP may be the real client behind many proxies, but it can be fake and easily be spoofed through headers using various tool and plugins like Firefox Tamper Data. So the correct way is to get the LAST IP from the list of IPs, which is the most reliable IP that connected to our servers. Check Wikipedia link for good read.
Using IP address to identify unique visitors is not reliable way.
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Sunday, 29 September 2013

Error -26204: Failed to execute SQL String during Sitecore Installation

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I was trying to install Sitecore CMS on computer and I got following error while installation :
Error 26204. Error -2147217900: failed to execute SQL string, error detail: Could not open File Control Bank (FCB) for invalid file ID 2 in database 'sitecoreSitecore_Core'. Verify the file location. Execute DBCC CHECKDB., SQL key: AttachSitecore_CoreSqlAuth SQL string: CREATE DATABASE [sitecoreSitecore_Core] ON ( FILENAME = N'E:\Inetpub\wwwroot\sitecore\Database\MDF\sitecoreSitecore.Core.MDF' ), ( FILENAME = N'E:\Inetpub\wwwroot\sitecore\Database\LDF\sitecoreSitecore.Core.ldf' ) FOR ATTACH
The Sitecore installation wizard kept failing at the Executing SQL Install Script step. Following steps resolved the issue:
  1. If you are using SQL Server, the user account configured to run the SQL server application requires Full access to the /Databases folder containing MDF and LDF database files. Typically, the SQL server application runs within the context of the NETWORK SERVICE account.
    In my case, database folder path was 'E:\Inetpub\wwwroot\sitecore\Database'. I've given EVERYONE and NETWORK SERVICE account full access on above path.
  2. Also, I've found that database folder path 'E:\Inetpub\wwwroot\sitecore\Database' was set as compressed to save disk space. I'd uncompressed 'E:\Inetpub\' folder. Below are the steps to set as uncompressed:
    • Right Click on Inetpub folder.
    • Click on Properties.
    • Click on Advanced.
    • Unchecked checkbox in front of Compress content to save disk space. See below screenshot for your reference:

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Saturday, 28 September 2013

Hello World !

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Hello World! I'm finally here.
This is the first publicly available piece of writing I've ever created. The pressure is on. I've actually put off writing this post for nearly three weeks now. It's not that I didn't want to post, but I felt that a first post needed to have some sort of special significance or insight. There are many things I plan to write about and hopefully they will live up to the name of this blog and prove insightful and helpful to people in many of various areas of technology. However, for my first post I want to start with an all encompassing post. Welcome to my blog.
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