Unable to connect to SQL Database

Hello Team,

I am creating a sharepoint 2013 visual webpart wherein on button click I am connecting to a SQL database through ASP.net connection string written as :

"Initial Catalog=DBName;Data Source=IPAddress;User ID=UN;Password=PWD;Integrated Security=true"

When i open the connection using   con.Open();.It throws an error saying 

"Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'."

Can somebody please help !!

Thanks